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Mycosorption is a promising alternative for removing heavy metal pollutants present at dilute concentrations in various contaminated water. Here, we describe an exciting solution for metal removal from competitive and non-competitive simulated aqueous systems by various mycosorbents. Herein, 41 fungi were selected based on their fast growth rate and high biomass yield to produce effective mycosorbents. These dried fungal biomasses were tested against five different single metals with maximum metal concentration at 25 mg/L and 50 mg of biomass. AD1 to AD7 showed maximum metal sorption proficiencies in the 40–90% range within 30 min of contact time in a non-competitive system. Equilibrium constant (Qeq) values fall in the 10.75 to 15.0 mg/g range for all these mycosorbents. Scarce studies have investigated competitive sorption. This approach sheds light on competitive metal sorption from two different dilute concentrations regardless of metal toxicity and tolerance capacity of mycosorbents. Around 60–96% Cr and Pb biosorption was achieved at an initial metal concentration of 5 mg/L and between 15 and 42% Cd, Ni and Cu. In the case of 25 mg/L of initial metal concentration, 70 to 99% of Pb and Cr, 21–54% Cd, Ni and Cu biosorption was obtained in 2 h of contact time. The maximum sorption capacities ranged from 0.4 to 5.0 mg/g in 5 mg/L and 5.5 to 24.7 mg/g in 25 mg/L metal concentrations in competitive sorption. This result presents a novel approach to applying dried mycosorbents to remove five metals at a time present in a dilute concentration in wastewater where synthetic sorbents are ineffective. [ABSTRACT FROM AUTHOR]

Androgens and glucocorticoids are prevalent in the environment, posing significant risks to human and ecological health. However, their sorption behaviors in sediments remain poorly understood. This study investigated the sorption characteristics of two androgens and two glucocorticoids, both individually and in binary mixtures, in freshwater sediment. The results showed that the sorption of these four steroids aligned more closely with pseudo-second-order kinetics. Higher initial concentrations resulted in larger equilibrium sorption capacities and smaller sorption rate constants except DEX. The sorption isotherms were better described by the Langmuir model, with androgens exhibiting smaller adsorption capacities compared to glucocorticoids, ranging from a minimum of 70.04 mg/kg for androstenedione to a maximum of 322.3 mg/kg for cortisone. In binary adsorbate systems, the coexistence of androstenedione and methyltestosterone exhibited synergistic sorption, as did the coexistence of androstenedione and dexamethasone. Dexamethasone competed with either cortisone or methyltestosterone when they coexisted. This study enhances the understanding of the environmental fate of steroid hormone and provides theoretical support for accurately assessing their ecological risks. [ABSTRACT FROM AUTHOR]

The anions and cations in agricultural additives have crucial impacts on the retention of toxic heavy metals (HMs) in soil. However, the influence of these ions on the adsorption and desorption of Cd, Cr, and Cu in soil has not been clarified in previous studies. This study investigated the adsorption behavior of HMs, common anions, and dissolved organic matter (DOM) in alkaline soil from farmland under different experimental conditions. Nitrates, sulfates, and chlorides were used as HM sources to investigate the effects of different experimental anion environments on batch adsorption experiments and fluorescence quenching titration experiments. Batch sorption experiments showed that the sorption of Cd2+ was inhibited by the concomitant presence of Cr3+ and Cu2+, and the presence of Cl− and SO42− inhibited the binding of HMs to the soil matrix compared to NO3−. The fluorescence quenching titration with HMs suggested that SO42− significantly enhances the binding ability of Cr3+ to DOM in solution, which may be the reason SO42− inhibited Cr3+ retention in soil. These results provide detailed insights into the interactions of HMs with DOM and anions, which is of great significance for the targeted application of pesticides and HMs' transport and removal in farmland soils. [ABSTRACT FROM AUTHOR]

Purpose: The competitive sorption of arsenite, As(III), and antimonite, Sb(III) on mackinawite (FeS) was investigated, so as to better understand the influence between As(III) and Sb(III) in anaerobic water, soil, or sediment systems rich in FeS. Methods: FeS was synthesized and As(III) and Sb(III) were simultaneously or sequentially added into the FeS suspensions, so as to simulate the competitive sorption of As(III) and Sb(III) on the surface of FeS particles when As(III) and Sb(III) were parallelly sorbed or As(III) sorption was priorly aged. Results: It was found that As(III) uptake by FeS could be significantly inhibited by Sb(III) at pH 7.0. When As(III) (initial concentration: 1 mg L−1) and Sb(III) were simultaneously added into FeS suspensions at pH 7.0, the presence of Sb(III) reduced the As(III) uptake by FeS from 51.8% (no Sb(III) added) to 22.7% (1 mg L−1 Sb(III) added) and to 6.9% (5 mg L−1 Sb(III) added), respectively. In contrast, As(III) uptake by FeS was only slightly inhibited at pH 5.5 and not inhibited at pH 9.0. It was postulated that the competitive sorption of As(III) and Sb(III) was primarily associated with the binding of As(III) and Sb(III) to FeS at the sulfur sites and the different chalcophility of Sb(III) and As(III) led to the significant replacement of As(III) by Sb(III) at pH 7.0. It was also found that aging of As(III) sorption significantly reduced the amount of As(III) that was outcompeted by Sb(III). Conclusion: This study revealed the competitive sorption of As(III) and Sb(III) on FeS particles, and implicated the importance of competitive sorption in evaluating the mobilization or immobilization of arsenic or antimony in iron- and sulfur-rich anaerobic lake sediments or soils. [ABSTRACT FROM AUTHOR]

[Display omitted] • Competitive sorption of CH 4 and CO 2 from a pre-mixed binary gas mixture was studied. • Displacement effects of CO 2 on pre-adsorbed CH 4 in coal were investigated. • Improved Langmuir model for mixture gas sorption was proposed and validated. • Coal selectivity for CO 2 and CH 4 under multicomponent scenarios was compared. Geological carbon storage, particularly within coal seams, is recognized as a viable strategy for achieving net-zero emissions. However, following CO₂ injection into the coal seam, limited studies have addressed the competitive sorption dynamics of CH₄ and CO₂ on coal, despite the natural presence of CH₄ in these formations. In this work, sorption experiments were conducted using two types of coal: sub-bituminous coal and anthracite. Initially, pure CH 4 and CO 2 gases were employed to conduct individual sorption tests. Subsequently, the competitive sorption of CH 4 and CO 2 was evaluated using pre-mixed binary gas mixtures with varying CH 4 /CO 2 ratios. Further, the displacement effect of CO 2 on CH 4 was investigated by injecting CO 2 into coal samples that had been pre-adsorbed with CH 4. The data reveal that, for both coals, the ideal selectivity calculated from pure gas measurements underestimates the corresponding values from real multicomponent systems. Anthracite demonstrates a higher selectivity for CO₂ over CH₄ during both adsorption and desorption processes when compared to the ideal selectivity calculated from pure gas sorption data. Conversely, the sub-bituminous coal initially shows lower selectivity for CO₂ than for CH₄ during adsorption, but this trend reverses and intensifies during desorption. If competitive sorption effects are neglected, coal selectivity for CO₂ over CH₄ under the examined conditions would be underestimated by a factor of 1.5 to 2.5. Due to the competitive sorption effects between CH₄ and CO₂, the Langmuir equilibrium constants for gas mixtures are influenced by compositional changes, leading to dynamic deviations from those observed under pure gas conditions. This finding contrasts with the traditional extended Langmuir model, which presumes that the equilibrium constants remain unchanged regardless of gas composition. In addition, the displacement study underscores the efficacy of CO 2 in displacing CH 4 , with higher CO 2 ratios intensifying displacement effects. The study highlights the substantial impact of real multicomponent scenarios on coal selectivity for CO₂ and CH₄, offering deeper insights into predicting competitive sorption behavior between CO₂ and CH₄ during CO₂-enhanced coalbed methane recovery and carbon storage processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Established the "core- membrane" architecture of DES synthesized in situ on ZIF-8. • ZIF-8 morphology and pore features are effectively maintained after DES growth. • Modified ZIF-8 displays a 4-fold increase in sorption capacity at 1 bar. • CO 2 /N 2 separation coefficient increases by 13.71 times compared to pristine ZIF-8. • The "core- membrane" structure exhibits excellent thermal and cyclic stability. To enhance CO 2 sorption efficiency under low-pressure conditions and effectively compete with N 2 sorption in flue gas, modifications are implemented aimed at improving the adsorption capacity and selectivity of ZIF-8, renowned for their robust stability. Deep eutectic solvent (DES) comprising tetraethylammonium chloride (TEAC), tetrapropylammonium chloride (TPAC), and tetrabutylammonium bromide (TBAB) as hydrogen-bond acceptors, along with ethanolamine (MEA) as the hydrogen-bond donor, were meticulously prepared for this purpose. ZIF-8 underwent modification through DES loading, resulting in the distinctive emergence of a "core-membrane" structure. Characterization revealed that the DES effectively adhered to the surface of ZIF-8 in a membrane-like structure, without altering the chemical structure or pore size of ZIF-8. The most significant enhancement in sorption capacity was observed with TPAC&MEA modification. Considering the presence of N 2 partial pressure in the flue gas, at 0.05 and 1 bar, the CO 2 adsorption capacities reached 1.92 and 3.03 mmol g−1, respectively, increasing 71.11 and 4.00 times compared to pristine ZIF-8. The ZIF-8 exhibited a CO 2 /N 2 separation coefficient of 72.77, which increased to a maximum of 997.50 after DES modification. Additionally, the modified material demonstrated exceptional cyclic and thermal stability during testing. This study significantly elevates the CO 2 adsorption capacity and selectivity of solid materials within the low-pressure range, providing pivotal support for CO 2 capture and decarbonization efforts. [ABSTRACT FROM AUTHOR]

• PFAS retention in unsaturated porous media is a function of concentration. • Competitive sorption between PFOS and PFOA can enhance PFOA mobility. • The Langmuir- Szyszkowski equations accurately predicted observed interfacial processes. • The Leverett thermodynamic model over-predicted air-water interfacial area. • Unsaturated experiments suggest that interfacial accumulation was rate limited. Among emerging contaminants, per- and polyfluoroalkyl substances (PFAS) have captured public attention based upon their environmental ubiquity and potential risks to human health. Due to their typical surface release conditions and amphiphilic properties, PFAS tend to sorb to soil and accumulate at the air-water interface within the vadose zone. These processes can result in substantial plume attenuation. Although there is a growing body of literature on vadose zone transport, few studies have explored PFAS mixture transport, particularly under conditions where nonlinear sorption processes are important. The present study aims to advance our understanding of PFAS transport in variably saturated porous media through integration of experiments and mathematical modeling. Experiments include batch studies to quantify sorption to the solid phase, interfacial tension (IFT) measurements to estimate adsorption at the air-water interface (AWI), and column studies with F-70 Ottawa sand at 100 % and ca. 50 % water saturation to explore transport mechanisms. Employed PFAS solutions encompass individual solutes and binary mixtures of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at concentration levels spanning four orders of magnitude to assess competitive and nonlinear sorption at the AWI. Observations demonstrate that concentration levels and competitive effects substantially influence PFAS transport in unsaturated systems. In the presence of PFOS, PFOA experienced less retention than would be anticipated based on single-solute behavior, and effluent breakthrough curves exhibited chromatographic peaking. The presented mathematical model for simultaneous flow and transport of PFAS was able to capture experimental observations with a consistent set of parameters and minimal curve fitting. These results demonstrate the robustness of the model formulation that included rate-limited interfacial mass transfer, an extended Langmuir-Szyszkowski model for adsorption at the AWI, and a scaled Leverett thermodynamic model to predict the AWI specific area. Overall, the results of this work underscore the importance of the AWI in PFAS transport and highlight the relevance of competition effects in adsorption formulations. [Display omitted] [ABSTRACT FROM AUTHOR]

Spectral Induced Polarization (SIP) has been suggested as a non‐invasive monitoring proxy for microbial processes. Under natural conditions, however, multiple and often coupled polarization processes co‐occur, impeding the interpretation of SIP signals. In this study, we analyze the sensitivity of SIP to microbially‐driven reactions under quasi‐natural conditions. We conducted flow‐through experiments in columns equipped with SIP electrodes and filled with natural calcareous, organic‐carbon‐rich aquifer sediment, in which heterotrophic denitrification was bio‐stimulated. Our results show that, even in the presence of parallel polarization processes in a natural sediment under field‐relevant geochemical conditions, SIP is sufficiently sensitive to microbially‐driven changes in electrical charge storage. Denitrification yielded an increase in imaginary conductivity of up to 3.1 μScm−1 ${\upmu }\mathrm{S}\,{\mathrm{c}\mathrm{m}}^{-1}$ (+140%) and the formation of a distinct peak between 1 and 10 Hz, that matched the timing of expected microbial activity predicted by a reactive transport model fitted to solute concentrations. A Cole‐Cole decomposition allowed separating the polarization contribution of microbial activity from that of cation exchange, thereby helping to locate microbial hotspots without the need for (bio)geochemical data to constrain the Cole‐Cole parameters. Our approach opens new avenues for the application of SIP as a rapid method to monitor a system's reactivity in situ. While in preceding studies the SIP signals of microbial activity in natural sediments were influenced by mineral precipitation/dissolution reactions, the imaginary conductivity changes measured in the biostimulation experiments presented here were dominated by changes in the polarization of the bacterial cells rather than a reaction‐induced alteration of the abiotic matrix. Plain Language Summary: To better predict the contribution of microbes to groundwater clean‐up it is important to locate microbes in the ground that are actively removing contaminants and measure how fast they are doing so. Our ability to do so, however, is limited by the difficulty in visualizing underground processes. Electrical methods such as spectral induced polarization (SIP) have been applied to monitor microbes and provide an alternative to visualize them underground. SIP, however, has so far only been shown to work in controlled environments and its sensitivity in natural systems remains a question. In this study, we conducted experiments with sediment collected from an underground aquifer, in which we stimulated microbial activity through the addition of nitrate, a widespread groundwater contaminant. Our results show that microbial consumption of nitrate causes a distinct SIP signal that is similar to SIP signals of bacteria in previously studied well‐controlled systems. Furthermore, we propose an approach to separate the SIP signal of microbes from that of other processes that occur in natural groundwater. This enables us to quickly asses where the microbes are active and can potentially improve future experiments through the localization of microbial hot‐spots and SIP‐guided sampling for more detailed microbiological analysis. Key Points: Microbial denitrification in natural sediments can be tracked using spectral induced polarization (SIP)σ″ ${\sigma }^{{\prime\prime}}$ spectra of a natural microbial community match reported spectra from single strains and the level of microbial activity affects σ″ ${\sigma }^{{\prime\prime}}$Superimposing Cole‐Cole terms provides a framework for separating microbial and abiotic contributions from SIP signals [ABSTRACT FROM AUTHOR]

In this study, a poly (methacrylic acid-co-ethylene dimethacrylate (poly(MAA-co-EDMA)) monolith was prepared for the selective adsorption of acidic dye, namely, methylene blue (MB), from wastewater. The fabrication of the monolith was carried out via photoinitiation polymerization by irradiating a mixture of methacrylic acid (MAA), ethylene dimethacrylate (EDMA), porogenic solvents and an initiator. Batch adsorption assays were performed to examine the impact of monolithic dosage and initial dye concentration on the adsorption capacity and efficiency of the monolith towards MB dye molecules. This adsorption kinetic study revealed that MB adsorption on the monolith followed a pseudo-second-order model and equilibrium adsorption behavior was best modeled with the Langmuir adsorption isotherm, which indicated monolayer adsorption with a maximum adsorption capacity of 50.00 mg g-1. Owing to the presence of negative binding sites on the monolithic surface, cationic MB molecules were selectively adsorbed in the MB/methyl orange (MO) mixture with an adsorption efficiency of 99.54% at equilibrium. Moreover, the MB-adsorbed monolith was regenerated up to four cycles, and the percentage removal efficiency of MB on the monolith dropped to 67.64 % after the fourth cycle. Finally, the monolith effectively adsorbed MB from the tap water in the presence of competing ions, and the maximum adsorptive capacity obtained was 47.62 mg g-1 with 84.5% adsorption efficiency. Hence, the poly(MAA-co-EDMA) monolith was found to be an adequate sorbent for the treatment of cationic dyes in the presence of other dyes and competing ions from wastewater. [ABSTRACT FROM AUTHOR]

The United States Environmental Protection Agency categorized polycyclic aromatic hydrocarbons (PAHs) as hazardous to humans upon acute and/or chronic exposure. This study investigated the simultaneous adsorption of several PAHs onto graphene wool (GW), thereby providing holistic insights into the competitive adsorption of PAHs onto graphene-based materials. SEM, TEM and FTIR provided evidence for the adsorption of PAHs and successful regeneration of the adsorbent accompanied by distinct morphological changes. Isotherm experiments revealed that adsorption of PAHs was significantly influenced by hydrophobic interactions between the sorbate and hydrophobic surface of GW. The Freundlich multilayer isotherm model best fit the experimental data obtained for both multi-component PAH and single-solute experiments as indicated by the Error Sum of Squares (SSE) obtained from nonlinear regression analysis. Experiments revealed that competitive adsorption had a limiting effect on the overall adsorption capacity as qmax and Kd were higher in single-solute than multi-component PAH experiments. The results suggest that partition distribution coefficients (Kd) between the solid–liquid interphase played a significant role in the overall adsorption and a positive correlation between Kd and LogKow of PAHs was established in single-solute experiments. Sorption-desorption experiments revealed that PAHs were adsorbed with a maximum removal efficiency of 100% at an optimum GW dosage of 2 g/L. Adsorption thermodynamics revealed that PAH adsorption onto GW is spontaneous and endothermic. The adsorbent was regenerated and reused for up to six times and its efficiency remained fairly constant. [ABSTRACT FROM AUTHOR]

• Novel FRA setup for water adsorption including response of surface temperature. • FRA method extended to determine thermal conductivity of the coating. • Adsorption dynamics governed only by thermal conductivity and micro mass transport. • Aluminum fumarate coating thermal conductivity independent of loading and temperature. • Alfum micro mass transport depends strongly on loading and temperature. The nonlinear sorption of hydrophobic organic contaminants (HOCs) could be changed to linear sorption by the suppression of coexisting solutes in natural system, resulting in the enhancement of mobility, bioavailability and risks of HOCs in the environment. In previous study, inspired from the competitive adsorption on activated carbon (AC), the displaceable fraction of HOCs sorption to soot by competitor was attributed to the adsorption on elemental carbon fraction of soot (EC-Soot), while the linear and nondisplaceable fraction was attributed to the partition in authigenic organic matter of soot (OM-Soot). In this study, however, we observed that the linear and nondisplaceable fraction of HOC (naphthalene) to a diesel soot (D-Soot) by competitor (phenanthrene or p -nitrophenol) should be attributed to not only the linear partition in OM-Soot, but also the residual linear adsorption on EC-Soot. We also observed that the competition on the surface of soot dominated by external surface was different from that of AC dominated by micropore surface, i.e., complete displacement of HOCs by p -nitrophenol could occur for the micropore surface of AC, but not for the external surface of soot. These observations were obtained through the separation of EC-Soot and OM-Soot from D-Soot with organic-solvent extraction and the sorption comparisons of D-Soot with an AC (ACF300) and a multiwalled carbon nanotube (MWCNT30). The obtained results would give new insights to the sorption mechanisms of HOCs by soot and help to assess their environmental risks. [Display omitted] [ABSTRACT FROM AUTHOR]

The sorption potentials of two soil colloids and fine powder kaolinite for Pb(II) and Cu(II) were analyzed, and the effects of pH, ionic strength and organic matter on the sorption were invetigated. The two soil colloids and fine powder kaolinite were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis. Black soil had more mineral compositions and surface functional groups. The sorption was pH-dependent. In the presence of humic acid, the adsorption of Pb(II) and Cu(II) ions on soil was increased, while the increase in ionic strengths decreased the adsorption. Sorption kinetics and isotherms of Pb(II) and Cu(II) onto three soil colloids were well fitted with Pseudo-second-order model and Langmuir model/Freundlich model. Black soil had the highest sorption capacity of Pb(II) (44.287 mg g−1) and Cu(II) (11.109 mg g−1), followed by red soil (9.764 and 4.152 mg g−1) and kaolinite (7.612 and 3.064 mg g−1 ). The two metals competed with each other during sorption.

A study of the competitive sorption of heavy metals onto sediments by means of a planned multifactorial experiment yielded equations describing the mutual influence of the zinc(II), cadmium(II), lead(II), and copper(II) cations in the sorption process, with the coefficients in the equations indicating the degrees of this influence. The competition between the metal ions significantly increases their mobility. Lead(II) and copper(II) cations prevent the binding of cadmium(II) and zinc(II) cations to sediments and promote their mobilization. Cadmium is a serious threat to aquatic ecosystems because of its mobility and high toxicity. After refinement under natural conditions the resulting mathematical models can be used for assessing and predicting the environmental risks of water pollution. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of the migration and competitive adsorption of methane and carbon dioxide in coal is crucial for the injection optimization design and injection displacement evaluation of the CO2 enhanced coalbed methane recovery (ECBM) project. In this paper, adsorption-desorption tests of three gaseous mixtures (75% CH4 + 25% CO2, 50% CH4 + 50% CO2, and 25% CH4 + 75% CO2) and pure CH4 and CO2 were performed on the anthracite from the southern Qinshui Basin. The results show that (1) there was an apparent hysteresis in sorption isotherms, and the size of hysteresis loops was related to the proportion of CO2 in the mixture. There was also a non-negligible error in using the extended Langmuir model to predict mixture sorption. (2) Separation factor (SCO2-CH4) for the sorption of CH4 and CO2 mixture varied with the equilibrium pressure and the equilibrium concentration of gas components. Its value was usually between 4 and 20. During the adsorption process, the SCO2-CH4 at low pressure was generally greater than that at high pressure. Moreover, SCO2-CH4 in the desorption process was generally higher than the adsorption process. (3) Bidisperse diffusion model could better describe the diffusion process of the mixture. In general, the macropore effective diffusivity varied as a power function with pressure. Under the same pressure, the macropore effective diffusivity increased with the increasing CO2 content. Further, the macropore effective diffusivity in the desorption process was larger than that in the adsorption process. The micropore effective diffusivity and the ratio of macropore uptake to micropore uptake had no apparent relationship with the gas component concentration and pressure. The results will help to comprehensively understand the sorption processes of the CH4 and CO2 mixture and provide basic numerical simulation data for the CO2-ECBM project in the southern Qinshui Basin. [ABSTRACT FROM AUTHOR]

• Sorption density of PO 4 -P on GAC and biochars is improved after pDADMAC coating. • Polymer coverage was confirmed by imaging and spectroscopic analyses. • Sorption mechanism on pDADMAC-coated and reference Mg-doped biochars was elucidated. • Sorption was partly inhibited by sulfate, carbonate, and manure extracts. • Sorption was more reversible with pDADMAC-coated than Mg-doped biochars. This study reports on the development of modified pyrogenic carbonaceous materials (PCMs) for recovering orthophosphate (PO 4 -P). The PCMs include softwood and hardwood biochars and a commercial granular activated carbon (GAC) that were modified by irreversible adsorption of the quaternary ammonium polymer, poly(diallyldimethylammonium) chloride (pDADMAC), which reverses electrokinetic charge and increases PO 4 -P sorption. MgO-doped biochars were prepared by a literature method for comparison. Imaging and spectroscopic analyses characterize pDADMAC coverage, MgO doping, and binding of PO 4 -P. At environmentally relevant concentrations, PO 4 -P sorption by the pDADMAC-treated biochars was ~100 times greater than that of the corresponding unmodified biochars, and was comparable to that of the corresponding MgO-doped biochars on a coating content basis. The pDADMAC-coated carbons bind PO 4 -P by ion exchange, while the MgO-doped biochars bind PO 4 -P principally by forming an amorphous Mg phosphate species. Susceptibility to competition from other relevant anions (Cl−, NO 3 −, HCO 3 −/CO 3 2−, SO 4 2−) and poultry and dairy manure extracts was moderate and comparable for the two types of modified softwood biochars. Sorption to the pDADMAC-treated biochars appears to be more reversible than to the MgO-doped biochars using stepwise water extraction. Greater reversibility may be advantageous for trapping and recycling phosphate. [ABSTRACT FROM AUTHOR]

Competitive sorption and desorption of Cd2+, Pb2+, and Hg2+ onto riverbank and sediment samples of an area impacted by pyritic residue in a Southern Brazilian catchment were evaluated. Although these ions are considered poorly mobile, a new approach has been proposed to assess their behavior and associated risk. In this sense, factorial design and three-dimensional surface methodology are proposed to describe the competitive sorption behavior of the metal ion in the environmental matrix, as well as an innovative mobilization factor (MF) to describe the desorption rate from the integration of the normalized difference of sorption-desorption fluorescence peaks. Sorption was carried out with a central composite factorial design (23) to estimate simultaneous effects of independent variables. Three-dimensional surface analysis indicated increasing Cd2+ equilibrium concentration (Ceq) with Hg2+ and Pb2+ initial concentration (Ci), showing synergistic effect and low Cd2+ affinity to the solid phase. Statistical analysis presented C i Hg as a significant variable for cadmium and lead dynamics, although C i Pb was also significant for Hg2+ releasing to the liquid phase. After integrating the sorption and desorption fluorescence peaks, the MF for Cd2+, Pb2+, and Hg2+ was around 0.2, 0.5, and 0.1 in riverbank sediment, and 0.3, 0.9, and 0.1 in sediment, respectively. Hence, consistent ion mobilization along the river was observed, with Pb2+ mobilizing 9 and 6 times more than Hg2+ and Cd2+, respectively. The transport of ions such as Pb2+ and Hg2+, usually considered immobile, has indeed occurred, causing contamination through the watershed and increasing environmental risk. [ABSTRACT FROM AUTHOR]

Echinacea purpurea marc (EPM), a residual of echinacea herb after the extraction process, was used as a natural low-cost sorbent for competitive sorption of 152+154Eu(III), 60Co(II) and 134Cs(I) radionuclides. The EPM was ground to prepare it for use in the sorption process. The variables influencing the sorption process were assessed, including pH, contact time, concentrations of metal ions, and temperature. EPM was characterized by different analytical instruments such as FTIR, SEM, XRD, and DTA/TGA. pH 4.0 was selected as the ideal pH value for competitive sorption of the studied ions. Adsorption kinetics data found that the sorption followed a pseudo-second-order model. The adsorption isotherm data was significantly better suited by the Langmuir isotherms in the case of Eu(III) ions while following Freundlich in the case of Co(II) and Cs(I) ions. Positive ΔHo values confirm the endothermic character of metal ion sorption onto EPM. The loading efficiencies of Eu(III), Co(II), and Cs(I) ions in the EPM column were 66.67%, 9.59%, and 4.81%, respectively. The EPM is a cost-effective and efficient separation of Eu(III) ions more than Cs(I) and Co(II) ions. Therefore, in the future, it will be a starting point for the separation of trivalent elements of lanthanide ions. • Echinacea purpurea marc was used a natural and low-cost sorbent. • Echinacea purpurea marc effectively separated Eu(III) ions from wastewater. • The kinetic data of adsorption fit well with pseudo-second-order model. [ABSTRACT FROM AUTHOR]

While significant advancements have been made in the synthesis of microporous polymers for gas separations in the last two decades, little is known regarding structure–property relationships under industrially relevant conditions involving highly condensable gases such as H 2 S. Recent work on the mixed-gas transport in an amine-functionalized microporous PIM (PIM-NH 2) has demonstrated benefits of simultaneous plasticization resistance and competitive sorption for increased permselectivity in binary CO 2 /CH 4 mixtures. In this work, we elucidate the effects of analogous competitive sorption relationships through pure- and mixed-gas permeation in an amine-functional microporous poly(aryl ether) (PAE-NH 2) and provide comparisons with PIM-NH 2 and the corresponding nitrile-functional counterparts, PAE-CN and PIM-1. In binary mixed-gas tests, PAE-NH 2 show a 2.5- and 2.4-fold increase in CO 2 /CH 4 and CO 2 /N 2 mixed-gas permselectivities, respectively, compared to the pure-gas case. In 20/20/60 H 2 S/CO 2 /CH 4 mixtures, amine-functionalized derivatives retain increases in CO 2 /CH 4 selectivities compared to the nitrile-functional analogues. Additionally, PIM-NH 2 , PAE-CN, and PAE-NH 2 have excellent plasticization resistance in 50/50 CO 2 /CH 4 binary mixed-gas tests up to 26 atm. [Display omitted] • PIM-1, PAE-CN, and amine-functional (PIM-NH 2 , PAE-NH 2) polymers were measured in CO 2 /CH 4 , CO 2 /N 2 , H 2 S/CO 2 /CH 4 mixtures. • Competitive sorption was observed in all four materials, but effects were most apparent in the amine-functional membranes. • CO 2 - and H 2 S-based permselectivities increased from pure- to mixed-gas tests due to exclusion of N 2 /CH 4 from the polymer. • The amine-functional materials demonstrated excellent plasticization resistance up to 26 atm in a 50/50 CO 2 /CH 4 mixture. [ABSTRACT FROM AUTHOR]

The pH and soil/solution ratio are two parameters influence the sorption of heavy metals in the soil. Selectivity sequences of cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) in a single and competitive system under different soil/solution ratios (1:2, 1:5, 1:10, 1:25, 1:50, and 1:100) and initial pH (3, 4, 5, 6, 7, and 8) was tested in a calcareous soil. The results showed that heavy metals sorption decreased with increasing soil/solution ratio, while it increased with increasing pH, in all soil/solution ratios and under both single and competitive systems. The most common selectivity sequence calculated on the basis of the Freundlich distribution coefficient at different soil solution ratios and pHs was Cd > Ni > Zn > Cu in a single system, while in a competitive system, the selectivity sequence was Ni > Zn > Cu > Cd. It seems at high heavy metals addition, both sorption and precipitation of Cd, Cu, Ni, and Zn (only at low soil/solution ratio) control their concentration in soil under all pHs and both at low and high soil/solution ratios in single and competitive systems. It was revealed that competition between studied heavy metals for exchange sites reduced Cd sorption and thus the mobility of Cd in a multiple system is higher than a single system, posing a serious health risk. The results of this study may be used to evaluate the risks and develop tools to minimize the risks of heavy metals in soils polluted with multiple heavy metals. [ABSTRACT FROM AUTHOR]

Through the example of the sorption-coprecipitation data for microelements simulating the corrosion, activation, and fission products, the nature of the isotherms of sorption of cations (M) by natural humic acids (HAs) was discussed. The dependence of the microelement distribution coefficient (Kd) on the ratio of the mass to volume of the HA solution in the 10–990 mg/L concentration range was associated with the occurrence of two parallel processes in the sorption system: competitive sorption of the M and Ca(II) ions by the HA precipitate and the formation of nonsorbable (Kd < 10 mL/g) complex of the M ion with high-molecular-weight organic compounds remaining in solution after HA precipitation. Optical spectroscopic data for the HA solutions and solutions above the solid HA precipitate revealed the presence of high-molecular-weight organic compounds in solution, as indicated by a maximum at 220 ± 20 nm and a shoulder at 264 ± 30 nm, characteristic for fulvic acids (FAs). A probable scheme of the interaction of the sorbate cations with the precipitate of HAs and their accompanying fulvic acid molecules was proposed. For the first time, removal of tritium (THO) from aqueous solutions by HA precipitates via isotope exchange reaction was reported. [ABSTRACT FROM AUTHOR]

The sorption potentials of two soil colloids and fine powder kaolinite for Pb(II) and Cu(II) were analyzed, and the effects of pH, ionic strength and organic matter on the sorption were invetigated. The two soil colloids and fine powder kaolinite were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis. Black soil had more mineral compositions and surface functional groups. The sorption was pH-dependent. In the presence of humic acid, the adsorption of Pb(II) and Cu(II) ions on soil was increased, while the increase in ionic strengths decreased the adsorption. Sorption kinetics and isotherms of Pb(II) and Cu(II) onto three soil colloids were well fitted with Pseudo-second-order model and Langmuir model/Freundlich model. Black soil had the highest sorption capacity of Pb(II) (44.287 mg g−1) and Cu(II) (11.109 mg g−1), followed by red soil (9.764 and 4.152 mg g−1) and kaolinite (7.612 and 3.064 mg g−1). The two metals competed with each other during sorption. [ABSTRACT FROM AUTHOR]

A high-fidelity physics-based model of mixed-gas transport coupled with kinetic and equilibrium adsorption is derived, and experiments were performed in order to calibrate and exercise the model. In the literature, a continuum-scale model that couples Fickian diffusion with Henry's law absorption, and kinetic Langmuir adsorption was previously developed to describe the diffusion and sorption of moisture in porous materials. Here, we expand the model to gases, rather than moisture, derive, and implement a competitive adsorption mechanism into the model to enable mixed-gas sorption. This model facilitates a mechanistic-based understanding of the sorption and diffusion processes of mixed gases in polymeric materials. Diffusion and sorption experiments were conducted for a range of partial pressures; model validation and calibration were carried out by comparing modeled mass uptake and experimental data considering the uncertainties of conceptualized (or assumed) physical processes and system parameters. Uncertainty quantification and sensitivity analysis methods are described and exercised here to demonstrate the capability of this predictive model. [ABSTRACT FROM AUTHOR]

Antibiotic contaminants, which are generally present in bi-solute systems, can be competitively adsorbed onto clays. Single- and bi-solute sorptions of sulfadiazine (SDZ) and ciprofloxacin (CIP) onto montmorillonite and kaolinite were investigated at pH values of 5 and 8. Freundlich and Langmuir models were used and fit the experimental data well for single-solute sorption. The sorption isotherms were nonlinear (NF = 0.265–0.730), and the maximum sorption capacities (qmL) of the SDZ and CIP onto montmorillonite were higher than those onto kaolinite. The octanol–water distribution ratio (Dow), cation exchange capacity (CEC), Brunauer–Emmett–Teller (BET) surface area (ABET), pore size, point of zero charge (pHPZC), and basal spacing predominantly affected the Freundlich constant (KF) and qmL of SDZ0 and CIP+ at pH 5 more than SDZ− and CIP± at pH 8. For bi-solute sorption, the presence of CIP inhibited the SDZ sorption onto montmorillonite and kaolinite. Competitive sorption models such as Sheindorf–Rebhun–Sheintuch (SRS), Murali–Aylmore (M–A) and the modified extended Langmuir model (MELM) were used; of these, the MELM provided the best prediction with SDZ sorption onto montmorillonite at pH 8 and CIP onto kaolinite at pH 5 and 8 in SDZ/CIP system occurring synergistically, whereas others occurred antagonistically. The distribution coefficient (Kd) of the bi-solute sorption decreased with increasing pH in the order cationic > neutral > anionic for SDZ and cationic > zwitterionic > anionic for CIP, which resembled the Kd of single-solute sorption. Fourier transform infrared spectroscopy (FT-IR) spectra indicated that amine in SDZ and keto oxygen in CIP were responsible for the interactions with the montmorillonite and kaolinite. [ABSTRACT FROM AUTHOR]

CO 2 -CH 4 mixed-gas sorption and permeation properties of a ladder polymer (PIM-Trip-TB) were measured experimentally at 35 °C to interpret nonideal transport behavior of polymers of intrinsic microporosity (PIMs). Both CH 4 and CO 2 mixed-gas solubilities were lower than those in the pure-gas environment mainly due to competitive sorption. In the range of pressures tested, the CO 2 /CH 4 mixed-gas solubility selectivity of PIM-Trip-TB coincided on average with the value at infinite dilution, and at all pressures, it was higher than the pure-gas solubility selectivity. Because CO 2 diffusion coefficient was found insensitive to mixture effects, we inferred that the increased diffusion coefficient of CH 4 and the consequent loss of CO 2 /CH 4 permselectivity in mixture environment were correlated to CO 2 -induced alteration of the selective diffusion domains of PIM-Trip-TB. Similar effects were also found for PIM-1 by an analysis of pure- and mixed-gas experimental permeation and sorption data. The increase of CH 4 mixed-gas diffusion coefficients from the pure-gas values was more pronounced for both PIMs (PIM-Trip-TB and PIM-1) than for a conventional low-free volume polymer 6FDA-mPDA polyimide reported previously; this indicates that the high intrachain rigidity in PIMs cannot restrain unfavorable mixture effects on CO 2 /CH 4 diffusion and permeability selectivity. Image 1 • CO 2 -CH 4 mixed-gas solubility in PIM-Trip-TB deviates from pure-gas values. • CO 2 vs. CH 4 mixed-gas solubilities can be fitted linearly regardless of concentration. • Equimolar CO 2 /CH 4 solubility selectivity in mixture is higher than pure-gas one. • CO 2 alters polymer size sieving domains thus depressing mixed-gas permselectivity. • Intrachain rigidity does not limit CO 2 -induced plasticization during CO 2 -CH 4 separations. [ABSTRACT FROM AUTHOR]

Bog iron ores are known for their sorption properties regarding heavy metals. However, they have not been commonly used as sorbents of arsenic compounds. The aim of this study was to investigate As(III) and As(V) immobilization by bog iron. The tests included varying initial As concentrations (0.01-20 mM), and initial pH values (2-12), and also sorption experiments to evaluate the competition between both As(III) and As(V) and heavy metal cations. The results showed that As removal by bog iron ores depends on the oxidation state of As--the removal of As(V) is lower than the removal of As(III). Immobilization of As was the most effective at medium initial concentrations of As (0.25-1 mM) in a slightly acidic or neutral pH environment. Competitive sorption experiments revealed that the occurrence of several ions in the solution significantly affects the sorption effectiveness. The bonding strength of As with a bog iron ore surface was estimated on the basis of three-step desorption experiments. Desorption of As resulted in the extraction of less than 50% of adsorbed As(III) and As(V). This study shows that bog iron ores constitute an appropriate adsorption material for arsenic especially at concentration range 0.25-5 mM, pH 5-10 for As(III) and 0.25-0.5 mM, pH 2-5 for As(V). However, there are no simple correlations between mineralogy and sorption capacity. [ABSTRACT FROM AUTHOR]

The role of organic matter (OM) in antimonate (further denoted as Sb(OH) 6) mobility in soil is unclear. The objective of this study was to evaluate Sb(OH) 6 –OM interaction. Antimonate solid:liquid distribution coefficients (K D) were measured at low Sb concentrations in soil samples with a natural gradient in soil organic carbon (OC) that were collected from different depths of up to 3 m in two excavated soil profiles and in a subset of four soil samples with experimentally increased OM concentration from addition of Suwannee River OM. The K D values were related to soil properties by multiple linear regression and described with the CD–MUSIC model of ferrihydrite. The K D values ranged from 12 to 2800 L kg−1 and decreased strongly with increasing OC concentrations, when normalized to the amount of iron (Fe) and aluminium (Al) in acid oxalate extracts (r = −0.69; p < 0.0001). Experimentally increasing OC by ∼1.5 g kg−1 increased soluble Sb and decreased Sb(OH) 6 K D values by up to a factor of 8. The multiple regression model reveals that sorption of Sb(OH) 6 to Fe and Al hydroxides decreases with increasing pH and increasing dissolved organic carbon concentration. This effect could be explained with geochemical modelling by the competitive and electrostatic effects of adsorbed humic substances on Sb(OH) 6 surface complexation to the reactive surface sites of the Fe and Al hydroxides. Finally, both models could predict the in situ pore water Sb concentrations of unspiked samples, with a RMSE of 0.35 for the regression model and 0.43 for the geochemical model on the log 10 Sb concentrations. For these predictions, the 0.1 M Na 2 HPO 4 –extractable Sb concentration was measured and used to estimate the reversibly sorbed Sb pool. This study shows that increasing soil OM increases Sb(OH) 6 mobility at low soil Sb concentration, likely due to competitive sorption on Fe and Al hydroxides and a process based, geochemical model was calibrated to describe Sb(OH) 6 mobility in soil. • Soil organic matter increases antimonate mobility in agricultural soil • Organic matter decreases antimonate sorption to Fe an Al hydroxides by competition • Organic matter competition to antimonate can be described by geochemical modelling [ABSTRACT FROM AUTHOR]

Abstract Fundamental gas transport properties of a novel thermally rearranged polymer (TPBO) prepared from a co-polyimide precursor with controlled triptycene molar content are discussed. He, N 2 , CH 4 , CO 2 and C 2 H 6 sorption isotherms were experimentally measured in the range 5–50 °C and up to 32 atm and analyzed with the dual mode model. Water vapor sorption and diffusion at 35 °C was also investigated. TPBO exhibits larger gas and vapor sorption capacity relative to previously reported thermally rearranged polymers. The dual mode parameters retrieved from the analysis of single gas sorption isotherms were used to estimate a priori the sorption behavior in mixed gas conditions. The predicted mixed gas solubility-selectivity is significantly higher than ideal solubility-selectivity and it is comparable to that exhibited by other glassy polymers. Gas and vapor diffusion coefficients in TPBO were estimated from the solution-diffusion model and from sorption kinetics, respectively, and are larger than in previously reported thermally rearranged polymers. The dual sorption-mobility model indicates that the polymer rigidity significantly affects gas diffusion coefficients. CO 2 /CH 4 diffusivity-selectivity was larger than in other glassy polymers, pointing out the superior size-sieving ability provided by triptycene units. Water vapor sorption experiments revealed that TPBO is more hydrophilic relative to previously reported thermally rearranged polymers: theoretical models were exploited to speculate water vapor distribution in the polymer matrix. Graphical abstract fx1 Highlights • Gas solubility in TPBO is larger relative to other high performance polymers, except PIM-1. • TPBO exhibits larger diffusivity-selectivity relative to other polymers. • TPBO is more hydrophilic relative to previously reported TR polymers. • Polymer rigidity affects gas diffusion behavior. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemical activation of the mesoporous carbon was carried out under mild conditions. • Sequential activation promotes the development of carboxylic acids on the surface. • Fast kinetics and high sorption capacities of metals (Co, Ni and Mn) were achieved. • Selectivity adsorption to divalent cations was risen with the chemical activation. • Sulfuric acid was effectively used to recover and preconcentrate the sorbed metals. The competitive sorption of Co2+, Li+, Ni2+, and Mn2+, strategic metals from spent lithium-ion batteries and their leachates, was studied using activated mesoporous carbons. The mesoporous carbon was synthesized by the replica method using silica gel as a template and exhibited a high surface area with an accessible pore volume due to mesopores (V meso > 95%). Fast kinetics and high sorption capacities of these metals were achieved with the chemical activation of mesoporous carbons. The surface modification of the mesoporous carbon was carried out by physical activation with O 2 at 450 °C and chemical activation under mild conditions (room temperatures) with NaClO 2 /H 2 O 2 as oxidizing agents. FTIR analysis and conductimetric titration showed that the combination of an initial physical activation step, followed by chemical functionalization, maximized the formation of carboxylic acids (from 0.2 to 0.9 meq/g), due to the complete oxidation of the weakly acidic groups. Those carbons were tested in sorption experiments of the lithium-ion battery metals in monometallic solutions, where physically activated and chemically reactivated mesoporous carbon selectively removed over 80% of Co2+, Ni2+, and Mn2+, with sorption capacities over 20 mg/g, while only 20% of Li+ was removed. This carbon stood out amongst the others studied (2 to 11-fold increase in sorption capacities depending on the metal) and was tested in multimetallic solutions, showing fast removal rates, reaching equilibrium within the first 15 min, as well as selectivity towards divalent cations (18 mg/g of Co2+) with insignificant lithium sorption (q Li = 0.33 mg/g). Desorption of metals was carried out using H 2 SO 4 , which allowed the recovery and twofold of the initial concentrations of Co, Ni, and Mn. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Effects of biochar on sorption of antibiotics in pig manure were investigated. • Biochar increased sorption heterogeneity for sulfamethazine and florfenicol. • Better sorption capacities of plant-derived biochar than biosolids-derived biochar. • Sorption of florfenicol and sulfamethazine enhanced, but of oxytetracycline reduced. • Biochar retards otherwise less sorbed antibiotics in manure. Abstract Using manure contaminated with antibiotics as fertilizer is a primary source of soil pollution with antibiotics and concomitantly with antibiotic resistance genes (ARG). Bioavailable antibiotics trigger further ARG amplification during manure storage. Consequently it is aimed to facilitate the immobilization of antibiotics in manure. To this end, five biochars derived from pine cone (BCP), rice husk, sewage sludge, digestate and Miscanthus were tested as additional sorbents in liquid pig manure for sulfamethazine, ciprofloxacin, oxytetracycline and florfenicol. Non-linear sorption was best-fit using the Freundlich isotherm (R 2 > 0.82) and the pseudo-second-order model best described sorption kinetics (R 2 > 0.94). Antibiotics' sorption onto manure increased in the order sulfamethazine < florfenicol < ciprofloxacin < oxytetracycline. Admixtures of BCP to manure changed the order to sulfamethazine < oxytetracycline < florfenicol = ciprofloxacin. Generally, with the addition of biochar, sorption coefficients of florfenicol increased most (by factors>2.7) followed by sulfamethazine and ciprofloxacin. Yet, oxytetracycline was mostly mobilized probably due to competitive adsorption. Effects depended on the proportion of biochar added and the type of biochar, whereby plant-derived biochar exhibited better immobilization of antibiotics. Depending on the type and portion of biochar, admixtures to manure can be used to lower the mobility and hence bioavailability of fenicols, fluoroquinolones and sulfonamides. [ABSTRACT FROM AUTHOR]

Abstract The scavenging properties of MnO 2 are largely attributed to sorption on layer vacancy sites. However, co-occurrence of Mn(II, III) with MnO 2 can change mineral reactivity by modifying its Mn(III) content or number of free vacancy sites. These processes are critical in biogenic MnO 2 because nascent precipitates are in contact with aqueous Mn(II) and redox processes involving the biomass can modify the Mn(III) content of the oxide. Here we studied the mechanism of Zn(II) and Pb(II) sorption by the biogenic MnO 2 precipitated by Pseudomonas putida GB-1. Sorption isotherms on biogenic MnO 2 at pH 5.2 ± 0.3 showed considerably higher loadings for Pb(II) (0.49 mol Pb mol−1 Mn) than for Zn(II) (0.12 mol Zn mol−1 Mn). For loadings above 0.1 mol mol−1 Mn, Zn(II) and Pb(II) sorption was concomitant, albeit to different extents, with Mn(II) accumulation in solution. Wet chemical measurements and analysis of Zn K–edge and Pb L 3 -edge EXAFS spectra showed that the difference in metal loadings on the oxide and extent of Mn(II) release to solution originates from the ability of the cations to displace interlayer Mn(III), which then undergoes disproportionation and accumulates as Mn(II) in solution. In addition, the formation of nanoscale precipitates rich in Pb-P-Cl in the biomass matrix, as shown by energy dispersive X-ray analysis, leads to greater accumulation of Pb than Zn on the biomass. Our findings show how the reactivity of biogenic MnO 2 towards co-occurring trace or contaminant metals in natural systems depends directly on the mineral Mn(III) content and competitive sorption processes. Highlights • Metal sorption by biogenic MnO 2 was studied using EXAFS spectroscopy and STEM-EDX imaging. • Zn partitions to biomass and MnO 2 at all loadings at pH 5. • Pb can access four times as many reactive sites compared to Zn. • Pb but not Zn can dislodge Mn(III) adsorbed on vacancy sites. • Initial Mn(III) content and competitive sorption control contaminant uptake by biogenic MnO 2. [ABSTRACT FROM AUTHOR]

Abstract In the context of geological disposal of radioactive waste, one of the controlling mechanisms for radionuclide migration through subsurface strata is sorption to mobile colloidal bentonite particles. Such particles may erode from the repository backfill or bentonite buffer and yield measurable (0.01–0.1 g/L) concentrations in natural groundwater. The extent of sorption is influenced by colloid concentration, ionic strength, radionuclide concentration, and the presence of competing metals. Uranium (VI) and cesium sorption to bentonite colloids was investigated both separately and together in low ionic strength (2.20 mM) artificial rainwater (ARW) and high ionic strength (169 mM) artificial groundwater (AGW; representative of a fractured carbonate rock aquitard). Sorption experiments were conducted as a factor of colloid concentration, initial metal concentration and opposing metal presence. It was shown that both U(VI) and Cs sorption were significantly reduced in AGW in comparison to ARW. Additionally, the sorption coefficient K d of both metals was found to decrease with increasing colloid concentration. Competitive sorption experiments indicated that at high colloid concentration (1–2 g/L), Cs sorption was reduced in the presence of U(VI), and at low colloid concentration (0.01–0.5 g/L), both Cs and U(VI) K d s were reduced when they were present together due to competition for similar sorption sites. The results from this study imply that in brackish carbonate rock aquifers, typical of the Israeli northern Negev Desert, both U(VI) and Cs are more likely to be mobile as dissolved species rather than as colloid-associated solids. Graphical abstract Unlabelled Image Highlights • Batch experiments determined sorption of U(VI) and Cs under environmental conditions. • Experiments show sorption in high salinity groundwater and low salinity rainwater. • K d for both elements increased with decreasing colloid concentration. • Presence of U(VI) reduced Cs sorption to bentonite surfaces, and vice versa. • Transport models should account for colloid concentration and competitive sorption. [ABSTRACT FROM AUTHOR]

Abstract The present study focuses on the phosphate uptake by synthetic ZnAl-layered double hydroxides having different charge density due to the modification of the cationic ratio (Zn2+/Al3+) within the brucite-like sheets. The structure of the as-synthesized ZnAl-LDH was confirmed by X-ray diffraction and 27Al NMR and micro-Raman spectroscopy characterization techniques. The materials were applied for sorption of phosphate anions in aqueous media under relevant conditions. Parameters affecting the sorption process were thoroughly investigated, such as the layer cationic ratio, the exchangeable interlayer anion, thermal treatment and competitive sorption in the presence of co-existing anions. The sorption data provided information regarding the relationship between the phosphate uptake and the physical-chemical properties of these materials. The phosphate adsorption onto the non-calcined LDH occurred via the anionic exchange mechanism while both structural reconstruction and precipitation mechanisms were observed for the calcined materials. The obtained results suggest that the Zn containing LDH are suitable candidates for the phosphate recovery or removal from aqueous media in wastewater treatment processes. Graphical abstract Unlabelled Image Highlights • Different ZnAl-LDH were synthesized by structural modification of the Zn/Al cationic ratio and various interlayer anions • The ZnAl-LDH show high selectivity and high adsorption capacity for phosphate anions • Combined micro-Raman and 27Al-NMR spectroscopic investigation show the presence of Al-enriched domains at high Al content • Modeling of kinetics and asorption isotherms show different mechanism of phosphate uptake by ZnAl-LDH or calcined products • The ZnAl-LDH are suitable candidates for the phosphate recovery or removal from aqueous media [ABSTRACT FROM AUTHOR]

Abstract Soil is a heterogeneous porous media that is comprised of a variety of organo-mineral aggregates. Sorption of heavy metals onto these composite solids is a key process that controls heavy metal mobility and fate in the natural environment. Pollution from a combination of heavy metals is common in soil, therefore, understanding the competitive binding behavior of metal ions to organo-mineral composites is important in order to predict metal mobility and fate. In this study, batch experiments were paired with spectroscopic studies to probe the sorption characteristics of ternary Cd Ni Cu sorbates to a binary organo-goethite composite made with Bacillus cereus cells. Scanning electron microscopy shows that goethite nano-sized crystals are closely associated with the bacterial surfaces. Sorption experiments show a larger adsorptivity and affinity for Cu than Cd/Ni on goethite and B. cereus, and the goethite– B. cereus composite. X-ray photoelectron spectroscopy reveals that carboxylate and phosphate functional moieties present on the bacterial cell walls are primarily responsible for metal sorption to the goethite– B. cereus composite. Synchrotron-based X-ray fluorescence shows that Cu and Ni are predominately associated with the bacterial fraction of the goethite– B. cereus composite, whereas Cd is mainly associated with the goethite fraction. The findings of this research have important implications for predicting the mobility and fate of heavy metals in soil multi-component systems. Graphical abstract Image 1 Highlights • Larger adsorptivity & affinity for Cu than Cd and Ni on goethite-bacteria composite. • Competitive sorption among Cu, Cd and Ni is weaker on composite than on goethite. • Cu and Ni are mainly bound to the bacterial fraction of the binary composite. • Cd is sorbed mainly on the goethite fraction of the binary composite. Cd, Ni and Cu ions compete for similar binding sites on the end-member goethite and B. cereus , but due to different binding affinities, Cu and Ni are mainly bound to the bacterial fraction whereas Cd is predominately sorbed on the goethite fraction of the binary bacteria–mineral composite. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the competitive sorption of black soil to adsorb Pb(II) and methylene blue (MB) from multi-contaminated soils. According to the experimental data, the process of adsorption can be clearly explained by pseudo-second-order kinetic equation. Both single and binary systems of the adsorption isotherms had a good fit with Langmuir models. The maximal adsorption abilities of Pb(II) and MB acquired from binary systems sorption were attenuated compared to those from the single system (Pb(II): 77.70 > 65.96 mg g−1; MB: 242.31 > 222.36 mg g−1). Pb(II) and MB can inhibit each other's sorption ability. A combination of three-dimensional excitation-emission matrix (3D-EEM), synchronous fluorescence spectra as well as two-dimensional correlation spectroscopy (2D-COS) were employed to determine the binding of dissolved organic matter (DOM) for Pb(II) and MB during soil sorption process. As a result, 3D-EEM implicated that the two main composes of DOM were humic acid-like substances and the fluorescence of DOM specimens were gradually diminished with increasing concentrations of Pb(II) and MB. According to synchronous fluorescence spectra, static quenching of Pb(II) and MB mainly led to fluorescence quenching. Specifically, fluorescence-2D-COS implicated that Pb(II) and MB bound to fluorescence in the following sequence: the earlier occurrence of the humic-like fraction compared to that of protein-like fraction. FTIR-2D-COS results concluded that the structural change sequence of DOM by Pb(II) binding followed the order: 1700＞863＞1332＞1529＞1200＞1086 cm−1 and the sequence of the MB binding affinities followed the order: 1520＞1399＞1345＞1152＞1602＞993＞881 cm−1. These findings would be beneficial to understand the mechanism of adsorb multi-component systems and have the potential to contribute significance to the interaction mechanism of multi-component with soil DOM at the molecular level. Graphical abstract fx1 Highlights • Investigated competitive sorption for multi-components onto black soil. • Interaction between soil-derived DOM and contaminants were studied by fluorescence spectrum and FTIR. • Pb(II) and MB binding to DOM were both in the order: humic-like fraction > protein-like fraction. • Calculated the Pb(II) and MB binding affinities followed the sequential orders from FTIR-2D-COS. [ABSTRACT FROM AUTHOR]

The competitive sorption of the antibiotics sulfamethoxazole (SMX) and trimethoprim (TMP) and SMX-Cd(II) on a hybrid clay nanosorbent (NanoSorb) was investigated in detail in this work. NanoSorb was synthesized by sorbing a surfactant on bentonite. Besides, the sorption of SMX on the NanoSorb was confirmed by FTIR analysis, and SMX was mainly sorbed on NanoSorb by a partition mechanism due to hydrophobic interactions. Otherwise, the single adsorption of Cd(II) and TMP onto NanoSorb were due to electrostatic interaction and hydrophobic partition, respectively. The capacity of NanoSorb for sorbing single SMX was very similar to that for single Cd(II), but more than 10 times higher than that for single TMP. The competitive sorption of SMX-TMP was antagonistic because the sorption of one antibiotic on NanoSorb was decreased by the presence of the other antibiotic. The uptake of SMX was reduced up to 43.4% by the presence of TMP, whereas the presence of SMX decreased the uptake of TMP up to 29.6%. The non-modified Langmuir multicomponent isotherm (NLMI) interpreted quite well the experimental competitive sorption data of SMX-TMP. On the other hand, the competitive sorption of SMX-Cd(II) on NanoSorb revealed that the sorption of SMX was non-interactive because it was not influenced by the presence of Cd(II). Whereas, the sorption of Cd(II) was synergistic or cooperative since the uptake of Cd(II) sorbed increased considerably with the uptake of SMX sorbed on NanoSorb. The two-site Langmuir model fitted the experimental competitive sorption data of Cd(II) on NanoSorb saturated with SMX. The application of this isotherm was based on the fact that Cd(II) sorbed on two types of sites: a) cationic sites of the NanoSorb and b) Pi-cation interactions between the aromatic ring of the SMX sorbed on NanoSorb and Cd 2+ . [ABSTRACT FROM AUTHOR]

In order to develop promising sorbents for value-added application of solid wastes, low-cost aluminum-enriched biochar was prepared from abandoned Tetra Pak used to hold milks, a paper-polyethylence-Al foil laminated package box, after acid pretreatment and subsequent slow pyrolysis under an oxygen-limited environment at 600 °C. The basic physicochemical properties of the resultant biochar were characterized and the sorption performance of aqueous As(III) and As(V) was investigated via batch and column sorption experiments. Carbon (49.1%), Ca (7.41%) and Al (13.5%) were the most abundant elements in the resultant biochar; and the specific surface area and the pH value at the point of zero charge (pHPZC) were 174 m 2  g −1 and 9.3, respectively. Batch sorption showed excellent sorption performance for both As(III) (24.2 mg g −1 ) and As(V) (33.2 mg g −1 ) and experimental data were fitted well with Langmuir model for the sorption isotherms and pseudo-second order kinetic model for the sorption kinetics. The residual concentrations of As(V) after sorption were below the limited value of arsenic in WHO Guidelines for Drinking water Quality (0.01 mg L −1 ) even if coexistence of PO 4 3− . Column sorption confirmed the high sorption performance for As(III) and As(V). So the slow pyrolysis of abandoned Tetra Paks as low-cost and value-added sorbents is a sustainable strategy for solid waste disposal and wastewater treatment. [ABSTRACT FROM AUTHOR]

This study aims to investigate the single and binary biosorption of Cr(III) and Ni(II) by pine bark chemically treated with NaOH solution (MPB). The studies involved the effect of initial pH in the equilibrium, as well as kinetic uptake using synthetic solutions. Equilibrium tests were also conducted with an industrial effluent. The kinetic model of pseudo-second order described well the data of single and binary systems. The equilibrium data were better described by the Langmuir model for both metals. The maximum adsorption capacity (qmax) to single system was 31.4 and 23.7 mg/g for Cr(III) and Ni(II), respectively. To analyse the competitive sorption between chromium and nickel ions, the modified Langmuir and Freundlich models were tested for two different concentration (mEq/L) ratios Cr(III)/Ni(II) of 1:1 and 2:1. The modified Langmuir model is also the best to fit the experimental data for both syntetic and industrial effluents. In the synthetic effluent, the qmax value for Cr(III) in MPB was about 25 mg/g, while qmax for Ni(II) decreased from 12.4 to 5.5 mg/g. The results showed that Ni(II) did not significantly interfere in Cr(III) adsorption capacity, whereas Cr(III) decreased the uptake of Ni(II). The industrial effluent contains several species, and thus, the sorption capacities for Cr(III) and Ni(II) were significantly affected. [ABSTRACT FROM AUTHOR]

Pollution of water by single antibiotics has been investigated in depth. However, in reality, a wide range of different contaminants is often mixed in the aquatic environment (contaminant cocktail). Here, single and competitive sorption dynamics of ionizable norfloxacin (NOR), sulfamerazine (SMR) and oxytetracycline (OTC) by both pristine and modified biochars were investigated. Sorption kinetics of the three antibiotics was faster in ternary-solute than single-solute system. Sorption efficiency was enhanced in the competitive system for NOR by the pristine biochar, and for OTC by both the pristine biochar and the modified biochar, while SMR sorption by the pristine biochar and the KOH-modified biochar was inhibited. Sorption was governed by electrostatic interactions, π-π EDA and H-bonds for antibiotics sorption by biochar. SMR and OTC sorption by biochar was influenced by cation bridging and surface complexation, respectively. This research finding will guide the development of treatment procedures for water polluted by multiple antibiotics. [ABSTRACT FROM AUTHOR]

This study examined the sorption performance of synthesized nanosized zeolite for the elimination of Cs+ and Sr2+ cations in a binary metal system. The influence of pH, sorbent amount, temperature, and contact time was studied. The relationship between each of these parameters and the removal efficiency was investigated. An analysis of the rate data was performed using both pseudo-first- and second-order reaction models. The ranking of three equilibrium sorption isotherm models used (Redlich-Peterson, Langmuir, and Freundlich) with a variety of numbers of parameters was determined using the corrected Akaike’s information criterion. The results demonstrate that a pseudo-second-order model fits the sorption kinetic data better than a pseudo-first-order model. The isotherm model rank order that best described the data statistically was Redlich-Peterson > Langmuir > Freundlich for the cesium ions and Langmuir > Redlich-Peterson > Freundlich for the strontium ions. Our results revealed that the existence of Sr2+ caused a significant reduction of Cs+ sorption in the binary metal mixture according to a lumped parameter model and vice versa. The results show that the synthesized material’s surface had a relatively stronger affinity for Cs+ than for Sr2+. [ABSTRACT FROM AUTHOR]

Phenolic acids play an important role in the formation of soil profiles, however their cooperative sorption by mineral phases under environmentally relevant concentrations is poorly studied. In the present work the sorption of an equimolar mixture of phenolic acids by kaolinite modified with amorphous aluminum hydroxide has been studied under both batch and continuous-flow conditions. It has been found that the sorption of gallic and protocatechuic acids containing OH groups in the ortho position exceeds the sorption of p-hydroxybenzoic and methoxylated acids (vanillic, syringic, and ferulic) by an order of magnitude. The study of sorption under dynamic (continuous-flow) conditions has shown the competition of acids for binding sites, while the active centers of kaolinite-Al(OH)x are being occupied. The sorbed gallic acid displaces the other acids, which pass into solution in the following order: p-hydroxybenzoic acid > vanillic acid > syringic acid ≫ ferulic acid > protocatechuic acid. The revealed regularities indicate potentially important role of ortho-substituted hydroxybenzoic acids in the formation of soil organic matter, while p-hydroxybenzoic, vanillic, and syringic acids can be more important for the composition of soil solutions and natural waters. [ABSTRACT FROM AUTHOR]

kinetic model of the mass transfer of a microcomponent in the simplest competitive system from the sorbed state (A) into a solution (B) and then into a sorbent (C) in accordance with the scheme A ⇄ B ⇄ C was formulated within the framework of competitive sorption statics. The kinetic equations were solved numerically. The influence exerted by the weight of competing sorbents А and С and by the degree of reversibility of linear reactions on the nonequilibrium decontamination factor Kdec(t) was determined. The time in which the equilibrium decontamination factor is attained for the model of chemical sorption kinetics was estimated from the experimental data on the rate constants of direct and reverse heterogeneous reactions and on the distribution coefficients of Cs(I) in the SiO2 (A)-CsCl solution (B)-Prussian Blue (C) system. [ABSTRACT FROM AUTHOR]