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The knowledge about co-transport of goethite and As 3+ to investigate the effect of goethite colloids on As 3+ transport under various degrees of seawater intrusion, particular extremely conditions, in groundwater environment is still limited. The main objective is to investigate the influence of seawater intrusion on the sorption, migration, and reaction of As 3+ and goethite colloids into sand aquifer media under anoxic conditions by using the bench-scale and reactive geochemical modeling. The research consisted of two parts as follows: 1) column transport experiments consisting of 8 columns, which were packed by using synthesis groundwater at IS of 0.5, 50, 200, and 400 mM referring to the saline of seawater system in the study area, and 2) reactive transport modeling, the mathematical model (HYDRUS-1D) was applied to describe the co-transport of As 3+ and goethite. Finally, to explain the interaction of goethite and As 3+ , the Derjaguin-Landau-Verwey-Overbeek (DLVO) calculation was considered to support the experimental results and HYDRUS-1D model. The results of column experiments showed goethite colloids can significantly inhibit the mobility of As 3+ under high IS conditions (>200 mM). The R f of As 3+ bound to goethite grows to higher sizes (47.5 and 65.0 μm for 200 and 400 mM, respectively) of goethite colloid, inhibiting As 3+ migration through the sand columns. In contrast, based on R f value, goethite colloids transport As 3+ more rapidly than a solution with a lower IS (0.5 and 50 mM). The knowledge gained from this study would help to better understand the mechanisms of As 3+ contamination in urbanized coastal groundwater aquifers and to assess the transport of As 3+ in groundwater, which is useful for groundwater management, including the optimum pumping rate and long-term monitoring of groundwater quality., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Goethite often harbors impurities, such as phosphorus (P) and aluminum (Al), which are incorporated into its structure through direct substitution or coprecipitation with nanocrystalline phases. Understanding the processes that drive the release of P and Al from goethite is of paramount importance for the iron ore industry and for managing nutrient and pollutant behavior in the environment. This study investigates the impact of Fe(II)-catalyzed recrystallization on the release of P and Al from goethite. We evaluated the solubility and extractability of P and Al in suspensions of Al- and P-coprecipitated goethite, treated with 57 Fe-enriched Fe(II) aq under oxygen-free conditions for 30 days at neutral pH and room temperatures. The addition of Fe(II) aq induced the recrystallization of goethite dominant initial synthetic phases (i.e., low P- and Al-containing phases) and the transformation of higher P- and/or Al-bearing starting material that was actually a mixture of goethite and minor amounts of lepidocrocite and feroxyhyte. Our results reveal that Fe(II)-catalyzed mineral and structural evolution led to the repartitioning of P and, to a lesser extent, Al throughout the crystal structure, mineral surface, and aqueous solution. Following a 30 day reaction with Fe(II) aq , we extracted approximately 80, 68.8, 73.9, and 83.2% of P from P-only, low, medium, and high P + Al goethite, respectively. Additionally, we observed total Al removals of approximately 17, 27, and 25% from low, medium, and high P + Al goethite, respectively. The results demonstrate that treating both P-only and P + Al goethite with Fe(II) at room temperature, followed by a 24 h extraction using 1 M NaOH, significantly enhances the overall extractability of P and Al, including both aqueous and surface-adsorbed fractions, compared to Fe(II)-free controls. These findings advance our understanding of the recrystallization process and impurity substitution in goethite, offering promising avenues for developing new environmentally friendly methods to extract P and other impurities from goethitic iron ores at lower temperatures.

This study exposes U(VI)-sorbed schwertmannite and jarosite to biotic reductive incubations under field-relevant conditions and examines the changes in aqueous and solid-phase speciation of U, Fe, and S as well as associated microbial communities over 180 days. The chemical, X-ray absorption spectroscopy, X-ray diffraction, and microscopic data demonstrated that the U(VI)-sorbed schwertmannite underwent a rapid reductive dissolution and solid-phase transformation to goethite, during which the surface-sorbed U(VI) was partly reduced and mostly repartitioned to monomeric U(VI)/U(IV) complexes by carboxyl and phosphoryl ligands on biomass or organic substances. Furthermore, the microbial data suggest that these processes were likely driven by the consecutive developments of fermentative and sulfate- and iron- reducing microbial communities. In contrast, the U(VI)-sorbed jarosite only stimulated the growth of some fermentative communities and underwent very limited reductive dissolution and thus, remaining in its initial state with no detectable mineralogical transformation and solid-phase U reduction/repartitioning. Accordingly, these two biotic incubations did not induce increased risk of U reliberation to the aqueous phase. These findings have important implications for understanding the interactions of schwertmannite/jarosite with microbial communities and colinked behavior and fate of U following the establishment of reducing conditions in various acidic and U-rich settings.

Estimating the availability of phosphorus in soils and sediments is complicated by the diverse mineralogical properties of iron (hydr)oxides that control the environmental fate of phosphorus. Despite various surface complexation models have been developed, lack of generic phosphate affinity constants (logK PO4 s) for iron (hydr)oxides hinders the prediction of phosphate adsorption to iron (hydr)oxides in nature. The aim of this work is to derive generic logK PO4 s for the Charge Distribution-Multisite Complexation extended-Stern-Gouy-Chapman (CD-MUSIC-eSGC) model using a large phosphate adsorption database and previously derived generic protonation parameters. The optimized logK PO4 s of goethite, hematite and ferrihydrite are located in a much narrower range than those in the RES 3 T database. Specifically, the logK PO4 ranges of FeOPO 3 , FeOPO 2 OH, FeOPO(OH) 2 , (FeO) 2 PO 2 , and (FeO) 2 POOH complexes were 17.40-18.00, 24.20-27.40, 27.90-29.80, 26.50-29.60, and 30.70-33.40, respectively. A simplified CD-MUSIC-eSGC model with species FeOPO 2 OH and (FeO) 2 PO 2 and generic logK PO4 values 26.0 ± 0.9 and 27.9 ± 0.8, respectively, provides an accurate prediction of phosphate adsorption and dominant speciation to the iron (hydr)oxides at environmental pH and phosphate levels. For ferrihydrite at low pH and high phosphate levels the species FeOPO(OH) 2 and (FeO) 2 POOH cannot be neglected. The simplified model expands the application boundaries of CD-MUSIC-eSGC model in predicting the phosphate adsorption on natural iron (hydr)oxides without laborious characterization., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

To control acid mine drainage (AMD) from the source, a new environmentally and green passivator (biochar) has been introduced to passivate pyrite. To reduce the difficulty of biochar preparation and cost, and improve its production scale, in-situ pyrolysis of applewood by smoldering to produce biochar. Here, particle size, moisture content and gas flow rate were selected to prepare biochar by smoldering through orthogonal combination, and the pyrite was passivated with different conditions and biochar concentrations (2 g/L, 3 g/L, 4 g/L). The results revealed that when the particle size is 200 mm×200 mm×20 mm, the water content is 20-30%, and the gas flow rate is 0.4 L/m 3 , the biochar yield is the highest. Biochar promotes the formation of passivating layer (jarosite), inhibits the release of metal ions. Increasing biochar concentration can promote the formation of jarosite and enhance the passivation effect on pyrite., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Ocean alkalinity enhancement is considered as an effective atmospheric CO 2 removal approach, but currently, little is known about the carbon sequestration potential of implementing olivine addition in offshore waters. We investigated the effect of olivine addition on the seawater carbonate system by carrying out a deck incubation experiment in the Northern Yellow Sea; the dissolution rate of olivine was calculated based on the increase in seawater alkalinity (TA), and the CO 2 sequestration potential was evaluated. The results showed that the dissolution of olivine increased seawater TA and decreased partial pressure of CO 2 , resulting in oceanic CO 2 uptake from the atmosphere through sea-air exchange; it also increased seawater pH and mitigated ocean acidification to a certain extent. The addition of 1 ‰ olivine had a more significant effect on the seawater carbonate system than 0.5 ‰ olivine addition. The average dissolution rate constant of olivine was 1.44 ± 0.15 μmol m -2  d -1 . Assuming that olivine settles completely on the seabed due to gravity, the theoretically maximum amount of CO 2 removed by applying 1 tonne of olivine per square meter area in the Northern Yellow Sea is only 2.0 × 10 -4  t/m 2 . Therefore, when olivine addition is implemented in the offshore waters, it is necessary to consider reducing the olivine size, prolonging the settling time of olivine in the water column; and spreading olivine in well-mixed waters to prolong the residence time through repeated resuspension, thus increasing its potential in carbon sequestration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The interaction between organic phosphorus (OP) and iron oxide significantly influences the phosphorus cycle in the natural environment. In shallow lakes, intense oxidation-reduction fluctuations constantly alter the existing form of iron oxides, but little is known about their impact on the adsorption and fractionation of OP molecules. In this study, electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS) was used to investigate the fractionation of OP from alkali-extracted sediment induced by crystalline goethite and amorphous ferrihydrite adsorption at a molecular scale. The results showed that ferrihydrite and goethite both exhibited high OP adsorption, and the adsorption amount decreased as the pH increased. The adsorption kinetics matched the pseudo-second-order equation. The ESI-FT-ICR MS analysis showed that 91 P-containing formulas were detected in the alkaline-extracted sediment solution. Ferrihydrite and goethite adsorbed 51 and 24 P-containing formulas, respectively, with adsorption rates of 56.0 % and 26.4 %. Ferrihydrite could adsorb more OP compounds than goethite, but no obvious molecular species selectivity was observed during the adsorption. The P-containing compounds, including unsaturated hydrocarbons-, lignin/carboxyl-rich alicyclic molecule (CRAM)-, tannin-, and carbohydrate-like molecular compounds, were more suitable for iron oxide adsorption. The double bond equivalence (DBE) is a valuable parameter that indicates OP fractionation during adsorption, and P-containing compounds with lower DBE values such as lipid- and protein-like molecular were prone to remain in the solution after adsorption. These research results provide insights into the biogeochemical cycling process of P in the natural environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Serious arsenic (As) contaminations could commonly result from the oxidative dissolution of As-containing sulfide minerals, such as arsenopyrite (FeAsS). Pyrite (Py) and calcite (Cal) are two typically co-existing reactive minerals and represent different geological scenarios. Previous studies have shown that a high proportion of Py can generate a stronger galvanic effect and acid dissolution, thereby significantly promoting the release of arsenic. However, this conclusion overlooks calcite's antagonistic effect on the release of As in the natural environment. That antagonistic effect could remodel the linear relationship of pyrite on the oxidative dissolution of arsenopyrite, thus altering the environmental risk of As. We examined As release from arsenopyrite along a gradient of Py to Cal molar ratios (Py:Cal). The results showed that the lowest As release from arsenopyrite was surprisingly found in co-existing Py and Cal systems than in the singular Cal system, let alone in the singular Py system. This phenomenon indicated an interesting possibility of Py assistance to Cal inhibition of As release, though Py has always been regarded as a booster, also evidenced in this research, for As release from arsenopyrite. In singular systems of Py and Cal, As continued to be released for 60 days. However, in co-existing Py and Cal systems, As was released non-linearly in three stages over time: initial release (0-1 Day), immobilization (1-15 Days), and subsequent re-release (>15 Days). This is a new short-term natural attenuation stage for As, but over time, this stage gradually collapses. During the re-release stage (> 15 Days), a higher molar ratio of Py:Cal (increasing from 1:9 to 9:1) results in a lower rate constant k (mg·L -1 ·h -1 ) of As release (range from 0.0011 to 0.0002), and a higher abundance of secondary minerals formed (up to 26 mg/g goethite and hematite at Py: Cal=9:1). This demonstrates that increasing the Py:Cal molar ratio results in the formation of more secondary minerals which compensate for the higher potential antagonistic mechanisms generated by pyrites, such as acid dissolution and galvanic effect. These results explain the mechanisms of the high-risk characteristics of As both in acidic mine drainage and karst aquifers and discover the lowest risk in pyrite and calcite co-existing regions. Moreover, we emphasize that reactive minerals are important variables that can't be ignored in predicting As pollution in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Schwertmannite (Sch) holds a great promise as an iron material for remediating Arsenic (As)-contaminated paddy soils, due to its extremely high immobilization capacities for both arsenate [As(V)] and arsenite [As(III)]. However, there is still limited knowledge on the mineral phase transformation of this metastable iron-oxyhydroxysulfate mineral in paddy soils, particularly under different water management regimes including aerobic, intermittent flooding, and continuous flooding, and how its phase transformation impacts the migration of As in paddy soils. In this study, a membrane coated with schwertmannite was first developed to directly reflect the phase transformation of bulk schwertmannite applied to paddy soils. A soil incubation experiment was then conducted to investigate the mineral phase transformation of schwertmannite in paddy soils under different water management regimes and its impact on the migration of As in paddy soil. Our findings revealed that schwertmannite can persist in the paddy soil for 90 days in the aerobic group, whereas in the continuous flooding and intermittent flooding groups, schwertmannite transformed into goethite, with the degree or rate of mineral phase transformation being 5% Sch >1% Sch > control. These results indicated that water management practices and the amount of schwertmannite applied were the primary factors determining the occurrence and degree of mineral transformation of schwertmannite in paddy soil. Moreover, despite undergoing phase transformation, schwertmannite still significantly reduced the porewater As (As(III) and As(V)), and facilitated the transfer of non-specifically adsorbed As (F1) and specifically adsorbed As (F2) to amorphous iron oxide-bound As (F3), effectively reducing the bioavailability of soil As. These findings contribute to a better understanding of the mineralogical transformation of schwertmannite in paddy soils and the impact of mineral phase transformation on the retention of As in soil, which carry important implications for the application of schwertmannite in remediating As-contaminated paddy soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Fate and transport of nanoplastics in aquatic environments are affected by their heteroaggregation with minerals in the presence of macromolecules. This study investigated the heteroaggregation of polystyrene nanoplastics (PSNPs) with goethite nanoparticles (GNPs) under the influence of macromolecules [humic acid (HA), bovine serum albumin (BSA), and DNA] and electrolytes. Under 1 mg C/L macromolecule, raising electrolyte concentration promoted heteroaggregation via charge screening, except that calcium bridging with HA also enhanced heteroaggregation at CaCl 2 concentration above 5 mM. At all NaCl concentrations and CaCl 2 concentration below 5 mM, 1 mg C/L macromolecules strongly retarded heteroaggregation, ranking BSA > DNA > HA. Raising macromolecule concentration strengthened such stabilization effect of all macromolecules in NaCl solution and that of DNA and BSA in CaCl 2 solution by enhancing steric hindrance. However, 0.1 mg C/L BSA slightly promoted heteroaggregation in CaCl 2 solution due to stronger electrostatic attraction than steric hindrance. In CaCl 2 solution, raising HA concentration strengthened its destabilization effect via calcium bridging. Macromolecules having more compact globular structure and higher molecular weight may exert greater steric hindrance to inhibit heteroaggregation more effectively. This study provides new insights on the effects of macromolecules and electrolytes on heteroaggregation between nanoplastics and iron minerals in aquatic environments., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Iron (Fe) and manganese (Mn) oxides can be used to remediate Cd-polluted soils due to their excellent performance in heavy metal adsorption. However, their remediation capability is rather limited, and a higher content of available Mn and Fe in soils can reduce Cd accumulation in wheat plants due to the competitive absorption effect. In this study, goethite and cryptomelane were first respectively used to immobilize Cd in Cd-polluted weakly alkaline soils, and sodium citrate was then added to increase the content of available Mn and Fe content for further reduction of wheat Cd absorption. In the first season, the content of soil-available Cd and Cd in wheat plants significantly decreased when cryptomelane, goethite and their mixture were used as the remediation agents. Cryptomelane showed a better remediation effect, which could be attributed to its higher adsorption performance. The grain Cd content could be decreased from 0.35 mg kg -1 to 0.25 mg kg -1 when the content of cryptomelane was controlled at 0.5%. In the second season, when sodium citrate at 20 mmol kg -1 was further added to the soils with 0.5% cryptomelane treatment in the first season, the content of soil available Cd was increased by 14.8%, and the available Mn content was increased by 19.5%, leading to a lower Cd content in wheat grains (0.16 mg kg -1 ) probably due to the competitive absorption. This work provides a new strategy for the remediation of slightly Cd-polluted arable soils with safe and high-quality production of wheat., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Biochar-derived dissolved organic matter (BDOM), is extensively involved in the recrystallization of minerals and the speciation alteration of associated toxic metals. This study investigates how BDOM extracted from tobacco petiole (TP) or tobacco stalk (TS) biochar influences the speciation repartitioning of Cr(VI) in environments impacted by acid mine drainage (AMD), focusing on interactions with secondary minerals during Schwertmannite (Sch) dissolution and recrystallization. TP-BDOM, rich in lignin-like substances, slowed down the Cr-Sch dissolution and Cr release under acidic conditions compared to TS-BDOM. TP-BDOM's higher O/C component exerts a delayed impact on Cr-Sch stability and Cr(VI) reduction. In-situ ATR-FTIR and 2D-COS analysis showed that carboxylic and aromatic N-OH groups in BDOM could interact with Cr-Sch surfaces, affecting sulfate and Cr(VI) release. It was also observed that slight recrystallization occurred from Cr-Sch to goethite, along with increased Cr incorporation into secondary minerals within TS-BDOM. This enhances our understanding of BDOM's role in Cr(VI) speciation changes in AMD-contaminated sites., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Sorption of Pu(VI) onto synthesized goethite under oxidizing and normal conditions was investigated, which revealed its pH dependence on different solid/liquid ratios. Pu speciation upon sorption on the solid phase was characterized via extended X-ray absorption fine structure (EXAFS) spectroscopy, while that in solution was assessed using ultraviolet-visible (UV-Vis) spectroscopy and liquid-liquid extraction. The obtained results demonstrate differences in plutonium behavior in the studied systems. Pu(VI) remains hexavalent on the goethite surface and in solution under oxidizing conditions. While Pu(IV) is stabilized on the mineral and Pu(V) is found in solution under normal conditions. This study provides the thermodynamic descriptions of these reactions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The adsorption of heavy metals on iron oxides generally increases with pH and is almost complete at neutral to slightly alkaline pH. However, almost complete adsorption on a linear scale does not imply sufficient removal of the heavy metals in terms of their toxicity. Here, we elucidated the chemical reactions that determine the solid-liquid partitioning of Pb(II) and Cd(II) on goethite at high pH. While the removal of both heavy metals was almost complete on a linear scale above pH 7 for Pb(II) and pH 9 for Cd(II), the dissolved metal concentrations decreased on a logarithmic scale with pH, reaching minima at around pH 10 for Pb(II) and pH 10-11 for Cd(II), and then they increased with pH thereafter. The XAFS spectra of Pb(II)- or Cd(II)-adsorbed goethite prepared at pH > 11 were almost the same as those at neutral pH, suggesting that removal of the heavy metals from solution was achieved by a single adsorption reaction over the entire pH range. Based on the observed macroscopic and microscopic adsorption behaviors at high pH, a robust surface complexation model was developed to predict the solid-liquid partitioning of divalent heavy metals over the entire pH range., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Manganese oxides reduce arsenic (As) toxicity by promoting aqueous-phase As(III) oxidation and immobilization in natural aquatic ecosystems. In anaerobic water-sediment systems, arsenic exists both in a free state in the liquid phase and in an adsorbed state on iron (Fe) minerals. However, the influence of different manganese oxides on the fate of As in this system remains unclear. Therefore, in this study, we constructed an anaerobic microbial As(V) reduction environment and investigated the effects of three different manganese oxides on the fate of both aqueous-phase and goethite-adsorbed As under different pH conditions. The results showed that δ-MnO 2 had a superior As(III) oxidation ability in both aqueous and solid phase due not only to the higher SSA, but also to its wrinkled crystalline morphology, less favorable structure for bacterial reduction, structure conducive to ion exchange, and less interference caused by the formation of secondary Fe-minerals compared to α-MnO 2 and γ-MnO 2 . Regarding aqueous-phase As, δ-MnO 2 , α-MnO 2 , and γ-MnO 2 required an alkaline condition (pH 9) to exhibit their strongest As(III) oxidation and immobilization capability. For goethite-adsorbed As, under microbial-reducing conditions, all manganese oxides had the highest As immobilization effect in neutral pH environments and the strongest As oxidation effect in alkaline environments. This was because at pH 7, Fe(II) and Mn(II) formed hydrated complexes, which was more favorable for As adsorption. At pH 9, the negatively charged state of goethite hindered As adsorption but promoted the adsorption and oxidation of As by the manganese oxides. Our research offers new insights for optimizing As removal from water using various manganese oxides and for controlling the mobilization of As in water-sediment system under different pH conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

The abiotic oxidation of As(III) is simultaneously mediated by the oxidation of Fe(II) in microaerobic environment, but the role of Fe minerals in the Fe(II)-mediated As(III) oxidation have been neglected. This work mimicked the microaerobic environment and examined the mechanisms of Fe(II) mediated the As(III) oxidation in the presence of Fe minerals using a variety of iron minerals (lepidocrocite, goethite, etc.). The results indicated the Fe(II) and As(III) oxidation rate were improved with Fe minerals, while As(III) oxidation efficiency increased by 1.3-1.8 times in comparison to that without minerals. Fe(II) mediated the As(III) oxidation happened on Fe minerals surface in the presence of Fe minerals. The As(III) oxidation efficiency increased with increasing Fe mineral concentrations (from 0.5 to 2 g L -1 ) but decreased with increasing pH values. Reactive oxygen species (ROS) that play a crucial role in As(III) oxidation were Fe(IV) and ·O 2 - , accounting for 42.7%-47.9% and 24.1%-29.8%, respectively. The Fe minerals facilitated the oxidation of As(III) by ROS and stimulated the release of ROS through the adsorbed-Fe(II) oxidation, both of which favored As(III) oxidation. This work highlighted the potential mechanisms of Fe minerals in promoting Fe(II) mediated the As(III) oxidation in microaerobic environment, especially in terms of As(III) oxidation efficiency, shedding a valuable insight on optimization of arsenic contaminated wastewater treatment processes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Arsenic (As) pollution in water poses a significant threat to the ecological environment and human health. Meanwhile, the resource utilisation of coal gangue is of utmost importance in ecologically sustainable development. Thus, the FeOOH@coal gangue composite (FeOOH@CG) was synthesised for As(V) adsorption in this study. The results showed that α-FeOOH, β-FeOOH and Schwertmannite loaded on the surface of FeOOH@CG. Moreover, the adsorption behaviour of As(V) by FeOOH@CG was investigated under different reaction conditions, such as pH, contact time, initial concentration and co-existing anions. The optimum adsorption conditions were as follows: initial As(V) concentration of 60 mg/L, pH of 3.0 and adsorption time of 180-240 h. The adsorption capacity of FeOOH@CG for As(V) was pH-dependent and the maximum adsorption capacity was 185.94 mg/g. The presence of anions ( H 2 PO 4 - , HCO 3 - and C l - ) decreased the adsorption efficiency of FeOOH@CG for As(V). The adsorption process of FeOOH@CG for As(V) could be well-described by the pseudo-second-order model and Langmuir model, indicating that the adsorption process mainly depended on chemical adsorption. The thermodynamic analysis suggested that the adsorption was a spontaneous and endothermic process. In addition, according to the analyses of XRD, FTIR and XPS, the dominant mechanisms of As(V) adsorption by FeOOH@CG were electrostatic attraction, complexation and precipitation. In conclusion, FeOOH@CG has great potential as an efficient and environmentally friendly adsorbent for As(V) adsorption from aqueous solution.

The intricate organization of goethite nanorods within a silica-rich matrix makes limpet teeth the strongest known natural material. However, the mineralization pathway of goethite in organisms under ambient conditions remains elusive. Here, by investigating the multi-level structure of limpet teeth at different growth stages, it is revealed that the growth of goethite crystals proceeds by the attachment of amorphous nanoparticles, a nonclassical crystallization pathway widely observed during the formation of calcium-based biominerals. Importantly, these nanoparticles contain a high amount of silica, which is gradually expelled during the growth of goethite. Moreover, in mature teeth of limpet, the content of silica correlates with the size of goethite crystals, where smaller goethite crystals are densely packed in the leading part with higher content of silica. Correspondingly, the leading part exhibits higher hardness and elastic modulus. Thus, this study not only reveals the nonclassical crystallization pathway of goethite nanorods in limpet teeth, but also highlights the critical roles of silica in controlling the hierarchical structure and the mechanical properties of limpet teeth, thus providing inspirations for fabricating biomimetic materials with excellent properties., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The high efficiency, economy, sustainability and no secondary pollution of U(VI) removal is an important and challenging topic for U(VI) wastewater treatment. Here, the regenerable biohybrids with xanthan gum (XG) stabilized biogenic mackinawite nanoparticles (BX-FeS) were prepared, where XG acted as carrier facilitated the Fe 2+ attachment and induced the low size, high stability and activity of nearly spherical FeS nanoparticles. Results showed that BX-FeS kept high activity after storing two years and good performance for U(VI) removal in broad pH range and co-existence of ions, and had greater removal efficiency (97.9 %) than biogenic B-FeS (67.1 %). Moreover, BX-FeS preformed high adsorption capacity in uranium wastewater (658.0 mg/g), and lower cost compared with zerovalent-iron and silica gel. Importantly, BX-FeS maintained high activity within three regeneration cycles driven by Desulfovibrio desulfuricans, inhibited the secondary pollution (Fe 3+ , SO 4 2- ) of reaction. This study provides a new strategy for sustainable and efficient treatment of U(VI) wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this study, an efficient stabilizer material for cadmium (Cd 2+ ) treatment was successfully prepared by simply co-milling olivine with magnesite. Several analytical methods including XRD, TEM, SEM and FTIR, combined with theoretical calculations (DFT), were used to investigate mechanochemical interfacial reaction between two minerals, and the reaction mechanism of Cd removal, with ion exchange between Cd 2+ and Mg 2+ as the main pathway. A fixation capacity of Cd 2+ as high as 270.61 mg/g, much higher than that of the pristine minerals and even the individual/physical mixture of milled olivine and magnesite, has been obtained at optimized conditions, with a neutral pH value of the solution after treatment to allow its direct discharge. The as-proposed Mg-based stabilizer with various advantages such as cost benefits, green feature etc., will boosts the utilization efficiency of natural minerals over the elaborately prepared adsorbents., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

This work developed a method using bamboo shoot shells as raw material to produce Fe-modified ACs combining self-activation and chemical modification. Adding small amounts (0.5-5 %) of K 2 FeO 4 accelerated the pyrolysis process and CO 2 release, and reduced the activation energy and temperature of self-activation reaction. This increased the reaction rate and activation efficiency, ultimately significantly improving the pore structure of ACs. The addition of 3 % K 2 FeO 4 resulted in a substantial increase in specific surface area and pore volume of AC, from 1340 m 2 /g and 0.72 cm 3 /g to 2184 m 2 /g and 1.34 cm 3 /g, respectively. Additionally, the introduction of K 2 FeO 4 also enabled iron doping on the surface of the ACs. The improvement of pore structure and iron doping further enhanced the adsorption performance of ACs. The adsorption capacities of ACs for arsenate, ibuprofen, and tetracycline were up to 1.64, 1.50, and 2.38 times higher, respectively, than those of ACs prepared through conventional self-activation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The radiohybrid (rh) concept to design targeted (and chemically identical) radiotracers for imaging or radionuclide therapy of tumors has gained momentum. For this strategy, a new bifunctional Silicon-based Fluoride Acceptor (SiFA) moiety (SiFA)SeFe was synthesized, endowed with improved hydrophilicity and high versatility of integration into rh-compounds. Preliminary radiolabeling and stability studies under different conditions were conducted using model bioconjugate peptides. Further, three somatostatin receptor 2 (sstR2)-targeted rh-compounds ( (SiFA)SeFe-rhTATE1-3 , TATE = (Tyr 3 )-octreotate) were developed. Compound (SiFA)SeFe-rhTATE3 , enables labeling with 18 F for PET imaging or chelation of 177 Lu for therapy. The rh-compounds possess comparable receptor binding affinity and in vitro performance as good as the clinically proven gold standards. SstR2-specificity was further shown for (SiFA)SeFe-rhTATE2 using the chicken chorioallantoic membrane (CAM) model. The biodistribution of two compounds in mice showed high accumulation in tumors and excretion via the kidneys, demonstrating the clinical applicability of the (SiFA)SeFe moiety.

The surface photochemical activity of goethite, which occurs widely in surface soils and sediments, plays a crucial role in the environmental transformation of various pollutants and natural organic matter. This study systemically investigated the mechanism of different types of surface hydroxyl groups on goethite in generating reactive oxygen species (ROSs) and Fe(III) reduction under sunlight irradiation. Surface hydroxyl groups were found to induce photoreductive dissolution of Fe(III) at the goethite-water interface to produce Fe 2+ (aq) , while promoting the production of ROSs. Substitution of the surface hydroxyl groups on goethite by fluoride significantly inhibited the photochemical activity of goethite, demonstrating their important role in photochemical activation of goethite. The results showed that the surface hydroxyl groups (especially the terminating hydroxyl groups, ≡FeOH) led to the formation of Fe(III)-hydroxyl complexes via ligand-metal charge transfer on the goethite surface upon photoexcitation, facilitating the production of Fe 2+ (aq) and •OH. The bridging hydroxyl groups (≡Fe 2 OH) were shown to mainly catalyze the production of H 2 O 2 , leading to the subsequent light-driven Fenton reaction to produce •OH. These findings provide important insights into the activation of molecular oxygen on the goethite surface driven by sunlight in the environment, and the corresponding degradation of anthropogenic and natural organic compounds caused by the generated ROSs.

Perfluorooctanesulfonate (PFOS), a toxic anionic perfluorinated surfactant, exhibits variable electrostatic adsorption mechanisms on charge-regulated minerals depending on solution hydrochemistry. This work explores the interplay of multicomponent interactions and surface charge effects on PFOS adsorption to goethite surfaces under flow-through conditions. We conducted a series of column experiments in saturated goethite-coated porous media subjected to dynamic hydrochemical conditions triggered by step changes in the electrolyte concentration of the injected solutions. Measurements of pH and PFOS breakthrough curves at the outlet allowed tracking the propagation of multicomponent reactive fronts. We performed process-based reactive transport simulations incorporating a mechanistic network of surface complexation reactions to quantitatively interpret the geochemical processes. The experimental and modeling outcomes reveal that the coupled spatio-temporal evolution of pH and electrolyte fronts, driven by the electrostatic properties of the mineral, exerts a key control on PFOS mobility by determining its adsorption and speciation reactions on goethite surfaces. These results illuminate the important influence of multicomponent transport processes and surface charge effects on PFOS mobility, emphasizing the need for mechanistic adsorption models in reactive transport simulations of ionizable PFAS compounds to determine their environmental fate and to perform accurate risk assessment.

Microbially mediated Fe(II) oxidation has a great potential for attenuating arsenic (As) mobility in an anoxic groundwaters. Green rust (GR), a common Fe(II)-bearing phase in such environments, could be easily oxidized into Fe (oxyhydr)oxides through microbial activity. This study focused on Acidovorax sp. strain BoFeN1, an anaerobic nitrate-reducing Fe(II)-oxidizing (NRFO) bacterium, to promote the transformation of GR. In biotic GR transformation experiments, magnetite formation occurred at [As] ini  = 5 mg/L while lepidocrocite and goethite were formed at [As] ini  = 10 mg/L. In the absence of bacterium, the GR persisted throughout the 120-h experiment. Meanwhile, with the addition of strain BoFeN1, the final aqueous As concentration significantly decreased from 0.237 to 0.004 mg/L (C 0  = 5 mg/L) and from 1.457 to 0.096 mg/L (C 0  = 10 mg/L) at 120 h. It was indicated that strain BoFeN1 played a crucial role in promoting the GR transformation and enhancing As immobilization. Further investigations revealed that the role of strain BoFeN1 extended beyond Fe-oxidation. With nitrite (the intermediate of nitrate bioreduction) as oxidizer, lepidocrocite/goethite were formed in the chemical-oxidation system, excluding magnetite. In the Bio - [As] ini  = 5 mg/L, the occurrence of lepidocrocite via the bio-oxidation of Fe(II) in GR at 24 h, along with the metabolism of strain BoFeN1 reducing nitrate accompanied with H + consumption, it should be reasonably deduced that the alkaline micro-environment of periplasm induced by strain BoFeN1 were vital for the transformation of lepidocrocite to magnetite triggered by trace Fe(II). However, in the Bio - [As] ini  = 10 mg/L, more As adsorbed on GR inhibiting the adsorption of bacterium, so the alkaline micro-environment had no obvious effect on such transformation. This study helps to understand the interdependence between GR and anaerobic NRFO bacterium, and provides a new perspective for more effective As remediation strategies in anoxic groundwaters., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In urbanized areas, extracellular DNA (exDNA) is suspected of carrying genes with undesirable traits like virulence genes (VGs) or antibiotic resistance genes (ARGs), which can spread through horizontal gene transfer (HGT). Hence, it is crucial to develop novel approaches for the mitigation of exDNA in the environment. Our research explores the role of goethite, a common iron mineral with high adsorption capabilities, in exDNA adsorption processes. We compare well-crystalline, semi-crystalline, and nano goethites with varying particle sizes to achieve various specific surface areas (SSAs) (18.7-161.6 m 2 /g) and porosities. We conducted batch adsorption experiments using DNA molecules of varying chain lengths (DNA sizes: <11 Kb, <6 Kb, and <3 Kb) and assessed the impact of Ca 2+ and biomacromolecules on the adsorption efficacy and mechanisms. Results show that porosity and pore structure significantly influence DNA adsorption capacity. Goethite with well-developed meso- and macroporosity demonstrated enhanced DNA adsorption. The accumulation of DNA on the goethite interface led to substantial aggregation in the system, thus the formation of DNA-goethite conjugates, indicating the bridging between mineral particles. DNA chain length, the presence of Ca 2+ , and the biomacromolecule matrix also affected the adsorption capacity and mechanism. Interactions between DNA and positively charged biomacromolecules or Ca 2+ led to DNA compaction, allowing greater DNA accumulation in pores. However, a high concentration of biomacromolecules led to the saturation of the goethite surface, inhibiting DNA adsorption. AFM imaging of goethite particles after adsorption suggested the formation of the DNA multilayer. The study advances understanding of the environmental behavior of exDNA and its interaction with iron oxyhydroxides, offering insights into developing more effective methods for ARGs removal in wastewater treatment plants. By manipulating the textural properties of goethite, it's possible to enhance exDNA removal, potentially reducing the spread of biocontamination in urban and industrial environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Investigating the fate of persistent organic pollutants in water distribution systems (WDSs) is of great significance for preventing human health risks. The role of iron corrosion scales in the migration and transformation of organics in such systems remains unclear. Herein, we determined that hydroxyl ( • OH), chlorine, and chlorine oxide radicals are generated by Fenton-like reactions due to the coexistence of oxygen vacancy-related Fe(II) on goethite (a major constituent of iron corrosion scales) and hypochlorous acid (HClO, the main reactive chlorine species of residual chlorine at pH ∼ 7.0). • OH contributed mostly to the decomposition of atrazine (ATZ, model compound) more than other radicals, producing a series of relatively low-toxicity small molecular intermediates. A simplified kinetic model consisting of mass transfer of ATZ and HClO, • OH generation, and ATZ oxidation by • OH on the goethite surface was developed to simulate iron corrosion scale-triggered residual chlorine oxidation of organic compounds in a WDS. The model was validated by comparing the fitting results to the experimental data. Moreover, the model was comprehensively applicable to cases in which various inorganic ions (Ca 2+ , Na + , HCO 3 - , and SO 4 2- ) and natural organic matter were present. With further optimization, the model may be employed to predict the migration and accumulation of persistent organic pollutants under real environmental conditions in the WDSs.

Despite extensive study, geochemical modeling often fails to accurately predict lead (Pb) immobilization in environmental samples. This study employs the Charge Distribution MUlti-SIte Complexation (CD-MUSIC) model, X-ray absorption fine structure (XAFS), and density functional theory (DFT) to investigate mechanisms of phosphate (PO 4 ) induced Pb immobilization on metal (hydr)oxides. The results reveal that PO 4 mainly enhances bidentate-adsorbed Pb on goethite via electrostatic synergy at low PO 4 concentrations. At relatively low pH (below 5.5) and elevated PO 4 concentrations, the formation of the monodentate-O-sharing Pb-PO 4 ternary structure on goethite becomes important. Precipitation of hydropyromorphite (Pb 5 (PO 4 ) 3 OH) occurs at high pH and high concentrations of Pb and PO 4 , with an optimized log K sp value of -82.02. The adjustment of log K sp compared to that in the bulk solution allows for quantification of the overall Pb-PO 4 precipitation enhanced by goethite. The CD-MUSIC model parameters for both the bidentate Pb complex and the monodentate-O-sharing Pb-PO 4 ternary complex were optimized. The modeling results and parameters are further validated and specified with XAFS analysis and DFT calculations. This study provides quantitative molecular-level insights into the contributions of electrostatic enhancement, ternary complexation, and precipitation to phosphate-induced Pb immobilization on oxides, which will be helpful in resolving controversies regarding Pb distribution in environmental samples.

Iron (hydr)oxides are abundant in surface environment, and actively participate in the transformation of organic pollutants due to their large specific surface areas and redox activity. This work investigated the transformation of tetracycline (TC) in the presence of three common iron (hydr)oxides, hematite (Hem), goethite (Goe), and ferrihydrite (Fh), under simulated sunlight irradiation. These iron (hydr)oxides exhibited photoactivity and facilitated the transformation of TC with the initial phototransformation rates decreasing in the order of: Hem > Fh > Goe. The linear correlation between TC removal efficiency and the yield of HO• suggests that HO• dominated TC transformation. The HO• was produced by UV-induced decomposition of self-generated H 2 O 2 and surface Fe 2+ -triggered photo-Fenton reaction. The experimental results indicate that the generation of HO• was controlled by H 2 O 2 , while surface Fe 2+ was in excess. Sunlight-driven H 2 O 2 production in the presence of the highly crystalline Hem and Goe occurred through a one-step two-electron reduction pathway, while the process was contributed by both O 2 -induced Fe 2+ oxidation and direct reduction of O 2 by electrons on the conduction band in the presence of the poorly crystalline Fh. These findings demonstrate that sunlight may significantly accelerate the degradation of organic pollutants in the presence of iron (hydr)oxides., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Numerous application of pyrethroid insecticides has led to their accumulation in the environment, threatening ecological environment and human health. Its fate in the presence of iron-bearing minerals and natural organic matter under light irradiation is still unknown. We found that goethite (Gt) and humic acid (HA) could improve the photodegradation of bifenthrin (BF) in proper concentration under light irradiation. The interaction between Gt and HA may further enhance BF degradation. On one hand, the adsorption of HA on Gt may decrease the photocatalytic activity of HA through decreasing HA content in solution and sequestering the functional groups related with the production of reactive species. On the other hand, HA could improve the photocatalytic activity of Gt through extending light absorption, lowing of bandgap energy, hindering the recombination of photo-generated charges, and promoting the oxidation and reduction reaction on Gt surface. The increased oxygen vacancies on Gt surface along with the reduction of trivalent iron and the nucleophilic attack of hole to surface hydroxyl group contributed to the increasing photocatalytic activity of Gt. Electron paramagnetic resonance and quenching studies demonstrated that both oxidation species, such as hydroxyl radical (•OH) and singlet oxygen ( 1 O 2 ), and reducing species, such as hydrogen atoms (H•) and superoxide anion radical (O 2 •- ), contributed to BF degradation in UV-Gt-HA system. Mass spectrometry, ion chromatography, and toxicity assessment indicated that less toxic C 23 H 22 ClF 3 O 3 (OH-BF), C 9 H 10 ClF 3 O (TFP), C 14 H 14 O 2 (OH-MBP), C 14 H 12 O 2 (MBP acid), C 14 H 12 O 3 (OH-MBP acid), and chloride ions were the main degradation products. The production of OH-BF, MPB, and TFP acid through oxidation and the production of MPB and TFP via reduction were the two primary pathways of BF degradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Iron (hydr)oxides and humic acid (HA) are important active components in soils and usually coexist in the environment. The effects of HA on the adsorption and subsequent immobilization of phosphate on iron (hydr)oxide surface are of great importance in studies of soil fertility and eutrophication. In this study, two types of goethite with different particle sizes were prepared to investigate the phosphate adsorption behaviors and complexation mechanisms in the absence or presence of HA by combining multiple characterization and modeling studies. The adsorption capacity of micro- (M-Goe) and nano-sized goethite (N-Goe) for phosphate was 2.02 and 2.04 μmol/m 2 , which decreased by ∼25% and ∼45% in the presence of 100 and 200 mg/L HA, respectively. Moreover, an increase in equilibrium phosphate concentration significantly decreased the adsorption amount of goethite for HA. Charge distribution-multisite surface complexation (CD-MUSIC) and natural organic matter-charge distribution (NOM-CD) modeling identified five phosphate complexes and their corresponding affinity constants (logK P ). Among these phosphate complexes, FeOPO 2 OH, (FeO) 2 PO 2 , and (FeO) 2 POOH species were predominant complexes on the surface of both M-Goe and N-Goe across a wide range of pH and initial phosphate concentrations. The presence of HA had little effect on the coordination mode and logK P of phosphate on goethite surface. These results and the obtained model parameters shed new lights on the interfacial reactivity of phosphate at the goethite-water interface in the presence of HA, and may facilitate further prediction of the environmental fate of phosphate in soils and sediments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Monitoring acetylcholinesterase (AChE) is crucial in clinical diagnosis and drug screening. Traditional methods for detecting AChE usually require the addition of intermediates like acetylthiocholine, which complicates the detection process and introduces interference risks. Herein, we develop a direct colorimetric assay based on alkaline iron formate nanosheets (Fe(HCOO) 2.6 (OH) 0.3 ·H 2 O NSs, Fef NSs) for the detection of AChE without any intermediates. The as-prepared Fef NSs exhibit oxidase-like activity, catalyzing the generation of O 2 ·- , 1 O 2 and ·OH, which leads to a color change from colorless to blue when exposed to 3,3',5,5'-tetramethylbenzidine. AChE directly inhibits the oxidase-like activity of Fef NSs, resulting in a hindered color reaction, enabling the detection of AChE. The biosensor has a linear detection range of 0.1-30 mU/mL, with a minimum detection limit of 0.0083 mU/mL (S/N = 3), representing a 100-fold improvement in detection sensitivity over the traditional Ellman's method. Satisfactory results were obtained when analyzing real AChE samples. Attractively, a method for the quantitative detection of AChE by a smartphone is established based on the Fef NSs. This method enables instant acquisition of AChE concentrations, achieving real-time visualized detection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Schwertmannite (Sch) is considered as an effective remover of Chromium (Cr) due to its strong affinity for toxic Cr species. Since the instability of Sch, the environmental fate of Cr deserves attention during the transformation of Sch into a more stable crystalline phase. The ubiquitous manganese(II) (Mn(II)) probably affects the transformation of Sch and thus the environmental fate of Cr. Therefore, this study investigated the impact of Mn(II) on the transformation of Cr-absorbed Sch (Cr-Sch) and the associated behavior of SO 4 2- and Cr. We revealed that the transformation products of Cr-Sch at pH 3.0 and 7.0 were goethite and Sch, respectively. The presence of Mn(II) weakened the crystallinity of the transformation products, and the trend was positively correlated with the concentration of Mn(II). However, Mn(II) changed the transformation products of Cr-Sch from hematite to goethite at pH 10.0. Mn(II) replaced Fe(III) in the mineral structures or formed Mn-O complexes with surface hydroxyl groups (-OH), thereby affecting the transformation pathways of Sch. The presence of Mn(II) enhanced the immobilization of Cr on minerals at pH 3.0 and 7.0. Sch is likely to provide an channel for electron transfer between Mn(II) and Cr(VI), which promotes the reduction of Cr(VI). Meanwhile, Mn(Ⅱ) induced more -OH production on the surface of secondary minerals, which played an important role in increasing the Cr fixation. In addition, part of the Mn(Ⅱ) was oxidized to Mn(Ⅲ)/Mn(Ⅳ) at pH 3.0 and pH 7.0. This study helps to predict the role of Mn(II) in the transformations of Cr-Sch in environments and design remediation strategies for Cr contamination., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Dissimilatory iron-reducing bacteria (DIRB) affect the geochemical cycling of redox-sensitive pollutants in anaerobic environments by controlling the transformation of Fe morphology. The anaerobic oxidation of antimonite (Sb(III)) driven by DIRB and Fe(III) oxyhydroxides interactions has been previously reported. However, the oxidative species and mechanisms involved remain unclear. In this study, both biotic phenomenon and abiotic verification experiments were conducted to explore the formed oxidative intermediates and related processes that lead to anaerobic Sb(III) oxidation accompanied during dissimilatory iron reduction. Sb(V) up to 2.59 μmol L -1 combined with total Fe(II) increased to 188.79 μmol L -1 when both Shewanella oneidensis MR-1 and goethite were present. In contrast, no Sb(III) oxidation or Fe(III) reduction occurred in the presence of MR-1 or goethite alone. Negative open circuit potential (OCP) shifts further demonstrated the generation of interfacial electron transfer (ET) between biogenic Fe(II) and goethite. Based on spectrophotometry, electron spin resonance (ESR) test and quenching experiments, the active ET production labile Fe(III) was confirmed to oxidize 94.12% of the Sb(III), while the contribution of other radicals was elucidated. Accordingly, we proposed that labile Fe(III) was the main oxidative species during anaerobic Sb(III) oxidation in the presence of DIRB and that the toxicity of antimony (Sb) in the environment was reduced. Considering the prevalence of DIRB and Fe(III) oxyhydroxides in natural environments, our findings provide a new perspective on the transformation of redox sensitive substances and build an eco-friendly bioremediation strategy for treating toxic metalloid pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Ferrate (Fe(VI): HFeO 4 - /FeO 4 2- ), a potent oxidant, has been investigated as an alternative chemical disinfectant in water treatment due to its reduced production of disinfection by-products. In this study, we assessed the disinfecting ability of potassium ferrate against a variety of microorganisms, including waterborne pathogens, under varying pH and water temperature conditions. We presented CT values, a metric of ferrate concentrations (C) and contact time (T), to quantify microbial inactivation rates. Among the tested microorganisms, human adenovirus was the least resistant to ferrate, followed by waterborne bacteria such as Escherichia coli and Vibrio cholerae , and finally, the protozoan parasite Giardia duodenalis . We further investigated the impact of two pH values (7 and 8) and two temperatures (5 and 25 °C) on microbial inactivation rates, observing that inactivation rates increased with lower pH and higher temperature. In addition to showcasing ferrate's capacity to effectively inactivate a range of the tested microorganisms, we offer a ferrate CT table to facilitate the comparison of the effectiveness of various disinfection methods., Competing Interests: The authors declare there is no conflict., (© 2024 The Authors This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).)

Inorganic binders like bentonite, used for pelletization of low-grade iron ore, generate iron ore slimes with comparatively high silica and alumina content necessitating extra steps for their removal during iron making process. This demands the usage of organic binders as full or partial replacement of bentonite for iron ore pelletization. In this work, adsorption of organic binders with saccharides skeleton and -H, -OH, -CH 2 OH and -CH 2 CH 2 OH as polar substituents, on goethite surface was studied using density functional theory, molecular dynamics and machine learning. It was observed that adsorption energy of binders on goethite surface had weak dependence on number of hydrogen bonds between them. With this favorable interaction in mind, a library containing 64 organic binders was constructed and adsorption energy of 30 of these binders was computed using molecular dynamics, followed by training of a linear regression model, which was then used to predict the adsorption energy of rest of the binders in the library. It was found that the introduction of -CH 2 CH 2 OH at R2 position resulted in statistically significant higher adsorption energy. Binder34 and Binder44 were identified as viable candidates for both goethite and hematite ore pelletization and adsorption of their n-mers on goethite and hematite surfaces was also quantified., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Niladri Patra reports financial support was provided by Tata Steel Ltd Jamshedpur., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study aimed to develop surface complexation modeling-machine learning (SCM-ML) hybrid model for chromate and arsenate adsorption on goethite. The feasibility of two SCM-ML hybrid modeling approaches was investigated. Firstly, we attempted to utilize ML algorithms and establish the parameter model, to link factors influencing the adsorption amount of oxyanions with optimized surface complexation constants. However, the results revealed the optimized chromate or arsenate surface complexation constants might fall into local extrema, making it unable to establish a reasonable mapping relationship between adsorption conditions and surface complexation constants by ML algorithms. In contrast, species-informed models were successfully obtained, by incorporating the surface species information calculated from the unoptimized SCM with the adsorption condition as input features. Compared with the optimized SCM, the species-informed model could make more accurate predictions on pH edges, isotherms, and kinetic data for various input conditions (for chromate: root mean square error (RMSE) on test set = 5.90 %; for arsenate: RMSE on test set = 4.84 %). Furthermore, the utilization of the interpretable formula based on Local Interpretable Model-Agnostic Explanations (LIME) enabled the species-informed model to provide surface species information like SCM. The species-informed SCM-ML hybrid modeling method proposed in this study has great practicality and application potential, and is expected to become a new paradigm in surface adsorption model., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Due to the anthropogenic increase of atmospheric CO 2 emissions, humanity is facing the negative effects of rapid global climate change. Both active emission reduction and carbon dioxide removal (CDR) technologies are needed to meet the Paris Agreement and limit global warming to 1.5 °C by 2050. One promising CDR approach is coastal enhanced weathering (CEW), which involves the placement of sand composed of (ultra)mafic minerals like olivine in coastal zones. Although the large-scale placement of olivine sand could beneficially impact the planet through the consumption of atmospheric CO 2 and reduction in ocean acidification, it may also have physical and geochemical impacts on benthic communities. The dissolution of olivine can release dissolved constituents such as trace metals that may affect marine organisms. Here we tested acute and chronic responses of marine invertebrates to olivine sand exposure, as well as examined metal accumulation in invertebrate tissue resulting from olivine dissolution. Two different ecotoxicological experiments were performed on a range of benthic marine invertebrates (amphipod, polychaete, bivalve). The first experiment included acute and chronic survival and growth tests (10 and 20 days, respectively) of olivine exposure while the second had longer (28 day) exposures to measure chronic survival and bioaccumulation of trace metals (e.g. Ni, Cr, Co) released during olivine sand dissolution. Across all fauna we observed no negative effects on acute survival or chronic growth resulting solely from olivine exposure. However, over 28 days of exposure, the bent-nosed clam Macoma nasuta experienced reduced burrowing and accumulated 4.2 ± 0.7 μg g ww -1 of Ni while the polychaete Alitta virens accumulated 3.5 ± 0.9 μg g ww -1 of Ni. No significant accumulation of any other metals was observed. Future work should include longer-term laboratory studies as well as CEW field studies to validate these findings under real-world scenarios., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Emilia Jankowska, Francesc Montserrat, Stephen J. Romaniello, Nathan G. Walworth, Grace M. Andrews reports financial support was provided by Cisco Foundation Global Impact Grant. Emilia Jankowska, Francesc Montserrat, Stephen J. Romaniello, Nathan G. Walworth, Grace M. Andrews reports financial support was provided by Grantham Foundation for the Protection of the Environment. Emilia Jankowska, Francesc Montserrat, Stephen J. Romaniello, Nathan G. Walworth, Grace M. Andrews reports financial support was provided by Treadright Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Simultaneously stabilizing of arsenic (As) and cadmium (Cd) in co-contaminated soil presents substantial challenges due to their contrasting chemical properties. Schwertmannite (Sch) is recognized as a potent adsorbent for As pollution, with alkali modification showing promising results in the simultaneous immobilization of both As and Cd. This study systematically investigated the long-term stabilization efficacy of alkali-modified Sch in Cd-As co-contaminated farmland soil over a 200-day flooding-drying period. The results revealed that As showed significant mobility in flooded conditions, whereas Cd exhibited increased soil availability under drying phases. The addition of Sch did not affect the trends in soil pH and Eh fluctuations; nonetheless, it led to an augmentation in the levels of amorphous iron oxides and SO 4 2- concentration in soil pore water. At a dosage of 0.5% Sch, there was a notable decrease in the mobility and soil availability of As and Cd under both flooding (34.5% and 53.6% at Day 50) and drying conditions (27.0% and 29.4% at Day 130), primarily promoting the transformation of labile metal(loid) fraction into amorphous iron oxide-bound forms. Throughout the flooding-drying treatment period, Sch maintained stable mineral morphology and mineralogical phase, highlighting its long-term stabilization effect. The findings of this study emphasize the promising application of Sch-based soil remediation agents in mitigating the challenges arising from As-Cd co-contamination. Further research is warranted to explore their application in real farmland settings and their impact on the uptake of toxic metal(loid)s by plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Arsenopyrite and pyrite often coexist in metal deposits and tailings, thus simultaneous bioleaching of both sulfides has economic (as well as environmental) significance. Important targets in bio-oxidation operations are high solubilization rates and minimized accumulation of Fe(III)/As-bearing secondary products. This study investigated the role of pyrite bioleaching in the enhancement of arsenopyrite dissolution. At a pyrite to arsenopyrite mass ratio of 1:1, 93.6% of As and 93.0% of Fe were solubilized. The results show that pyrite bio-oxidation can promote arsenopyrite dissolution, enhance S 0 bio-oxidation, and inhibit the formation of jarosites, tooeleite, and amorphous ferric arsenate. The dry weight of the pyrite & arsenopyrite residue was reduced by 95.1% after bioleaching, compared to the initial load, while only 5% weight loss was observed when pyrite was absent. A biofilm was formed on the arsenopyrite surface in the presence of pyrite, while a dense passivation layer was observed in the absence of pyrite. As(III) (as As 2 O 3 ) was a dominant As species in the pyrite & arsenopyrite residue. Novel and detailed findings are presented on arsenopyrite bio-dissolution in the presence of pyrite, and the presented approach could contribute to the development of novel cost-effective extractive bioprocesses. ENVIRONMENTAL IMPLICATION: The oxidation of arsenopyrite presents significant environmental hazards, as it can contribute to acid mine drainage generation and arsenic mobilization from sulfidic mine wastes. Bioleaching is a proven cost-effective and environmentally friendly extractive technology, which has been applied for decades in metal recovery from minerals or tailings. In this work, efficient extraction of arsenic from arsenopyrite bioleaching was presented through coupling the process with bio-oxidation of pyrite, resulting in lowered accumulation of hazardous and metastable Fe(III)/As-bearing secondary phases. The results could help improve current biomining operations and/or contribute to the development of novel cost-effective bioprocesses for metal extraction., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The widespread used organoarsenicals have drawn attention for decades due to their potential environment risks. In this study, a heterogeneous system of goethite/oxalate irradiated using UVA light (λ = 365 nm) was applied for the removal of ASA, a kind of organoarsenicals used in animal feeding operations as additives, from the aqueous phase through photodegradation. Results showed that the presence of 5 mM of oxalate significantly enhanced the photodegradation efficiency of ASA in the 0.1 g/L of goethite suspended system from 28 to ~100% within 180 min reaction at pH 5. Acid conditions favored the photoreaction rate, compared with neutral and basic conditions. This reaction process was also influenced by the initial concentration of oxalate and ASA. Furthermore, the mechanism study was conducted by quenching experiments and revealed the important roles of ·OH in the degradation of ASA in the goethite/oxalate/UVA system. By analyzing the reaction products, both inorganic arsenic (As(III) and As(V)) and ammonia were detected during the photodegradation of ASA. These findings help to gain a better understanding of the geochemical behavior of ASA in surface water and can also provide a potential treatment method for the organoarsenicals contaminated water., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In contaminated water and soil, little is known about the role and mechanism of the biometabolic molecule siderophore desferrioxamine-B (DFO) in the biogeochemical cycle of uranium due to complicated coordination and reaction networks. Here, a joint experimental and quantum chemical investigation is carried out to probe the biomineralization of uranyl (UO 2 2+ , referred to as U(VI) hereafter) induced by Shewanella putrefaciens (abbreviated as S. putrefaciens ) in the presence of DFO and Fe 3+ ion. The results show that the production of mineralized solids {hydrogen-uranium mica [H 2 (UO 2 ) 2 (PO 4 ) 2 ·8H 2 O]} via S. putrefaciens binding with UO 2 2+ is inhibited by DFO, which can both chelate preferentially UO 2 2+ to form a U(VI)-DFO complex in solution and seize it from U(VI)-biominerals upon solvation. However, with Fe 3+ ion introduced, the strong specificity of DFO binding with Fe 3+ causes re-emergence of biomineralization of UO 2 2+ {bassetite [Fe(UO 2 ) 2 (PO 4 ) 2 ·8(H 2 O)]} by S. putrefaciens , owing to competitive complexation between Fe 3+ and UO 2 2+ for DFO. As DFO possesses three hydroxamic functional groups, it forms hexadentate coordination with Fe 3+ and UO 2 2+ ions via these functional groups. The stability of the Fe 3+ -DFO complex is much higher than that of U(VI)-DFO, resulting in some DFO-released UO 2 2+ to be remobilized by S. putrefaciens . Our finding not only adds to the understanding of the fate of toxic U(VI)-containing substances in the environment and biogeochemical cycles in the future but also suggests the promising potential of utilizing functionalized DFO ligands for uranium processing.

Debye temperatures of α -Sn x Fe 1- x OOH nanoparticles ( x = 0, 0.05, 0.10, 0.15 and 0.20, abbreviated as Sn100 x NPs) prepared by hydrothermal reaction were estimated with 57 Fe- and 119 Sn-Mössbauer spectra measured by varying the temperature from 20 to 300 K. Electrical properties were studied by solid-state impedance spectroscopy (SS-IS). Together, the charge-discharge capacity of Li- and Na-ion batteries containing Sn100 x NPs as a cathode were evaluated. 57 Fe-Mössbauer spectra of Sn10, Sn15, and Sn20 measured at 300 K showed only one doublet due to the superparamagnetic doublet, while the doublet decomposed into a sextet due to goethite at the temperature below 50 K for Sn 10, 200 K for Sn15, and 100 K for Sn20. These results suggest that Sn10, Sn15 and Sn20 had smaller particles than Sn0. On the other hand, 20 K 119 Sn-Mössbauer spectra of Sn15 were composed of a paramagnetic doublet with an isomer shift ( δ ) of 0.24 mm s -1 and quadrupole splitting (∆) of 3.52 mm s -1 . These values were larger than those of Sn10 ( δ : 0.08 mm s -1 , ∆: 0.00 mm s -1 ) and Sn20 ( δ : 0.10 mm s -1 , ∆: 0.00 mm s -1 ), suggesting that the Sn IV -O chemical bond is shorter and the distortion of octahedral SnO 6 is larger in Sn15 than in Sn10 and Sn20 due to the increase in the covalency and polarization of the Sn IV -O chemical bond. Debye temperatures determined from 57 Fe-Mössbauer spectra measured at the low temperature were 210 K, 228 K, and 250 K for Sn10, Sn15, and Sn20, while that of α -Fe 2 O 3 was 324 K. Similarly, the Debye temperature of 199, 251, and 269 K for Sn10, Sn15, and Sn20 were estimated from the temperature-dependent 119 Sn-Mössbauer spectra, which were significantly smaller than that of BaSnO 3 (=658 K) and SnO 2 (=382 K). These results suggest that Fe and Sn are a weakly bound lattice in goethite NPs with low crystallinity. Modification of NPs and addition of Sn has a positive effect, resulting in an increase in DC conductivity of almost 5 orders of magnitude, from a σ DC value of 9.37 × 10 -7 (Ω cm) -1 for pure goethite Sn (Sn0) up to DC plateau for samples containing 0.15 and 0.20 Sn (Sn15 and Sn20) with a DC value of ~4 × 10 -7 (Ω cm) -1 @423 K. This non-linear conductivity pattern and levelling at a higher Sn content suggests that structural modifications have a notable impact on electron transport, which is primarily governed by the thermally activated via three-dimensional hopping of small polarons (SPH). Measurements of SIB performance, including the Sn100 x cathode under a current density of 50 mA g -1 , showed initial capacities of 81 and 85 mAh g -1 for Sn0 and Sn15, which were larger than the others. The large initial capacities were measured at a current density of 5 mA g -1 found at 170 and 182 mAh g -1 for Sn15 and Sn20, respectively. It is concluded that tin-goethite NPs are an excellent material for a secondary battery cathode and that Sn15 is the best cathode among the studied Sn100 x NPs.

In this study, we developed prediction models for the adsorption of divalent and trivalent oxyanions on goethite based on machine learning algorithms. After verifying the reliability of the models, the importance of goethite specific surface area (SSA) and the average oxyanion adsorption capacities of goethite with different SSAs were calculated by shapley additive explanations (SHAP) importance analysis and partial dependence (PD) analysis. Despite there were differences in the feature importance of divalent and trivalent oxyanions, the contribution of goethite's SSA to the adsorption amount ranked the fourth based on SHAP importance, indicating SSA played the important role in oxyanion adsorption. Meanwhile, the PD values of SSA and the optimized complexation constants from surface complexation modeling (SCM) both indicated a non-monotonic relationship between the goethite with different SSA and its oxyanions binding capacity. When the total site concentration and crystal face composition were used as the machine learning model input features, the SHAP importance values of crystal faces and the PD decomposition results indicated that the (001) face showed the crucial influence on oxyanions adsorption amount. These findings demonstrated the important role of crystal face composition in goethite's adsorption ability, and provided a theoretical explanation for the variations of oxyanions adsorption amount on different SSA goethite., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Abundant iron and sulfate resources are present in acid mine drainage. The synthesis of schwertmannite from AMD rich in iron and sulfate could achieve the dual objectives of resource recovery and wastewater purification. However, schwertmannite cannot emerge spontaneously due to the Gibbs free energy greater than 0. This results in the iron and sulfate in AMD only being able to use the energy generated by oxidation in the coupling reaction to promote the formation of minerals, but this only achieved partial mineralization, which limited the remediation of AMD through mineralization. In order to clarify the mechanism of iron and sulfate removal by the formation of schwertmannite in AMD, kinetic and thermodynamic parameters were crucial. This work used H 2 O 2 oxidation of Fe 2+ as a coupling reaction to promote the formation of schwertmannite from 64.4% of iron and 15.7% of sulfate in AMD, and determined that 99.7% of the iron and 89.9% of sulfate were immobilized in the schwertmannite structural, and only a small fraction was immobilized by the adsorption of schwertmannite, both of which were consistent with second-order kinetics models. The thermodynamic data suggested that reducing the concentration of excess sulfate ions or increasing the energy of the system may allow more iron and sulfate to be immobilized by forming schwertmannite. Experimental verification using the reaction of potassium bicarbonate with the acidity in solution to increase the energy in the system showed that the addition of potassium bicarbonate effectively promoted the formation of schwertmannite from Fe 3+ and SO 4 2- . It provided a theoretical and research basis for the direct synthesis of schwertmannite from Fe 3+ and SO 4 2- rich AMD for the removal of contaminants from water and the recovery of valuable resources., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Perfluorooctanesulfonate (PFOS) has become a major concern due to its widespread occurrence in the environment and severe toxic effects. In this study, we investigate PFOS sorption on goethite surfaces under different water chemistry conditions to understand the impact of variable groundwater chemistry. Our investigation is based on multiple lines of evidence, including (i) a series of sorption experiments with varying pH, ionic strength, and PFOS initial concentration, (ii) IR spectroscopy analysis, and (iii) surface complexation modeling. PFOS was found to bind to goethite through a strong hydrogen-bonded (HB) complex and a weaker outer-sphere complex involving Na + coadsorption (OS-Na + ). The pH and ionic strength of the solution had a nontrivial impact on the speciation and coexistence of these surface complexes. Acidic conditions and low ionic strength promoted hydrogen bonding between the sulfonate headgroup and protonated hydroxo surface sites. Higher electrolyte concentrations and pH values hindered the formation of strong hydrogen bonds upon the formation of a ternary PFOS-Na + -goethite outer-sphere complex. The findings of this study illuminate the key control of variable solution chemistry on PFOS adsorption to mineral surfaces and the importance to develop surface complexation models integrating mechanistic insights for the accurate prediction of PFOS mobility and environmental fate.

The interactions between organic pollutants and iron minerals play an important role in their environmental fate. In this study, the effects of low-molecular-weight organic acids (LMWOAs) on the adsorption and degradation of tetracycline (TC) on goethite were investigated. Tartaric acid (TA) was taken as the representative of LMWOAs to study the influencing mechanism through batch experiments and microscale characterization. In addition, the properties of TC-TA clusters under different pHs were determined by density functional theory (DFT) calculations. The results showed that all five LMWOAs inhibited TC adsorption and degradation. The preferential adsorption of TA on goethite changed TC adsorption from inner spherical to outer spherical complexation and mainly inhibited TC adsorption and degradation of the singly coordinated hydroxyl group. TC degradation rate decreased from 0.0287 to 0 h -1 in the first stage. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results showed that TA could influence the interactions of amide groups, C = O on the A-ring, and dimethylamino group of TC with goethite, and the formation of ≡Fe(II) was inhibited. In addition to competing for the effective sites, the effects of complexation between TA and TC in solution should be considered. According to DFT calculations, hydrogen bonds could be formed between the carboxyl group of TA and the H atom of TC at different pH. These findings can provide evidence for estimating the contribution of adsorption and degradation to TC removal by iron oxides with the coexistence of LMWOAs in a soil-water environment., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

NifB, a radical S-adenosylmethionine (SAM) enzyme, is pivotal in the biosynthesis of the iron-molybdenum cofactor (FeMo-co), commonly referred to as the M-cluster. This cofactor, located within the active site of nitrogenase, is essential for the conversion of dinitrogen (N 2 ) to NH 3 . Recognized as the most intricate metallocluster in nature, FeMo-co biosynthesis involves multiple proteins and a sequence of steps. Of particular significance, NifB directs the fusion of two [Fe 4 S 4 ] clusters to assemble the 8Fe core, while also incorporating an interstitial carbide. Although NifB has been extensively studied, its molecular mechanisms remain elusive. In this review, we explore recent structural analyses of NifB and provide a comprehensive overview of the established catalytic mechanisms. We propose prospective directions for future research, emphasizing the relevance to biochemistry, agriculture, and environmental science. The goal of this review is to lay a solid foundation for future endeavors aimed at elucidating the atomic details of FeMo-co biosynthesis.

Heterogeneous crystallization is a common occurrence during the formation of solid wastes. It leads to the encapsulation of valuable/hazardous metals within the primary phase, presenting significant challenges for waste treatment and metal recovery. Herein, we proposed a novel method involving the in-situ formation of a competitive substrate during the precipitation of jarosite waste, which is an essential process for removing iron in zinc hydrometallurgy. We observed that the in-situ-formed competitive substrate effectively inhibits the heterogeneous crystallization of jarosite on the surface of anglesite, a lead-rich phase present in the jarosite waste. As a result, the iron content on the anglesite surface decreases from 34.8% to 1.65%. The competitive substrate was identified as schwertmannite, characterized by its loose structure and large surface area. Furthermore, we have elucidated a novel mechanism underlying this inhibition of heterogeneous crystallization, which involves the local supersaturation of jarosite caused by the release of ferric and sulfate ions from the competitive substrate. The local supersaturation promotes the preferential heterogeneous crystallization of jarosite on the competitive substrate. Interestingly, during the formation of jarosite, the competitive substrate gradually vanished through a dissolution-recrystallization process following the Ostwald rule, where a metastable phase slowly transitions to a stable phase. This effectively precluded the introduction of impurities and reduced waste volume. The goal of this study is to provide fresh insights into the mechanism of heterogeneous crystallization control, and to offer practical crystallization strategies conducive to metal separation and recovery from solid waste in industries., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Extraction of bioactive compounds from Withania somnifera roots was studied using sodium acetate-glycerol deep eutectic solvent (DES) and two techniques ultrasound-assisted extraction (UAE) and heat-assisted extraction (HAE) under response surface methodology (RSM). For UAE and HAE, total phenolic content (TPC, mg gallic acid equivalents per g dry weight (mg GAE g-1 DW)), total flavonoid content (TFC, mg rutin equivalents g-1 DW (mg RE g-1 DW)), radical scavenging activity (RSA, mg AAE (ascorbic acid equivalents) g-1 DW), and iron chelating activity (ICA, mg EDTAE (ethylenediaminetetraacetate equivalents) g-1 DW%) were 6.51, 6.08, 12.56, and 3.57, respectively, and 3.33, 3.98. 6.57 and 2.48, respectively. For UAE, the optimal conditions were a DES concentration of 50 %, temperature of 60 °C, and time of 20 min, and for HAE, a DES concentration of 60 %, temperature of 60 °C, and time of 75 min. The discovered models were strongly supported by the validation experiments. UAE was more efficient and less time-consuming for extracting phytoconstituents of the W. somnifera than HAE.