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[Display omitted] • Titanium white waste was used as the iron source to prepare LiFePO 4 cathode material. • The feasibility of whole process was verified by thermodynamic analysis. • The contents of impurities in the product were far below the standard. • The electrochemical performance of the synthesized LiFePO 4 was satisfactory. Large amounts of titanium white waste are generated in the production of titanium dioxide using sulphate method, which in turn can be used to prepare LiFePO 4 cathode material, thereby reducing environmental risks and achieving resource recovery. However, a key challenge lies in the elimination of impurities. In this work, a cost-efficient and straightforward approach based on phase transformation during hydrothermal treatment was proposed to utilize titanium white waste with calcium dihydrogen phosphate for the preparation of LiFePO 4 cathode material. The content of Fe in the leachate was enriched to 81.5 g/L after purification, while 99.9 % of Ti and 98.36 % of Al and were successfully removed. In the subsequent process for Fe/P mother liquor preparation, the losses of Fe and P were only 5.82 % and 2.81 %, respectively. The Fe and P contents of the synthesized FePO 4 product were 29.47 % and 17.08 %, respectively, and the Fe/P molar ratio was 0.986. Crystal phase of the product matched well with standard iron phosphate, and the lamellar microstructure of FePO 4 was uniform with the particle size ranging from 3 to 5 μm. Moreover, the contents of impurities in the product were far below the standard. The initial discharge of LiFePO 4 synthesized by the iron phosphate was 160.6 mAh.g−1 at 0.1C and maintained good reversible capacity after 100 cycles. This work may provide new strategy for preparing LiFePO 4 cathode material from industrial solid waste. [ABSTRACT FROM AUTHOR]

The recovery of iron phosphate from the leaching slag of used lithium iron phosphate cathode materials is a crucial step to achieve closed-loop recovery of lithium iron phosphate, which has not yet been effectively accomplished. In the study, ultrasonic-assisted sulfuric acid leaching was used to remove impurities in the iron phosphate, to meet the stringent impurity content requirements for battery-grade iron phosphate regarding impurity content. Optimization of leaching conditions involved a sulfuric acid concentration of 0.2 mol·L-1, acid-leaching time of 30 min, power of 50 W, and reaction temperature of 80°C. Under these conditions, the removal efficiencies of Cr, Cu, Ni, and Zn in iron phosphate were 26.09%, 83.0%, 75.9%, and 96.3%, respectively. Simultaneously, the content of impurity elements Cr and Zn concurred with the standard for battery-grade iron phosphate (HG/T 4701-2021), with both 50 ppm and 10 ppm contents. The leaching results indicated the effectiveness of ultrasound in enhancing the removal of impurity elements in iron phosphate within a sulfuric acid solution. Further analyses, including XRD, particle size, TEM, and XPS indicated that the surface of the iron phosphate particles cavitated after ultrasonic acid leaching, resulting in the formation of numerous pores. Additionally, particle collisions led to a reduction in particle size, with no generation of by-products during the process. This innovative approach not only contributed to the removal of impurity elements but also provided insights into the reuse of leaching slag (iron phosphate) and offered guidance for the recovery of metals from waste lithium iron phosphate cathode materials. [ABSTRACT FROM AUTHOR]

The precipitation method is an efficient, economically feasible, and reproducible synthetic route to cathode materials for lithium-ion batteries with attractive performance characteristics, in particular, lithium iron phosphate (LiFePO4). This paper reviews the mechanisms of the key steps of the synthesis, namely, precipitation of iron phosphate FePO4 followed by its sintering with a lithium-containing raw material to give the LiFePO4 phase. The most probable interactions determining the kinetics of the precipitation process are considered using the data on the dissociation degree of the reacting components. The influence of the nature and concentrations of the commonly used sources of iron (FeSO4, FeCl3, Fe(NO3)3) and phosphorus (H3PO4, NH4H2PO4, (NH4)2HPO4), as well as the precipitation conditions (pH, temperature) on the precipitation efficiency of FePO4 is analyzed. The effect of the nature of the lithium-containing raw material (LiOH, Li2CO3, LiNO3) and the sintering (calcination) temperature on the morphology, phase composition, and electrochemical properties of the resulting LiFePO4 is discussed. The possibility is considered of obtaining spherical particles with high bulk density, which provides high specific and volumetric energy density of electrochemical cells. Based on the relationships established, optimal parameters for the synthesis of LiFePO4 with preliminary FePO4 precipitation step are proposed. [ABSTRACT FROM AUTHOR]

In the current work, we report on the synthesizing of a series of novel nanocomposite materials obtained by functionalizing the SBA-15 silica matrix with anchored iron phosphonate molecules and the following thermal treatment. The obtained results reveal the formation of a unique amorphic layer of Fe-based compounds on the surface of silica walls of SBA-15 channels as a result of the organic groups' decomposition after moderate thermal treatment. Due to their unique structure, represented in an active Fe-containing amorphous coating spread over a large surface area, these materials are of great interest for their potential applications in fields such as catalysis, adsorption, and non-linear optics. The obtained materials remain amorphous, preserving the SBA-15 mesoporous structure up to temperatures of approximately 800 °C, after which the partial melting of the silica backbone is observed with the simultaneous formation of nanocrystals inside the newly-formed glassy mass. All obtained materials were characterized using such techniques as thermogravimetry, transmission and scanning electron microscopy combined with energy dispersive x-ray spectroscopy mapping, Raman spectroscopy, N2 sorption analysis, x-ray diffraction, x-ray photoelectron spectroscopy, Mössbauer spectroscopy, and SQUID measurements. [ABSTRACT FROM AUTHOR]

Iron phosphate@talc (IPT) sorbent was fabricated by precipitation method and utilized for 137Cs, 152+154Eu, and 131Ba sorption from aqueous media. Different analytical apparatuses such as XRD, FT-IR, SEM, and XRF were used to find the structure, morphology, and functional groups of IPT sorbent. Different parameters like shaking time, pH, temperature, and initial metal concentrations were studied. The obtained data reveal that the sorption of 137Cs, 152+154Eu, and 131Ba was pH, time-dependence, and kinetics following pseudo-2nd-order kinetics. The Langmuir and Freundlich equations were used as model isotherms. Thermodynamics parameters were calculated to prove that the sorption reaction was spontaneous and endothermic. [ABSTRACT FROM AUTHOR]

Battery grade iron phosphate was prepared through three processes of nitric acid dissolution, coprecipitation and calcination. In the first stage, iron phosphate slag was dissolved with strong oxidizing acid to obtain iron phosphate solution containing iron and phosphorus. In the second stage, the pH value of iron phosphate solution was adjusted by ammonia water to make the solution precipitate into iron phosphate. In the third stage, the final product anhydrous iron phosphate was obtained through calcination. The calcined products were evaluated by XRD, SEM, particle size distribution and molar ratio of iron to phosphorus. The process research shows that the best process conditions in the first stage are solid-liquid ratio 1∶12, nitric acid concentration 7.6 mol/L, dissolution time 5 h, dissolution temperature 90 ℃,under which the dissolution rate of ferrophosphorus slag is 96.39%. The optimum technological conditions in the second stage are the molar ratio of iron and phosphorus in the solution is 1∶1, the reaction temperature is 80 ℃, pH=1.0, time is 4 h, and the molar ratio of iron and phosphorus in the prepared FePO4 is 0.97. The optimum calcination temperature is 500 ℃,and qualified iron phosphate is prepared. [ABSTRACT FROM AUTHOR]

A highly organized hexagonal mesoporous iron phosphate framework structure with the designation HMI‐41 was successfully synthesized for the first‐time in a reproducible way using imidazolium‐based ionic liquid as structure directing agent. The unique templating properties of ionic liquid generated a highly ordered well‐crystallized mesoporous matrix having high surface area (445 m2 g−1), thicker pore wall (2.1 nm) and narrow pore size distribution (3.1 nm). The presence of active sites within a tetrahedral framework structure made the novel HMI‐41 catalyst highly effective for phenol hydroxylation in an acidic medium with hydrogen peroxide as the oxidant. The catalyst exhibited outstanding performance, achieving an impressive 80% hydroquinone selectivity and 21% phenol conversion with a hydroquinone‐to‐catechol ratio of seven, which is the highest value ever reported. [ABSTRACT FROM AUTHOR]

In view of the current situation wherein acid resources and valuable components in titanium dioxide waste acid cannot be effectively extracted and are prone to secondary pollution, our research team proposed a new technique consisting of step extraction and the comprehensive utilization of titanium dioxide waste acid. In this paper, the thermodynamics of selective precipitation and the preparation of doped iron phosphate from waste acid were studied. The thermodynamics results show that the content of Al3+, Mn2+, Mg2+, and Ca2+ in the reaction system can be tuned by adjusting the pH during the pre-precipitation process. In the first step, these impurity ions should be settled as much as possible; then, Fe2+ should be oxidized to Fe3+ so as to obtain iron phosphate with higher purity in the next step of the precipitation process. The effects of the reaction temperature, seed crystals, pH value, and P/M on the precipitation process were investigated in detail. The experimental results show that in the reduced state, the optimal precipitation conditions are a temperature of 75 °C, an initial pH value of 4.5, and an optimal P/M molar ratio of 1.1. In the oxidized state, the optimal precipitation conditions are a temperature of 60 °C, a solution pH = 2.5, and a reaction time of 25 min. After calcination, the precipitate mainly consists of iron phosphate, which basically meets the requirements of an iron phosphate precursor. [ABSTRACT FROM AUTHOR]

The purilication and reuse ol titanium dioxide by-product lerrous sullate are ol great signilicance lor improving the added value ol the iron-containing products and the comprehensive utilization of resources. The removal ol manganese and the reuse of iron in titanium dioxide by-product lerrous sullate were studied. The leasibility ol oxidizing Fe2+ to Fe'十 by hydrogen peroxide and oxidizing Mn2+ to Mn02 by potassium permanganate was theoretically analyzed. The effects ol oxidant dosage, pH value ol the solution and reaction time on the removal rate ol manganese were investigated. The experimental results show that the manganese removal rate could reach 99. 9% under the conditions ol KMnO4 dosage 1. 0 times ol the theoretical value, pH value ol 1. 20 and oxide reaction time lor 30 min. The manganese content in the purified ferric sullate solution was reduced to 0. 28 mg/L alter manganese removal treatment The purified solution was used as the iron source to synthesize iron phosphate by liquid-phase precipitation method, and the nanoscale high-purity amorphous iron phosphate dihydrate precursor was obtained, which can be transformed into a-quartz-type iron phosphate alter calcination. [ABSTRACT FROM AUTHOR]

Sulfuric acid method is a critical method to prepare rutile and anatase titanium dioxide. In the preparation process, acid leaching is accompanied by a large amount of iron-containing solid waste, represented by ferrous sulfate waste. If these solid wastes are stored directly without proper treatment, they will cause massive environmental damage and a lot of iron resources waste. The impurity removal and high added value utilization of ferrous sulfate had been studied deeply. Based on those studies, separation impurities from ferrous sulfate waste with various phosphate radical precipitation separation method was further explored. And a new process of preparing iron phosphate (FePO4) electrode material by liquid phase precipitation method was proposed to recover Fe from solid waste. Results showed that recovery of Fe in solid waste achieved 92%; moreover, removal rates of Ti, Mg, and Mn are higher than 95.3%, 78.4%, and 89.2%, respectively. The prepared iron phosphate reached the industrial battery grade (HG/T 4701-2014) standard by liquid phase reaction. The process realized efficient recovery of iron from solid waste and high value-added utilization of iron-containing solid waste. [ABSTRACT FROM AUTHOR]

[Display omitted] The high binding affinity of iron(oxyhydr)oxides for phosphate has recently been used in medicine to treat hyperphosphatemia, an abnormally elevated phosphate concentration in the blood. For iron(oxyhydr)oxide nanoparticles, the composition of the organic shell has a more significant influence on their interaction with phosphate than is often assumed. This study shows different mechanisms in phosphate binding, using the example of two similar new phosphate-binding agents. We characterized the phosphate-binding behavior of two iron(oxyhydr)oxide-based nanomaterials with similar composition and particle properties and investigated their binding mechanisms by spectroscopic methods. For the often prescribed Velphoro, we demonstrated a phosphate binding capacity of>210 mg/g. A similar active ingredient named C–PAM binds over 573 mg/g. Spectroscopic measurements highlighted differences in the binding mechanism. While Velphoro binds phosphate via surface complexation independent of pH and adsorbent concentration, C–PAM shows a strong concentration dependence. At low concentrations, phosphate is bound via complexation reactions. The iron(oxyhydr)oxide structure was dissolved at higher phosphate concentrations and formed various iron phosphate species. The substances behave differently upon interaction with phosphate, although being very similar in composition and crystal structure. Thus, we demonstrated a crucial influence of the ligands in the shell on the binding mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recycle mixed spent LIBs by their own intrinsic redox properties. • Phosphoric acid is used as leaching agent to promote the formation of FePO 4. • Over 97% of valuable metals and high-purity FePO 4 can be recovered in one step. • The amount of phosphoric acid can be reduced to 0.88 mol/L. The recovery of valuable elements in spent lithium-ion batteries (LIBs) has attracted more and more attention. Efficient recovery of valuable elements from spent LIBs with lower consumption and shorter process is the target that people have been pursuing. In this study, the valuable metals (Ni, Co, Mn and Li) and FePO 4 products are simultaneously recovered from mixed spent LiNi x Co y Mn z O 2 and LiFePO 4 in one step under the optimized condition of 0.88 M H 3 PO 4 , a mass ratio of LFP/NCM of 2:1, a L/S ratio of 33:1 and 80 ℃ for 120 min without additional auxiliary reagents. Over 60 % of acid consumption is reduced and the process of adjusting pH is avoidable. The leaching efficiencies of the valuable elements reach up to 99.1 % for Ni, 98.9 % for Co, 99.6 % for Li and 97.3 % for Mn. Almost all of Fe is precipitated as FePO 4 ·2H 2 O. By means of the empirical model, the research on leaching kinetics demonstrates that the leaching reaction is internal diffusion-controlled with the apparent activation energy of valuable metals less than 30 kJ/mol. Furthermore, the redox reaction mechanism between spent LiBs has been explored. And the intrinsic driving force in the phosphoric acid system is found out. This finding may provide an innovative and selective recycling method for valuable elements from mixed spent LIBs with high economic benefit and fewer environmental footprints. [ABSTRACT FROM AUTHOR]

Batteries made of charge carriers from Earth‐crust abundant materials (e.g., Na, K, and Mg) have received extensive attention as an alternative to Li‐ion batteries for grid storage. However, a lack of understanding of the behavior of these larger ions in the electrode materials hinders the development of electrode structures suitable for these large ions. In this study, we investigate the impact of alkali ions (Li, Na, and K) on the redox chemistry and mechanical deformations of iron phosphate composite cathodes by using electrochemical techniques and in situ digital image correlation. Na‐ion and Li‐ion intercalation demonstrate a nearly linear correlation between electrochemical strains and the state of charge and discharge. The strain development shows nonlinear dependance on the state of charge and discharge for K ions. Strain rate calculations show that K ion intercalation results in a progressive increase in the strain rate for all cycles. Li and Na intercalation induce nearly constant strain rates with the exception of the first discharge cycle of Na intercalation. When the same amount of ions are inserted into the electrode, the electrode shows the lowest strain generation upon Li intercalation compared to larger alkali ions. Na and K ions induce similar volumetric changes in the electrode when the state of charge and discharge is around 30%. Although the electrode experiences larger absolute strain generation at the end of the discharge cycles upon Na intercalation, strain rates were found to be greater for K ions. Potential‐dependent behaviors also demonstrate more sluggish redox reactions during K intercalation, compared to Li and Na. Our quantitative analysis suggests that the strain rate, rather than the absolute value of strain, is the critical factor in amorphization of the crystalline electrode. [ABSTRACT FROM AUTHOR]

A bifunctional and high‐efficiency solid acid catalyst(S‐SBC) was prepared from papermaking sludge by calcining and sulfonation with concentrated sulfuric acid. The monoclinic FePO4 was added to assist S‐SBC to improve HMF yield. The structure characterization of S‐SBC and its catalytic performance for 5‐hydroxymethylfurfural(HMF) preparation from fructose, glucose and cellulose were investigated. Metal ions and −SO3H in the S‐SBC had synergistic effects on the HMF yield. The HMF yield from fructose, glucose and cellulose were respectively 90.3 %, 73.7 % and 28.8 % with S‐SBC alone. The combination of monoclinic FePO4 and S‐SBC could effectively improve the yield of HMF from glucose and cellulose. The highest yield of HMF from glucose and cellulose were respectively 89.5 % and 53.3 % with the binary catalysts. The mechanism of the synergistic action of the binary catalysts was proposed. Bronsted acid from metal ions hydrolysis and ‐SO3H, ‐COOH, ‐OH grafted on the surface of biochar promoted hydrolysis of cellulose to glucose, which was then coordinated with Lewis acids and isomerized to fructose. Finally, HMF was obtained by dehydrating from fructose. [ABSTRACT FROM AUTHOR]

[Display omitted] • The optimized V-doped FeP nanoflowers are prepared for enhanced HER. • V doping lowers d-band central position and hydrogen formation energy barrier. • V-FeP shows low overpotentials of 290 mV to deliver 1000 mA cm−2 for 24 h. • Over 100-h stability at 1000 mA cm−2 for water electrolysis is obtained. Reasonable design of hydrogen evolution reaction (HER) electrocatalyst from the perspective of electronic structure is a vital way to optimize the catalytic activity. Mono-metallic iron-based phosphates have been shown to be active toward HER, but their performance remains unsatisfactory despite their abundant reserves and low preparation cost. Here, guided by the d-band center and band structure theories, V-doped FeP nanoflower grown directly on iron foam are constructed. Combining the density functional theory (DFT) simulations with physical characterizations reveal that the enhanced HER activity is mainly attributed to the lowed d-band central position, increased water dissociation capacity, decreased hydrogen formation energy barrier and reduced charge transfer impedance. As a HER catalyst in 1 M KOH, the obtained V-FeP shows low overpotentials of ∼149, ∼246 and ∼290 mV to deliver the current densities of 100, 500 and 1000 mA cm−2 with at least 24 h. When coupled with other highly active oxygen evolution reaction (OER) catalyst (NiFe-LDH/IF), the NiFe-LDH/IF(+) || V-FeP/IF(-) pair also performs a low cell voltage and over 100-h stability at high current density of 1000 mA cm−2, which endows it a large potential in the practical electrolytic water industry. Our work may provide a reference for the enhancement of inert and low-cost HER-active iron phosphide. [ABSTRACT FROM AUTHOR]

Simple Summary: Arion vulgaris has become a major invasive pest slug in Europe, causing extensive damage to many crops. To control this pest, the use of chemical molluscicides remains the most important. However, despite the proved efficacy, they still have detrimental environmental effects. We performed two double-replicated laboratory studies testing molluscicide pellets with metaldehyde (3% and 5%) and iron phosphate (1%) and found the reluctance of slugs to eat a full lethal dose regardless of whether the poison is stronger or weaker. As a consequence, slugs remain alive and only reduce their herbivory by half; the remaining granules or their parts are the main source of toxic effects of molluscicides in the environment. Moreover, a higher metaldehyde content of the pellets does not lead to lower herbivory. The results showed that a new application of molluscicides could be useful; the application rate should be decreased according to the ability of slugs to eat a certain amount of molluscicide pellets. Arion vulgaris are mostly controlled using chemical molluscicide products, and the detrimental environmental effects of these molluscicides can be reduced by decreasing the number of pellets applied per unit area. The objective of this study was to compare three slug control methods during two double-replicated seven-day laboratory experiments, in which slugs could choose the number of pellets with metaldehyde (3% or 5%) or iron phosphate (1%) and different types of food: leafy plants (lettuce), root vegetables (carrot), a cereal-based diet (oatmeal), or an animal-based diet (dry cat food). Slugs were irrigated and allowed to recover. We found a reluctance of slugs to eat big amounts of pellets and, therefore, to reach a full lethal dose, which resulted in low mortality (the rate was only 2.1%), regardless of whether the poison was stronger or weaker. Herbivory of slugs was in some cases reduced by half, but no treatments resulted in slugs to stop eating. Pellets with 3% metaldehyde were significantly more acceptable than pellets with 5% metaldehyde (uneaten pellets were left). The results showed that the new application of molluscicides could be useful; the application rate should be decreased according to the slugs number and ability of slugs to eat a certain amount of molluscicide pellets. [ABSTRACT FROM AUTHOR]

[Display omitted] • Utilizes titanium extraction tailing as a sustainable source for high-quality iron phosphate production. • Efficient separation of iron and titanium is achieved through co-leaching. • The contents of impurities in the product were far below the standard. • Formation of [Fe(HPO 4) 2 ]- complexes in acid leaching promotes iron dissolution, enhancing the efficiency of iron extraction. This study presents a compelling, eco-friendly methodology for extracting valuable materials from titanium extraction tailing (TET) discharged from the reduction rust process. The process efficiently separates titanium and iron by utilizing a co-leaching technique with sulfuric and phosphoric acids. This method results in a high-grade titanium dioxide (TiO 2) with a purity of 61.57 % and an iron leaching rate surpassing 96 % under the optimal conditions of the liquid-to-solid ratio of 4:1, a leaching temperature of 70 °C, and a specific phosphoric acid to iron molar ratio is 1.1. The subsequent refinement phase involves adjusting the pH to 2.0 using ammonia, coupled with controlled precipitation temperature and ageing time, leading to the production of battery-grade iron phosphate (FePO 4) with a purity of 98.82 %, in line with the stringent HG/T4701-2014 standards. The material's phase analysis and morphological characterization confirm its high crystallinity and minimal impurity levels. Moreover, the co-leaching approach facilitates magnetite dissolution, effectively enriching the rutile content in the leach residue and concurrently minimizing the formation of ammonium sulfate salts, thereby enhancing the purity of the iron phosphate. These technological advancements contribute to resource recovery research and offer new avenues for industrial material production, laying a solid foundation for sustainable industrial applications. [ABSTRACT FROM AUTHOR]

FePO 4 (FP) as a precursor of lithium iron phosphate batteries has been mass-produced in recent years and may face the problem of overproduction. Also, the phosphorus removal process in wastewater treatment plants produces large amounts of sludge containing FP. It is a huge waste of both iron and phosphorus resources if such FP cannot be utilized. This work explores a new strategy for utilizing FP to activate sulfite (S(IV)) autoxidation for simultaneous pollutant degradation and phosphorus release in water. Acid orange 7 (AO7) and several pharmaceutical and personal care products (PPCPs) were chosen as the target pollutants for the FP‒S(IV) system and the influence of pH, FP and S(IV) dosage were investigated. Typically, up to 89.5% AO7 (10 mg L−1) and above 60% PPCPs (10 μM) were oxidized within 90 min by adding 1 g L−1 FP and 2 mM S(IV) into the water at the initial pH 4.0. Results of quenching experiments and electron spin resonance analysis confirmed SO 5 •− as the dominant reactive species for AO7 oxidation. Meanwhile, two stages of phosphorus release from FP were observed along with the AO7 oxidation and their linear correlation over the pH range 3.0–8.0 was proven. The first stage (0–5 min) was thought to be dependent on the initial pH and was obviously faster than the second stage (10–45 min), whose rate increased linearly with S(IV) dosage. Phosphorus released high up to 24.3 μM at 90 min with 4 mM S(IV). Moreover, the mechanisms of FP activated sulfite autoxidation as well as phosphorus release were proposed, and the AO7 degradation pathway was investigated. This study provides a novel possibility for FP waste utilization and potential recovery of phosphorus resources. [Display omitted] • Simultaneous pollutant oxidation and P release were achieved in FePO 4 –S(IV) system. • SO 5.•− was predominately responsible for the removal of acid orange 7. • P release was correlated with the oxidation of acid orange 7 at various pHs. • Mechanisms of S(IV) autoxidation and phosphorus release were proposed. [ABSTRACT FROM AUTHOR]

The recovery and regeneration of FePO 4 from lithium extraction slag (LES) are crucial steps in the closed-loop recycling of waste LiFePO 4 batteries. This necessity arises despite the low commercial value of LES, as conventional recovery methods are cost-prohibitive, leading to insufficient attention to LES recovery. The recent surge in retired batteries has resulted in a significant accumulation of LES, posing serious environmental concerns, however, the high content of Fe and P resources in LES presents a potential value. The study begins with a theoretical analysis, concluding that the reduction leaching of LES is a feasible approach. By integrating this with the Fe powder synthesis route for FePO 4 , it is found that efficient leaching of LES can be achieved using a low concentration of H 2 SO 4 , thereby significantly reducing the recovery cost. This method not only efficiently utilize LES but also alleviates environmental pressure. The thermodynamic analysis sheds light on the mechanism of LES leaching and FePO 4 synthesis, confirming the feasibility of each reaction. Optimal leaching conditions (1.4 times the stoichiometric amount of H 2 SO 4 , 1.5 times the amount of Fe powder, an L/S ratio of 5 mL/g, and a reaction duration of 150 min at 60 °C), under which the leaching rates of Fe and P reached 94.66% and 98.23%, respectively. Additionally, the study introduces a method to remove the main impurity Al in LES, achieving a removal rate of over 99%, reducing its concentration to below 100 ppm. Other impurities, such as Ti, Mn, and Zn, also meet the Chinese Chemical Industry Standard (HG/T 4701-2021). Comparative analyses were conducted between regenerated R-FePO 4 , commercial C–FePO 4 , and untreated LES (r-FePO 4). LiFePO 4 materials derived from these sources were synthesized, followed by an evaluation of their electrochemical performance. The regenerated R-FePO 4 matched the quality of commercial FePO 4 and significantly outperformed r-FePO 4. Additionally, the process proposed in this study yields significant economic benefits, estimating a profit of 719.6 $/t of recycled LES. This research proposes a cost-effective and efficient method for regenerating high-quality battery-grade FePO 4 from LES, offering a significant contribution to the closed-loop recycling of waste LiFePO 4 batteries. • With the assistance of Fe powder, only a small amount of H 2 SO 4 is required to efficiently leach Fe and P resources from LES. • Impurities have been effectively removed, and the impurity content meets the requirements for battery-grade FePO 4. • The regenerated FePO 4 demonstrates excellent electrochemical performance comparable to commercial materials. [ABSTRACT FROM AUTHOR]

Municipal biosolids contain organic and inorganic phosphorus (P) that could be recovered for reuse as P fertilizer. Inorganic P compounds include iron phosphates that precipitate and/or adsorbed phosphate ions as a consequence of soluble iron addition in order not to exceed total phosphorus (TP) emission limits. The inorganic orthophosphate (o-Pi) minerals within biosolids can have low solubilities. One P recovery strategy is to maximize the dissolution of o-Pi from biosolids for reuse. Dissolving iron phosphates in biosolids by adding sodium sulfide was assessed as an o-Pi dissolution strategy. 10 % w/w biosolids slurries with a total phosphorus (TP) of 0.97 ± 0.03 mmol P/dry g were mixed with sulfide/TP (S2−/TP) molar ratios from 0 to 4 for up to 96 h. The maximum o-Pi concentration (48 ± 7 mM, or 42 ± 6 % of TP) was obtained for 4 S2−/TP after 24 h at room temperature (RT). Iron concentrations measured by colorimetry (ferrozine) reduced from 0.6 ± 0.1 mM to less than 0.01 mM (S2−/TP > 1). X-ray diffraction and FTIR suggest that sulfide treatment preferentially dissolved amorphous o-Pi-containing solids, vivianite, and minerals with iron, aluminum, phosphate, sulfate, and other subsitutions. Poorly crystalline erdite (NaFeS 2 ·2H 2 O) was detected in products after S2−/TP treatment ratios ≥ 2. Incubation at RT or 37 °C did not affect the o-Pi concentrations for 0 or 4 S2−/TP over 47 h. Sulfide addition could also increase the risk of construction material corrosion, and reduce the efficiency of P recovery by precipitation. There are disadvantages to using sulfide to dissolve o-Pi from biosolids as a potential P recovery process. [Display omitted] • Sulfide dissolved vivianite, amorphous, and substituted iron phosphates in biosolids. • Increasing sulfide concentration increased orthophosphate dissolution from biosolids. • Erdite (NaFeS 2.2H 2 O) was identified if the sulphide to total P molar ratios were >1. • The maximum phosphate concentration was 48 ± 7 mM for 10% biosolids, 4 S2−/TP, 24 h. • Sodium sulfide addition may not be an effective P-recovery strategy for biosolids. [ABSTRACT FROM AUTHOR]

Iron phosphate, Fe2 (HPO4)3*4H2O, is synthesized at ambient temperature, using the inorganic sol–gel method coupled to the microwave route. The experimental conditions for the gelling of Fe (III)-H3PO4 system are previously defined. Potentiometric Time Titration (PTT) and Potentiometric Mass Titration (PMT) investigate the acid–base surface chemistry of obtained phosphate. Variations of surface charge with the contact time, Q a function of T, are examined for time contact varying in the range 0–72 h. The mass suspensions used for this purpose are 0.75, 1.25 and 2.5 g L−1. The point of zero charge (PZC) and isoelectric point (IEP) are defined using the derivative method examining the variations dpH d t = f pH , at lower contact time. A shift is observed for PZC and IEP towards low values that are found to be 2.2 ± 0.2 and 1.8 ± 0.1, respectively. In acidic conditions, the surface charge behavior of synthesized phosphate is dominated by > POH ¯ group which pKa = 2.45 ± 0.15. Q against T titration method is performed for synthesized Fe2 (HPO4)3*4H2O in NaCl electrolytes. The maximal surface charge (Q) is achieved at the low solid suspension. Hence, for m = 0.75 g L−1, Q value of 50 coulombs is carried at μ = 0.1 and pH around 12, while charge value around 22 coulombs is reached in the pH range: 3–10. The effect of activation time, Q and pH on sodium insertion in iron phosphate, were fully evaluated. To determine the optimal conditions of the studied process, mathematical models are used develop response surfaces in order to characterize the most significant sodium interactions according to the variation of the pH, Q, the contact time and the contents of the synthesized material. [ABSTRACT FROM AUTHOR]

The structural transformation of FePO 4 from the trigonal berlinite phase to the orthorhombic CrVO 4 phase has been studied using neutron diffraction at high pressure and high-temperature. The berlinite structure was compressed to a pressure of 5.2(2) GPa and amorphisation observed. Upon annealing at temperatures above 798(28) K the high pressure FePO 4 structure was observed to form. This lowers the formation temperature required to promote this phase over the amorphous phase by ∼100 K compared to previous reports. No other structured phases were observed during the formation process which implies that the CrVO 4 structure is the most stable form at high pressures and is kinetically inhibited from forming at low temperatures. [ABSTRACT FROM AUTHOR]

The penultimate aim of all analytical techniques is to provide best quantitative information with high sensitivity and accuracy. Such techniques then can be ideal to estimate the concentration of different species in a sample or to measure the surface concentration and so on. The preliminary step involved in quantitative analysis is evaluation of the system response for a given amount of the analyte under investigation. Different methodologies are proposed and executed for the above mentioned purpose. In this work, we have demonstrated the performance of chemometric methods to study the atomic emissions from simulated nuclear waste glasses. Five samples of iron‐phosphate glasses were synthesized by doping Cr, Sr, and Ti at various concentrations. The spectra recorded using laser‐induced breakdown spectroscopy (LIBS) system were analyzed using principal component analysis (PCA), partial least square‐discriminant analysis (PLS‐DA), and support vector machines (SVM) for the classification. As compared with the PLS‐DA, SVM provided better results for classification with accuracy of 100% on both calibration and validation sets, respectively. The quantitative analysis of glass samples is carried out using partial least square regression (PLSR) and support vector regression (SVR). The root mean squared error of prediction (RMSEP) is found to be 0.16, 0.20, and 0.08 (wt%) for Cr, Sr, and Ti using PLSR. The detailed investigation elucidates the advantages of chemometrics in handling the complex LIBS spectrum of glass samples and their significance in process control of nuclear waste, nuclear forensics, and so on. The performance evaluation of chemometric methods to study the atomic emissions from simulated nuclear waste glasses. [ABSTRACT FROM AUTHOR]

Iron phosphate in the composition of concentrate is a fairly strong chemical compound. However, with the help of gaseous substances, such complex compounds decompose when heated to the required temperature, which contributes to the reduction of not only iron, but also phosphorus. Hydrogen and carbon monoxide were used as gaseous reducing agents. This article describes in detail the thermodynamic analysis of the reduction of phosphorus from iron phosphate, its interaction with hydrogen and carbon monoxide. [ABSTRACT FROM AUTHOR]

The preparation and structural characterization of three new iron phosphates with general formula Rb3M3Fe5(PO4)8 (M = Mn, Co, Ni) labeled: I, II and III respectively, are reported. Single crystals X-ray diffraction reveals that these compounds crystallize in an original structure, which adopts the monoclinic system with space group C2/c. The unit cell parameters are: a = 19.945(1) Å; b = 14.935(7); c = 9.995(1) Å; β = 119.10(3)° for I, a = 19.826(1) Å; b = 14.948(1); c = 9.927(1) Å; β = 117.14(1) ° for II and for III a = 19.792(2) Å; b = 14.833(2); c = 9.908(2) Å; β = 119.28(2)°. The structures consist of MO6 and (M,Fe)O6 octahedra, linked through common edges to form [M2(M,Fe)2O16]∞ crossing chains running along the [1 1 2] and [1 − 1 2] directions. These chains are interconnected by the FeO6 octahedra and PO4 tetrahedra, generating a 3D framework with intersecting tunnels where the Rb+ cations are located. This paper report the synthesis and the structural study of three new alkali iron phosphates Rb3M3Fe5(PO4)8 (M = Mn, Co, Ni). A projection of the Rb3M3Fe5(PO4)8 (M = Mn, Co, Ni) structure along the [112] direction. [ABSTRACT FROM AUTHOR]

• A novel process is adopted to recovery of Li 2 CO 3 and FePO 4 /C from spent LiFePO 4. • Li in the spent LiFePO 4 can be extracted without any chemical reagent. • The recovered Li 2 CO 3 and FePO 4 /C can be used for resynthesized LiFePO 4. • The resynthesized LiFePO 4 meets the basic requirements for reuse. A simple, green and effective method, which combined lithium iron phosphate battery charging mechanism and slurry electrolysis process, is proposed for recycling spent lithium iron phosphate. Li and FePO 4 can be separation in anionic membrane slurry electrolysis without the addition of chemical reagent. The leaching efficiency of Li can reach to 98% and over 96% of Fe are recycled as FePO 4 /C. Kinetics analysis indicates that the surface chemical reaction is the control step during the slurry electrolysis. Additionally, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Electrochemical Impedance Spectroscopy (EIS) characterization and thermodynamic analysis are employed to investigate the leaching mechanism. It is found that the spent LiFePO 4 is delithiated and oxidized to FePO 4 by the function of e −, which is similar as the LiFePO 4 battery charging process. EIS analysis also verify the kinetics results, the charge transfer resistance controlled the leaching process. Finally, a novel process for recovery of spent LiFePO 4 is proposed. The recovered Li 2 CO 3 and FePO 4 /C can be used for resynthesize LiFePO 4 , and the resynthesized LiFePO 4 exhibits reversible capacities of 143.6 mAh g−1 at 1C and high current efficiency, stable cycle performances at 0.1 and 0.5C which meets the basic requirements for reuse. [ABSTRACT FROM AUTHOR]

A comparative study of the activation of n-hexane over 12-molybdophopshoric acid (H3PMo12O40 or HPA), Fe3+ doped HPA (Fe0.69H0.93PMo12O40) and an iron phosphate catalyst (P/Fe = 1.22) was carried out. The Fe doped HPA catalyst is thermally more stable and less acidic than the unmodified HPA catalyst. The HPA and the Fe doped HPA catalysts both catalytically produced 2,5-dimethyltetrahydrofuran and 2,5-hexadione (oxygenates), with the Fe doped HPA catalyst selectively producing more oxygenates than the HPA catalyst. The iron phosphate catalyst produced cis-2-hexene and 1-hexene but no oxygenates, which implies that the iron phosphate catalyst promotes dehydrogenation, but not oxygen insertion. At 360 °C, the HPA catalyst initiated benzene formation reactions. At isoconversion of ca. 8% under isothermal conditions, the iron phosphate catalyst gave the highest selectivity (72%) towards benzene, which may have formed through both catalytic and non-catalytic reactions. In contrast, the Fe doped HPA catalyst showed a lower benzene selectivity than the HPA catalyst with a corresponding increase in cyclic oxygenates. [ABSTRACT FROM AUTHOR]

Large amounts of perfect crystals were excavated from ancient coffins dating 2510 (±50) bp, in Jing'an County, Jiangxi Province, China. The coffins were wrapped by multiple bamboo mats and sealed highly by waterproof soil layers. In this study, crystals, wooden coffins, surrounding water and clay materials of several buried wooden coffins were subject to various analyses, and the crystals were identified to be vivianite by single crystal X‐ray diffraction, X‐ray fluorescence (XRF) and infrared (IR) spectroscopy. Spatial distribution of the vivianite crystals, which was consistent with first Fick's diffusion principle, indicated that the phosphate (PO43−) of the vivianite was originated from human bone that was demineralized under an acidic clay condition. Spatial distributions of iron(III) oxide (Fe2O3) and iron(II) oxide (FeO) indicated that iron(II) cations (Fe2+) of the vivianite originated from clay outside the coffins. Perfect vivianite crystals were formed at an extremely slow rate within the highly sealed coffins, in which Fe2+ and PO43− concentrations were of such a low level that the rapid precipitation of imperfect vivianite crystals was prevented, as the clay colloid could infiltrate only along the limited passageways of jointed seams between two halved timbers of the coffins. [ABSTRACT FROM AUTHOR]

• The mechanism of ethane and ethene oxychlorination is assessed on iron phosphate. • Ethane yields ethene via ethyl chloride, while ethene directly forms vinyl chloride. • Ethane acts as a vinyl chloride suppression agent in ethene oxychlorination. • Active site competition favors ethane, depleting sites for ethene activation. • The diverging selectivity patterns are translatable to other catalytic systems. In the context of vinyl chloride monomer (VCM) production, an oxychlorination catalyst that allows direct VCM formation from gas-derived ethane instead of expensive oil-derived ethene is intensively sought after. A wide range of stable ethane oxychlorination catalysts for this purpose have recently been reported, yet they mainly yield ethene, while VCM remains a minor by-product. Strikingly, the same catalysts are active in ethene oxychlorination, resulting in selective VCM formation under equivalent reaction conditions. This work reveals the origin of these diverging selectivity patterns by combining quantitative catalytic tests, temporal analysis of products (TAP), and density functional theory (DFT) on iron phosphate. Ethane oxychlorination is found to proceed sequentially through ethyl chloride (EtCl) dehydrochlorination to ethene, while ethene oxychlorination directly yields VCM without formation of the intermediate dichloroethane (EDC) on iron phosphate. Furthermore, by co-feeding ethane in ethene oxychlorination, we demonstrate that the alkane suppresses the formation of VCM in ethene oxychlorination. The reason for this VCM inhibition is found in the hydrocarbon competition for a combination of the active, free and chlorinated iron centers. As ethane activation exhibits half of the barrier of ethene activation, the presence of ethane leads to active site depletion, hindering VCM formation. These observations are extended by ethane co-feeding tests in ethene oxychlorination over a wide range of known oxychlorination catalysts (EuOCl, LaOCl, CeO 2 , and CuCl 2 -KCl-LaCl 3 / γ -Al 2 O 3), and corresponding DFT calculations, indicating that the described phenomenon is material independent. The gathered molecular-level understanding explains the major hurdle of using ethane as feedstock for vinyl chloride production. [ABSTRACT FROM AUTHOR]

New RbNiFe(PO 4) 2 phosphate, both in single and powder forms, was synthesized by flux method and solid state reaction. It is characterized by crystal-X-ray diffraction, HRTEM, IR and Raman spectroscopy and UV-diffuse reflectance. Its crystal structure adopts the monoclinic P 2 1 / c space group with the cell parameters: a = 5.134(4) Å, b = 14.547(2) Å, c = 9.230(2) Å; β =103.76(3) ° and Z = 4. The RbNiFe(PO 4) 2 framework has a three-dimensional structure, consisting of chains of edge-sharing NiO 6 , isolated FeO 5 and PO 4 tetrahedra sharing vertices and edge to form large tunnels along the [100] direction, where Rb + cations are placed. The IR and Raman data are in good agreement with the number of PO 4 groups determined in crystal structure. Diffuse reflectance spectroscopy leads to a gap energy of 3.15 eV. It also proved the presence of isolated Fe3+ ions from low energy due to the inter-electronic transition from oxygen to Ni (II) and the non-existence of d-d transition related to iron. The colorimetric properties of the compound result mainly from d-d visible transitions related to the Ni2+ cation in octahedral coordination. The magnetic study revealed that below the temperature of T N =21K an antiferromagnetic character appears with a Curie-Weiss constant of Ө = −97 K. [Display omitted] • A new iron phosphate RbNiFe(PO 4) 2 was synthetized in both single crystal and powder forms using flux and solid state methods respectively. • The crystal structure was investigated by X-ray diffraction analysis. • The structural study shows a 3D framework with large six-sided tunnels. • UV–visible spectra was reported and d-d transitions were assigned. • Magnetic susceptibility was investigated. [ABSTRACT FROM AUTHOR]

Materials based on amorphous iron(III) phosphate have been prepared via precipitation in an aqueous medium and microemulsion, as well as in a microemulsion in the presence of a mesoporous carbon material. Heat treatment of amorphous FePO4 leads to the formation of the hexagonal phase of crystalline FePO4. It has been shown that sodium intercalation under operating conditions of sodium ion batteries is more effective in the case of materials based on amorphous FePO4. The discharge capacity of the material based on amorphous FePO4 synthesized by the microemulsion method in the presence of the G_157M mesoporous carbon material is ~183 mAh/g and is the sum of the capacity due to sodium intercalation into FePO4 and that due to the reduction of functional groups on the surface of the mesoporous carbon. [ABSTRACT FROM AUTHOR]

Abstract The effect of barium oxide on the structure of iron phosphate glass was investigated by Raman spectroscopy to understand the better thermal stability of barium loaded iron phosphate glasses compared to iron phosphate glass containing caesium oxide. Glasses with composition (mol %) of 36.1 Fe 2 O 3 -54.1 P 2 O 5 - 9.8BaO and 32.2 Fe 2 O 3 -48.3 P 2 O 5 - 19.5BaO revealed the existence of higher concentration of meta phosphate linkage, which could be a reason for their enhanced thermal stability. In addition, the enthalpy increment data were obtained by isoperibol drop calorimetry on these glasses. These data of barium oxide loaded iron phosphate glasses were compared with those of caesium loaded iron phosphate glasses. The specific heat of pristine IPG is always higher than that of IPG containing either BaO or Cs 2 O, showing the effect of modifiers (Ba2+ or Cs+) in glass. Depending on the concentration of the modifier, the density of the glass changes and higher the density lower was the specific heat of the glass. Highlights • Presence of meta phosphate linkage in Ba loaded iron phosphate glass. • Better thermal stability of Ba loaded compared to Cs loaded glasses. • ∆T = T x -T g was used as an indicator for quantifying the thermal stability of glasses. • Glasses with higher density showed lower specific heat. [ABSTRACT FROM AUTHOR]

Purpose: Citrus white snail, Helicella candeharica Pfeiffer (Panpulmonata: Helicidae) is one of the most important orchard pests. In this study, the effectiveness of mineral oil was compared with molluscicide baits such as metaldehyde, ferricole (iron phosphate) and a snail-repellent paint in a commercial citrus orchard in northern Iran to reduce access of citrus white snails to citrus trees. Materials and methods: The number of snails on citrus trees was monitored and counted 10 days after the application of the treatments, and at an interval of 6-8 days up to harvest time. Results: In the first study, the mineral oil and repellent paint treatments reduced a number of snails best. In the second study, using metaldehyde and mineral oil barrier, again the mineral oil barrier reduced snails best. The cost of each treatment during one season per hectare was calculated at 55, 153, 124 and 120 $/ha for mineral oil, iron phosphate, snail-repellent paint and metaldehyde, respectively. Conclusions: Mineral oil is an effective alternative for chemical compounds for reducing access by H. candeharica to citrus trees. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The development of efficient and earth-abundant electrocatalysts for overall water splitting is important but still challenging. Herein, iron phosphate (FeP i) electrode is synthesized using a successive ionic layer deposition and reaction (SILAR) method on a nickel foam substrate at room temperature and is used as a bifunctional electrocatalyst for water splitting. The prepared FeP i electrodes show excellent electrocatalytic activity and stability for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The FeP i electrode exhibits low overpotential of 230 mV and 157 mV towards the OER and HER, respectively, with superior long-term stability. As a result, an electrolyzer that exploits FeP i as both the anode and the cathode is constructed, which requires a cell potential of 1.67 V to deliver a 10 mA cm−2 current density in 1 M KOH solution. The exceptional features of the catalyst lie in its structure and active metal sites, increasing surface area, accelerated electron transport and promoted reaction kinetics. This study may provide a facile and scalable approach to design a high-efficiency, earth-abundant electrocatalyst for water splitting. [ABSTRACT FROM AUTHOR]

In order to encapsulate nuclear wastes (NW) enriched in Uranium, they have been designed and obtained vitrified matrices of iron aluminum phosphates including substitution of U by Bi. These glasses have been designed and obtained formulating all from the starting binary composition: 60P 2 O 5 ·40Fe 2 O 3 where the Fe/P ratio was 0.67. The thermal behavior has been investigated by DTA/TG analysis and thermal expansion, as well as identification of some phases by TEM/EDS. The vitrified structures are difficult to crystallize as is the case of the (Fe + U) contents in the range of 0.50 per P atom. Glasses with Bi-oxide are less resistant to crystallization than those containing U. The glasses here investigated depict a reasonable water chemical stability due to the high percentage of P O Fe O bonds and the presence of U (4+ to 6+). Lately, it has been also investigated the calcination of simulated miniplates of Si 2 U 3 /Al having additions of these glasses and U 3 O 8 to dilute this Uranium enriched in MTR combustible (Material Testing Reactor). [ABSTRACT FROM AUTHOR]

The efficient and inexpensive extraction of Ni and Co from limonitic laterite ore is becoming imperative due to the rapidly growing demand for nickel and cobalt driven by electric vehicles (EVs). In this work, powdery Ni-Co-Fe alloy was prepared from limonitic laterite via reductive roasting followed by magnetic separation, with nickel and cobalt recoveries of 91.9% and 93.3%, respectively. Most of the gangue material was rejected, and the obtained powdery alloy was readily dissolvable in sulfuric acid solution at atmospheric pressure. Under the conditions of 2.5 M H 2 SO 4 , 80 °C, 60 min, L/S ratio of 8 mL/g, the extractions of Ni, Co and Fe were 98.5%, 99.9% and 95.6%, respectively, and chemical reaction was the rate-controlling step. The proposed process is promising for the utilization of limonitic laterite ore with high leaching efficiency and less leach residue discharge. • Ni, Co and Fe leaching ratios from powdery Ni-Co-Fe alloy were 98.5%, 99.9% and 95.6%, respectively. • Leaching of Ni, Co and Fe were controlled by chemical reaction. • Value-added iron phosphate product was obtained. • The total recoveries of Ni and Co were 90.5% and 93.2%, respectively, from laterite ore. [ABSTRACT FROM AUTHOR]

[Display omitted] • An acid-assisted electrolysis method was used for recovery of Li+ from LFP powder. • Selective leaching could be achieved by suspension electrolysis. • The optimal leaching efficiencies of lithium and iron ions were 99.89 % and 0.09 %. • The leaching process was successively controlled by chemical reaction and diffusion. • High-purity Li 3 PO 4 with a recovery rate of 88.46 % could be obtained. In recent years, electric vehicle is greatly flourishing, while lithium iron phosphate batteries are vigorously developed due to their low cost and high stability. Since it is expected that the first batch of lithium iron phosphate (LFP) batteries will be retired at the peak in 2025, it is crucial to develop an environmentally and efficient recycling method. In this study, an acid-assisted electrochemical extraction method of lithium ions from LFP powder was proposed. Part of the LFP powder was leached directly by acid, and the leached ferrous ions were separated by oxidation precipitation and electroplating. The remaining LFP powder was directly oxidized by the anode to release lithium ions. The leaching efficiency of lithium ion reached up to 99.89 % and the leaching efficiency of iron ion was kept at a very low value of less than 0.2 %. The selective separation of lithium ion can be efficiently achieved during the leaching process. After evaporation and concentration, the lithium ions were recovered as product of high-purity lithium phosphate. Compared with other recycling methods, the proposed recovery method used less reagents and generated little waste. This process presents a novel green recycling pathway for the potentially selective leaching and recovery of spent LFP batteries. [ABSTRACT FROM AUTHOR]

The sodium intercalation of mixed – valence iron phosphate Fe 3 2+ Fe 4 3+ (PO 4 ) 6 results in drastic transformation of its physical properties. The parent compound Fe 7 (PO 4 ) 6 reaches magnetically ordered state through succession of phase transitions at T N1  = 45.5 K and T N2  = 16 K marked by sharp singularities in both specific heat C p and magnetic susceptibility χ. The introduction of sodium suppresses the formation of antiferromagnetic state down to T N  = 33 K in Na 0.65 Fe 7 (PO 4 ) 6 . The low temperature phase transition in this compound smears being substituted by broad anomalies in magnetization and specific heat related to the spin/charge disorder effects. The sharp well resolved electron spin resonance spectra in parent material transform into asymmetric broad line in sodium – intercalated substance. The dielectric permittivity ε of Fe 7 (PO 4 ) 6 demonstrates a kink at T N2 , while no singularity marks T N1 . No features accompany magnetic phase transition in dielectric property of Na 0.65 Fe 7 (PO 4 ) 6 but ε reaches the relaxation maxima at high temperatures which can be attributed to the freezing of sodium ions. [ABSTRACT FROM AUTHOR]

The phosphoric acid addition effect on phosphate insulation coating microstructure was investigated in this study. The relationships between the phosphate insulation coating microstructure and temperature resistance, corrosion resistance and magnetic properties of iron-based soft magnetic composites (SMCs) were studied by using SEM, TEM/EDS and FTIR. It was observed that an iron phosphate/carbonyl iron core/shell structure is formed with carbonyl iron powder after phosphatizing treatment. The iron phosphate phase was identified as amorphous and its thickness increased from 30 nm to 60 nm as the phosphoric acid concentration was increased from 1 wt% to 2 wt%. When the phosphoric acid concentration was further increased to 5 wt%, the excess iron phosphate precipitates between the soft magnetic composite particles. The temperature and corrosion resistance and resistivity of the iron-based SMCs can be effectively improved using carbonyl iron powders after phosphatizing. The initial permeability of the iron-based SMCs decreased with increasing phosphoric acid concentration due to thicker insulation layer formation. However, the imaginary permeability below the domain wall displacement resonance frequency decreased with increasing phosphoric acid concentration. The DC-bias superposition characteristic can also be improved by increasing the phosphoric acid concentration. Iron-based SMCs with superior temperature and corrosion resistance, initial permeability, magnetic loss and DC-bias superposition characteristics can be obtained by controlling the phosphoric acid concentration during phosphatizing to adjust the iron phosphate precipitate thickness on the iron powder surface. [ABSTRACT FROM AUTHOR]

Crystallization behaviour in 10 and 20 mass% BaO-loaded iron phosphate glasses was studied using differential thermal analysis technique under non-isothermal conditions. Activation energy of crystallization was estimated from the experimental data by applying isoconversional method of kinetic analysis. Activation energy of crystallization was found to increase in 10 mass% BaO-loaded iron phosphate glass, whereas the activation energy showed a decreasing trend as a function of fraction of crystallization ( α) in 20 mass% BaO-loaded iron phosphate glass. Fe(PO) was found to be the major product of crystallization in both the BaO-loaded iron phosphate glasses, and other products of crystallization varied depending on the composition of the glass. The concentration of Fe was estimated based on the contribution of various identified products of crystallization and composition of the parent glass. The estimated concentration of Fe ions was 19 and 22% after the heat treatment of 10 and 20 mass% BaO-loaded iron phosphate glasses, respectively. The crystallization behaviour of BaO-loaded iron phosphate glass is compared with iron phosphate glass and iron phosphate glass containing equivalent concentration of CsO. The activation energy of crystallization of BaO-loaded glasses was relatively higher than that of CsO-loaded iron phosphate glass. The results and comparison on crystallization of these glasses are presented in this paper. [ABSTRACT FROM AUTHOR]

Iron hydroxyl phosphate (Fe 3 (PO 4 ) 2 (OH) 2 ) microspheres with diameters of several micrometers have been successfully prepared using Fe(NO 3 ) 3 ·9H 2 O and NaH 2 PO 4 ·2H 2 O in a mixed solvent of deionized water and glycerin by a facile one-step solvothermal method. The crystal phase of the product changes from poorly crystallized FePO 4 ·2H 2 O nanoparticles into well-crystallized Fe 3 (PO 4 ) 2 (OH) 2 microspheres as the amount of glycerin increases. The as-prepared Fe 3 (PO 4 ) 2 (OH) 2 microspheres can transform into FePO 4 through thermal treatment at 800 °C in air. The cytotoxicity tests show that the as-prepared Fe 3 (PO 4 ) 2 (OH) 2 microspheres have good biocompatibility. We expect that the as-prepared Fe 3 (PO 4 ) 2 (OH) 2 microspheres are promising for the applications in various fields. [ABSTRACT FROM AUTHOR]

Iron hydroxyl phosphate hydrate Fe 1.19 (PO 4 )(OH) 0.57 (H 2 O) 0.43 (FPHH) was obtained by hydrothermal synthesis at 220 °C for 6 hours. Addition of carbon black to the solution before hydrothermal treatment led to a reduction of the FPHH particle size from ∼10 μm in the carbon-free compound to ∼300–500 nm in the FPHH-10%C and FPHH-20%C composite with a good dispersion of conducting carbon black. X-ray diffraction, 57Fe Mossbauer spectroscopy and a thermal decomposition study showed that the addition of carbon black did not interfere with the formation of the FPHH phase. Thanks to its favorable microstructural characteristics, the FPHH-10%C and FPHH-20%C material exhibited good performance as positive electrode for Li-ion battery, with high initial discharge capacities of 150, 128 and 112 mAh g −1 at 0.25C, 0.5C and 1C rates respectively and 99% capacity retention after 150 cycles at 2C. These results show that addition of solid carbon directly into the solution prior to hydrothermal treatment is a simple and effective way to reduce particle size and also to improve electronic conductivity by dispersing conductive carbon around the active material. This approach is easily transferable to other compounds prepared by hydrothermal synthesis, in order to control particle size while retaining the advantage of crystallization at low temperature. [ABSTRACT FROM AUTHOR]

A type of biochar-supported iron phosphate nanoparticle stabilised by a sodium carboxymethyl cellulose (CMC@BC@ Fe 3 (PO 4 ) 2 ) composite was synthesised to remediate cadmium (Cd)-polluted soil. The surface morphology and functional groups of the composite were characterised by scanning electron microscopy and Fourier transform infrared spectrometry, respectively. Batch experiments showed that the composite (soil-to-solution ratio 1 g:10 mL) could effectively immobilise Cd in soil. The immobilisation efficiency of Cd was 81.3% after 28 days of remediation, and physiological-based extraction test bioaccessibility was reduced by 80.0%. The results of sequential extraction procedures indicated that the transformation from more easily extractable Cd to the least available form was responsible for the decrease in Cd bioavailability in soils. Plant growth experiments proved that the composite could inhibit Cd uptake to the belowground and aboveground parts of cabbage mustard by 44.8% and 70.2%, respectively, thus promoting cabbage mustard growth and development after remediation. [ABSTRACT FROM AUTHOR]

Recovery of critical materials from end-of life (EOL) lithium-ion batteries (LIB) is gaining interest as demands for materials grows. Hydrometallurgical processes start with an intermediate product known as black mass which contains critical materials of interest (Co, Ni, Li, and graphite) as well as impurities such as Cu, Al, and Fe. These impurities are deleterious to downstream separation processes, as well as impact functionality of the final products. These impurities effectively compete with most solvent extraction (SX) and metal recovery processes to diminish the overall yields of the desired materials. In this work, a process flowsheet is presented where a previously reported electrochemical leaching (ECL) process is followed by selective precipitation using diammonium hydrogen phosphate (DAP) to remove Cu, Al, and Fe from LIB leachate solutions. The electrochemical leach process removes Cu and produces a pH-adjusted leachate, ca. pH 2, without requiring an extra Cu extraction step. The addition of the precipitant DAP to leachate by slightly adjusting the pH to 3–4 at 45 °C, precipitates 95–99% of Al and Fe as their phosphates and the leachate retains >95% of Co, Ni and Li. After the filtration of phosphate impurities, the solution is ready for further processing, such as SX. As an unexpected result from the leachate processing, 20–30% of the Ni and Co co-crystalize as the double salt after cooling to room temperature, which could provide a shorter route to their recovery. [Display omitted] • Precipitation method removed up to 99% Al and Fe as their phosphate salts. • Iron was effectively removed when in the oxidized Fe(III) state. • Effective Al removal with minimal Co and Ni loss was found at pH 4. • Ni(II) double salts were formed under specific conditions. [ABSTRACT FROM AUTHOR]

Iron(III)-precipitates formed by Fe(II) oxidation in aqueous solutions affect the cycling and impact of Fe and other co-precipitated elements in environmental systems. Fresh Fe(III)-precipitates are metastable and their transformation into more stable phases during aging may result in the release of initially co-precipitated ions. Phosphate, silicate, Mg and Ca play key roles in determining the structure and composition of fresh Fe(III)-precipitates. Here we examine how these ions affect the structure and phosphate retention of Fe(III)-precipitates formed by oxidation of 0.5 mM dissolved Fe(II) at pH 7.0 after aging for 30 days at 40 °C. Iron K-edge X-ray absorption spectroscopy (XAS) shows that aged precipitates consist of the same structural units as fresh precipitates: Amorphous Fe(III)- or Ca-Fe(III)-phosphate, ferrihydrite, and poorly crystalline lepidocrocite. Mg, Ca, and dissolved phosphate stabilize (Ca-)Fe(III)-phosphate against transformation into ferrihydrite. Silicate further attenuates (Ca-)Fe(III)-phosphate transformation. The crystallinity of lepidocrocite formed in phosphate- and silicate-free solutions slightly increases during aging. The transformation of Fe(III)- and Ca-Fe(III)-phosphate into ferrihydrite and ongoing ferrihydrite crystallization during aging result in the release of co-precipitated phosphate. Dissolved Ca on the other hand limits phosphate concentrations to values consistent with solubility control by octacalciumphosphate. Owing to the combined effects of Ca and silicate, phosphate is most effectively retained by Fe(III)-precipitates formed and aged in Ca- and silicate-containing solutions. The results from this study contribute to an improved understanding of the formation and transformation of Fe(III)-precipitates and emphasize that the complexity of Fe(III)-precipitate dynamics in the presence of multiple interfering solutes must be considered when addressing their impact on major and trace elements in environmental systems. [ABSTRACT FROM AUTHOR]

A new iron phosphate, disodium calcium manganese(II) iron(III) tris- (phosphate), Na2CaMnFe(PO4)3, has been synthesized as single crystals by the flux technique. This compound crystallizes in the monoclinic space group C2/c. The structure belongs to the alluaudite structural type and thus, it obeys the X(2)X(1)M(1)M(2)2(PO4)3 general formula. Both the X(2) and X(1) sites are fully occupied by sodium, while M(1) is occupied by calcium and M(2) exhibits a statistical distribution of iron and manganese. [ABSTRACT FROM AUTHOR]

The presence of iron in pregnant leach solutions presents significant processing challenges. The removal of iron impurities from leach solutions by means of iron phosphate precipitation may be a feasible alternative to more conventional iron oxide/iron hydroxide precipitation processes. This study compares the performance of the iron phosphate precipitation process with that of the hematite process at different operating temperatures (40 °C–90 °C), pH conditions (pH 1–pH 3) and seeding measures for the removal of iron from a chloride leach solution. The extent of iron removal, co-precipitation of nickel and copper, and solid-liquid separation were used as performance criteria for the comparison. Seeded iron phosphate precipitation at pH 1 and 40 °C resulted in 98.8% iron removal with 0.5% nickel and 2.8% copper losses. 99.8% iron removal was achieved with the iron phosphate precipitation process at pH 1 and 80 °C, but the nickel and copper losses increased to 8.7% and 20.8%, respectively, with the increase in temperature. Seeded hematite precipitation at pH 1 and 80 °C yielded 99.6% iron removal with 3.5% nickel and 1.7% copper losses. For the hematite process, nickel and copper losses decreased with an increase in temperature. Increasing the pH yielded higher nickel and copper losses for both processes. All seeded precipitation experiments produced easily filterable precipitates. Unseeded iron phosphate precipitates produced at 40 °C and pH 1 were filterable, but increased nickel and copper losses were observed. Unseeded hematite precipitation resulted in high nickel and copper losses, with the precipitates practically impossible to filter. Iron phosphate precipitates exhibited more favourable settling characteristics than the precipitate produced with the hematite process. [ABSTRACT FROM AUTHOR]

A new iron phosphate, rubidium zinc iron(III) phosphate, RbZnFe(PO4)2, has been synthesized as single crystals by the flux method. This compound is isostructural to the previously reported KCoAl(PO4)2 [Chen et al. (1997). Acta Cry st. C53,1754-1756]. Its structure consists of a three-dimensional framework built up from corner-sharing PO4 and (Zn,Fe)O4 tetrahedra. This mode of linkage forms channels parallel to the [100], [010] and [001] directions in which the Rb+ ions are located. [ABSTRACT FROM AUTHOR]

In the present study, Acidithiobacillus ferrooxidans ( At. ferrooxidans ) culture supernatant was used for phosphate (PO 4 3− ) removal and recovery from source separated urine. The results indicated that the solution pH and ferric ion (Fe 3+ ) concentration influenced the PO 4 3− precipitation. The 5.6 pH was found optimum for PO 4 3− recovery. An increase in Fe 3+ concentration increased PO 4 3− recovery. Recovered iron phosphate (FePO 4 ) was characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). Source separated urine can be a renewable source for phosphate recovery using At. ferrooxidans culture supernatant. This will help in sustainable agricultural development. [ABSTRACT FROM AUTHOR]

An iron phosphate catalyst prepared using the ammonia gel method was supported on silica (CAT 1) and a commercial iron phosphate catalyst was supported on silica using the wet impregnation method (CAT 2). The XRD patterns of both the catalysts showed the presence of quartz-like iron phosphate and a tridymite like phase. In situ XRD under a reducing environment and TPR showed the formation of iron pyrophosphate for both the catalysts at 500 °C. The Mössbauer spectra of the catalysts were similar and showed the presence of the ferric ion only. NH-TPD revealed the presence of Lewis and Brønsted acidic sites on both the catalysts. Oxidative dehydrogenation reactions of methyl iso-burate (MIB) were carried out using a continuous flow fixed bed reactor at contact times of 0.4 and 0.8 s. The conversion of MIB was marginally higher at a contact time of 0.8 s. CAT 2 gave an 11 % yield of methyl methacryalate (MMA) compared to 21 % over CAT 1 at a contact time of 0.8 s. The conversion of MIB increased with co-feeding water. A maximum conversion of MIB (82 %) was obtained at 400 °C, giving a yield of 20 % MMA at a contact time of 0.8 s over CAT 1. However, co-feeding water increased the hydrolysis reaction also, which increased the yield towards iso-butyric acid and methacrylic acid. Graphical Abstract: [ABSTRACT FROM AUTHOR]