Sb Removal Research Articles

Different fates of the coexisting Sb(V) and nitrate in sulfur autotrophic bioreactor mediated by internal circulation: Performance and mechanism

The sulfur autotrophic bioreactor with internal circulation was established for the simultaneous and effective removal of antimonate (Sb(V)) and nitrate (NO3−) in water for the first time. At the hydraulic retention time (HRT) of 8 h and the recycle ratio (R) of 5, the removal efficiency of Sb(V) and TSb reached up to 98.14 % and 96.89 % with a concentration of 10 mg/L Sb(V) in the influent. Although the shortening of HRT and the increase of R inhibited the removal of Sb(V) and TSb, there was little effect on the NO3− removal (> 97.08 % with the influent of 20 mg-N/L). Meanwhile, the measured concentration of sulfate (SO42−) and alkalinity consumption in effluent were both greater than theoretical value, indicating the occurrence of S0 disproportionation in bioreactor. The shortened HRT and declined R reduced alkalinity consumption, which hindered S0 disproportionation. The precipitates were collected at end of bioreactor operation period, which was confirmed to be Sb2S3 by SEM-EDS, Raman, XRD and XPS analysis. High-throughput sequencing results indicated that Proteobacteria and Bacteroidetes were the dominant bacteria at phylum level for denitrification. Besides, Sulfuriferula, Thiovirga and Sulfuricurvum (at genus level) might be accountable for bio-reduction of NO3− and Sb(V), as well as S0 disproportionation.

Mechanisms and valorization of selective adsorption of Sb(III) by amino-functionalized lignin-based porous biochar

Antimony contamination in aquatic environment raises tremendous concerns for human health and ecosystem safety, while there is a lack of methods for efficient and selective adsorption of antimony. In this study, an adsorbent for trivalent antimony (Sb(III)) removal is obtained by cross-linking polyethyleneimine (PEI) onto phosphoric acid-modified lignin-based porous biochar (PPLB). PPLB exhibits efficient adsorption of Sb(III) with a maximum value of 371.7 mg/g, which is also highly selective as the Sb(III) removal capability by PPLB remains unaffected under the common co-existing anions (Cl-, NO3–, PO43-, and CO32–) and less affected with the co-existing cations (Cd2+, Zn2+, Cu2+, and Pb2+). Such a performance is validated in three simulated Sb(III)-contaminated water bodies (Zijiang River water, industrial wastewater, and mining area water). Understanding of the adsorption mechanisms is further established via density functional theory calculations, revealing the dominant adsorption site of Sb(III) on PPLB is –NH- groups. It’s finally concluded that the removal of Sb(III) by PPLB is governed by complexation, with also the contribution from ligand exchange and hydrogen bonding. As a proof of concept, the spent PPLB adsorbed with Sb(III) is valorized into an active material of sodium ion battery, demonstrating a specific capacity of 192.4 mA h/g for 1000 cycles with a good long-term stability.

Antimony removal using zero-valent iron-manganese bimetallic nanomaterial: Adsorption behavior and mechanism

Although the effectiveness of zero-valent iron (ZVI) and zero-valent manganese (ZVMn) in heavy metal removal is well-established, their combined synergistic potential for antimony (Sb) remediation from wastewater has remained largely unexplored. Addressing this gap, this study introduced a magnetic zero-valent iron-manganese bimetallic material (ZVIM), synthesized via the borohydride reduction method, to investigate its capabilities and underlying mechanisms for Sb reduction and adsorption. The ZVIM, characterized by a high specific surface area of 220 m²/g, exhibited a high adsorption capacity (614.6 mg/g for Sb(III) and 241.7 mg/g for Sb(V)), facilitating over 96.7 % removal for both Sb(III) and Sb(V). The adsorption conformed to the pseudo-second-order kinetic model, and the isotherm data aligned with the Freundlich model, indicative of a heterogeneous adsorption process. The removal of Sb(III) predominantly occurred via surface complexation and electrostatic adsorption to the positively charged ZVIM surface, accompanied by a partial oxidation of Sb(III) to Sb(V). In contrast, the elimination of Sb(V) was primarily facilitated through surface complexation mechanism, encompassing both reduction and electrostatic adsorption. The outcomes of this study shed light on the intricate interactions between Sb species and the ZVIM, revealing the material as a promising candidate for the efficacious removal of Sb from wastewater.

The Sustainable Remediation of Antimony(III)-Contaminated Water Using Iron and Manganese-Modified Graphene Oxide–Chitosan Composites: A Comparative Study of Kinetic and Isotherm Models

This study introduces a series of Fe/Mn-GOCS composites using high-temperature impregnation with graphene oxide and chitosan as substrates, modified by diverse manganese salts, including MnCl2∙4H2O, KMnO4, and MnSO4. Among these, FeCl2/MnSO4-GOCS demonstrated the highest adsorption capacity for Sb(III), peaking at 57.69 mg/g. The adsorption performance was extensively evaluated under various conditions, such as different initial concentrations, pH levels, solid–liquid ratios, and adsorption durations. It was observed that when the Fe/Mn molar ratio exceeded 4:1, there was a notable decrease in both the adsorption capacity and removal rate. Kinetic analyses using the pseudo-second-order model revealed a better fit (R2 > 0.99) compared to the pseudo-first-order model, indicating that chemisorption dominated the adsorption process. Additionally, isothermal modeling highlighted the efficiency of Fe/Mn-GOCS, particularly in high-concentration environments, with the Sips model demonstrating the best fit, integrating characteristics of both Langmuir and Freundlich models. These results not only offer a robust theoretical and practical basis for efficient Sb(III) removal but also underscore the potential of multi-metal-modified adsorbents as sustainable solutions for environmental remediation.

Deep removal of Sn, Pb, and Sb in refined indium by vacuum distillation

To deeply separate the azeotropic impurities from the refined indium, three novel processes of vacuum distillation by considering the variables of vacuum pressure, loading mass, distillation time, temperature, and the effective vacuum evaporation area are firstly presented. Thermodynamic calculations show that Pb, Sb and Sn can be separated from indium melt by vacuum distillation due to their great difference in saturated vapor pressure and separation coefficient. Experiments show that distillation at 800 ℃ for 7 h under a pressure of 10−3 Pa could achieve the Pb concentration of 0.004 ppm in indium melt by enlarging the evaporation area and small ratio of h1/h4. After 950 ℃ distillation, the concentrations of Sb and Sn in the condensing indium reduced respectively from 0.15 ppm to 0.009 ppm, and 8.1 ppm to 0.05 ppm. Multiple processes of vacuum distillation were used to achieve the 7 N purity of indium, with the removal ratio of over 99.5 %. Besides, it is found out that when the temperature dropped from 1075 ℃ to 780 ℃, the movement stroke of vapor atoms reduced from 509 mm to 209 mm.

Advancing Antimony(III) Adsorption: Impact of Varied Manganese Oxide Modifications on Iron-Graphene Oxide-Chitosan Composites.

Antimony (Sb) is one of the most concerning toxic metals globally, making the study of methods for efficiently removing Sb(III) from water increasingly urgent. This study uses graphene oxide and chitosan as the matrix (GOCS), modifying them with FeCl2 and four MnOx to form iron-manganese oxide (FM/GC) at a Fe/Mn molar ratio of 4:1. FM/GC quaternary composite microspheres are prepared, showing that FM/GC obtained from different MnOx exhibits significant differences in the ability to remove Sb(III) from neutral solutions. The order of Sb(III) removal effectiveness is MnSO4 > KMnO4 > MnCl2 > MnO2. The composite microspheres obtained by modifying GOCS with FeCl2 and MnSO4 are selected for further batch experiments and characterization tests to analyze the factors and mechanisms influencing Sb(III) removal. The results show that the adsorption capacity of Sb(III) decreases with increasing pH and solid-liquid ratio, and gradually increases with the initial concentration and reaction time. The Langmuir model fitting indicates that the maximum adsorption capacity of Sb(III) is 178.89 mg/g. The adsorption mechanism involves the oxidation of the Mn-O group, which converts Sb(III) in water into Sb(V). This is followed by ligand exchange and complex formation with O-H in FeO(OH) groups, and further interactions with C-OH, C-O, O-H, and other functional groups in GOCS.

Fast and efficient remediation of antimony-contaminated surface water and field soil using alumina supported Fe–Mn binary oxide

Antimony (Sb) pollution in surface water and soil has earned extensive attention. Our previous study synthesized a new class of alumina supported Fe–Mn binary oxide (Fe–Mn@Al2O3) and found that MnO2 in the composite oxidized Sb(III) to Sb(V) and FeOOH and Al2O3 played an indispensable role in adsorption of Sb(III) and Sb(V). This study further explored the removal of Sb in surface water and in situ sequestration of Sb in Sb-contaminated field soil via Fe–Mn@Al2O3. Sb removal from water was pH independent and the removal efficiencies of Sb(III) and total Sb kept constant at 95.4% and 60.5%, respectively, over a pH range of 5.0–10.0. Increasing dissolved organic matter (DOM) from 0 to 22.8 mg/L had negligible effect on Sb(III) removal whereas inhibited the total Sb removal from 60.5% to 51.2%. Dissolved oxygen cannot oxidize aqueous Sb(III), yet, enhanced the Sb(III) removal whereas decreased the total Sb removal. The composite performed well in natural surface water with high DOM and inorganic ligands. In addition, the composite effectively immobilized Sb in field soil. 5% of the composite significantly inhibited the H2SO4 and HNO3 leachable Sb by 93.6% after 30 d. The amendment transformed the Sb speciation from more easily available fractions (i.e., exchangeable, carbonate-bound, and Fe–Mn oxides-bound species) into more stable fractions (i.e., organic material bound and residual species), leading to declined Sb bioaccessibility and reduced environmental risk. The composite facilitated a long-term stability of Sb in soil. The study demonstrated an easy, fast, and effective strategy for efficient immobilization of Sb in water and soil.

Study on the adsorption efficiency and mechanism of Sb(V) in aqueous solutions using enhanced surfactant-modified iron-calcium composite

The presence of Sb(V) in aqueous solutions poses a significant threat to the surrounding environment, and current treatment methods are inadequate. In this study, a magnetic surfactant (CTAB)-modified iron-calcium composite (CTAB-IC) was successfully synthesized using iron-calcium composite as the base material. This novel composite was used for the efficient removal of Sb(V) from textile wastewater solutions. Characterization analyses revealed that the CTAB-IC material exhibits a rich long-prismatic structure and superparamagnetic properties, classifying it as a soft magnetic material. Post-adsorption particle agglomerates were found to comprise Ca, S, and O. Sequential batch experiments demonstrated a maximum adsorption capacity of 54.05 mg/g, with adsorption kinetics data fitting the pseudo-second-order model. The intraparticle diffusion model indicated the presence of multiple diffusion steps during the adsorption process. Additionally, the adsorption of Sb(V) by CTAB-IC was identified as a heterogeneous surface adsorption process, best described by the Freundlich model. The primary adsorption mechanisms involved the formation of surface Ca-O-Sb complexes and inner-sphere Fe-O-Sb complexes, as well as amorphous surface precipitation and electrostatic adsorption. Notably, the treatment of textile wastewater often results in iron-calcium-rich sludge, which is challenging to manage and valorize. This study explored the potential for resource recycling by utilizing CTAB to harness the Fe elements in textile wastewater sludge, thereby promoting waste-to-resource conversion.

An organic visible-photocatalytic-adsorbence mechanism to high-efficient removal of heavy metal antimony ions

Purification of emerging heavy metal antimony contaminated water based on advanced ingenious strategies. An activated modified coconut shell charcoal (CSC) was synthesized and evaluated as a substrate-supported loaded organic photovoltaic material, PM6:PYIT:PM6-b-PYIT, to prepare a surprisingly highly efficient, stable, environmentally friendly, and recyclable organic photocatalyst (CSC–N–P.P.P), which showed excellent effects on the simultaneous removal of Sb(III) and Sb(V). The removal efficiency of CSC-N-P.P.P on Sb(Ⅲ) and Sb(V) reached an amazing 99.9% in quite a short duration of 15 min. At the same time, under ppb level and indoor visible light (∼1 W m−2), it can be treated to meet the drinking water standards set by the European Union and the U.S. National Environmental Protection Agency in 5 min, and even after 25 cycles of recycling, the efficiency is still maintained at about 80%, in addition to the removal of As (III), Cd (II), Cr (VI), and Pb (II) can also be realized. The catalyst not only solves the problems of low reuse rate, difficult structure adjustment and high energy consumption of traditional photocatalysts but also has strong applicability and practical significance. The pioneering approach provides a much-needed solution strategy for removing highly toxic heavy metal antimony pollution from the environment.

Efficient Sb(Ⅲ) removal from printing and dyeing wastewater using TiCl4 as a potential coagulant instead of polyferric sulfate

With increasing health concerns and the tightening of discharge standards, there is growing demand for more efficient Sb(Ⅲ) removal from printing and dyeing wastewater (PDW). Currently, the most common coagulant used in Sb removal in industry is polyferric sulfate (PFS). However, the residual Fe ions in the effluent cause colorimetric problems and irreversibly damage the membrane components during the subsequent reverse osmosis treatment process. Therefore, identifying novel coagulants to replace PFS in the removal of Sb(Ⅲ) is necessary. In this study, TiCl4 was employed for in-situ hydrolysis to produce flocs for Sb(Ⅲ) removal in simulated and real PDW. TiCl4 exhibited an excellent performance compared to PFS in terms of dosage, turbidity, application pH, and anti-interference properties. Sb(Ⅲ) removal of 97.3 % was realized at a dosage of 30 mg/L and a final pH of 5.0 in slightly contaminated PDW, whereas PFS required a higher dosage, resulting in higher disposal costs. Furthermore, the application of TiCl4 led to lower turbidity and reduced secondary contamination. An investigation of the co-existing ions revealed that TiCl4 was considerably more tolerant than PFS toward PO43–, humic acid, and silicate at a lower concentration. Simultaneously, Sb(Ⅲ) was partially oxidised to Sb(Ⅴ) during removal, but TiCl4 exhibited lower oxidative properties. The results of PDW treatment indicated that TiCl4 could realize 85.6 % Sb(Ⅲ) removal at a dosage of 30 mg/L, and the pre-reduction of Sb(Ⅴ) to Sb(Ⅲ) was a safe, effective treatment. The results of zeta potential measurements and X-ray photoelectron spectroscopy revealed that Sb(Ⅲ) removal was mainly realised via chemical adsorption. Overall, this study provides a promising alternative material for use in practical Sb(Ⅲ) removal from PDW, particularly for reducing coagulation sludge, operational costs, and damage during the possible subsequent reverse osmosis process.

Effect of Sulfate and Acid Orange 7 on Sb(V) Removal by Anaerobic Granular Sludge: Role of Granular Activated Carbon

Effect of Sulfate and Acid Orange 7 on Sb(V) Removal by Anaerobic Granular Sludge: Role of Granular Activated Carbon

Efficient removal of Sb(III) from wastewater using selenium nanoparticles synthesized by Psidium guajava plant extract.

Antimony (Sb) pollution in aquatic ecosystems has emerged as a critical environmental issue on a global scale, emphasizing the urgent need for cost-effective and user-friendly technologies to remove Sb compounds from water sources. In this study, a novel adsorbent, selenium nanoparticles (SeNPs), was synthesized using the aqueous extract of Psidium guajava L. leaves (AEP) for the purpose of eliminating Sb(III) from aqueous solutions. The biosynthesized SeNPs was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence spectrometer (XRF), Fourier Transform-Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis techniques. Additionally, the removal efficiency of the SeNPs for Sb(III) was systematic investigated under the effects of SeNPs dose, temperature, pH and re-usability. The results of this study showed that the adsorption data fitted well into pseudo-second order model, while the Sips modeling demonstrated a high adsorption capacity (62.7mg/g) of SeNPs for Sb(III) ions at 303.15K from aqueous solution. The exothermic enthalpy change of - 22.59kJ/mol and negative Gibbs free energy change assured the viability of the adsorption process under the considered temperature conditions. Surface functional groups on SeNPs like carboxyl, amide, hydroxyl, carbonyl, and methylene significantly facilitate the adsorption processes. Furthermore, the removal efficiencies of Sb in the two actual Sb mine wastewater samples were remarkably high, achieving nearly to 100% with 1.5g/L SeNPs within 48h. This outcome underscores the potential of SeNPs as a highly promising solution for efficiently remediating Sb from aquatic environments, owing to their cost-effectiveness, ease of regeneration, and rapid uptake capabilities.

Efficient adsorptive removal of Sb(Ⅲ) and Sb(V) from printing and dyeing wastewater by TiCl4

Significant amounts of Sb(III) and Sb(V) are present in printing and dyeing wastewater (PDW), which leads to the detrimental effects on the environment if not treated properly. In this paper, the adsorptive removal of Sb(III) and Sb(V) by TiCl4 derived flocs and the oxidation process were investigated. The results showed that TiCl4 conducted superior coagulation performance on Sb(III) removal than Sb(V) in terms of dosage, pH range and immunity to interference. When the dosage was 50 mg/L and the final pH was 5.0, the concentration of Sb(III) and Sb(V) was reduced from 2000 μg/L to 100 μg/L and 180 μg/L, respectively. According to the Langmuir model, The adsorption for Sb(III) (74.27 mg/g) by TiCl4 derived flocs was higher than Sb(V) (68.45 mg/g). The Sb(III) in the solution could partially inhibit the adsorption of Sb(V). It was also observed that the Sb(III) was oxidized to Sb(V), which was owing to the molecular oxygen during the coagulation and the flocs might act as catalyst. The actual printing and dyeing wastewater treatment experiments results showed that pre-reduction of Sb(V) to Sb(Ⅲ) could considerably improve the total Sb removal from 83 % to 98.8 %. The characterization results, such as zeta potential and x-ray photoelectron spectroscopy (XPS), indicated that the Sb(Ⅲ) removal was mainly achieved by chemisorption. The Sb(V) removal was mainly dependent on chemisorption and electrostatic adsorption, while the latter contributed more than former. The results of DFT calculations explained the reason for higher removal efficiencies of Sb(III) than Sb(V) in the TiCl4 coagulation system. This study provides a new idea for the efficient removal of Sb(III) and Sb(V) using TiCl4 in PDW to save the cost in engineering practice.

Facile synthesis of Bi3O(OH)(AsO4)2 and simultaneous photocatalytic oxidation and adsorption of Sb(III) from wastewater

Antimony (Sb) decontamination in water is necessary owing to the worsening pollution which seriously threatens human life safety. Designing bismuth-based photocatalysts with hydroxyls have attracted growing interest because of the broad bandgap and enhanced separation efficiency of photogenerated electron/hole pairs. Until now, the available photocatalysis information regarding bismuth-based photocatalysts with hydroxyls has remained scarce and the contemporary report has been largely limited to Bi3O(OH)(PO4)2 (BOHP). Herein, Bi3O(OH)(AsO4)2 (BOHAs), a novel ultraviolet photocatalyst, was fabricated via the co-precipitation method for the first time, and developed to simultaneous photocatalytic oxidation and adsorption of Sb(III). The rate constant of Sb(III) removal by the BOHAs was 32.4, 3.0, and 4.3 times higher than those of BiAsO4, BOHP, and TiO2, respectively, indicating that the introduction of hydroxyls could increase the removal of Sb(III). Additionally, the crucial operational parameters affecting the adsorption performance (catalyst dosage, concentration, pH, and common anions) were investigated. The BOHAs maintained 85% antimony decontamination of the initial yield after five successive cycles of photocatalysis. The Sb(III) removal involved photocatalytic oxidation of adsorbed Sb(III) and subsequent adsorption of the yielded Sb(V). With the acquired knowledge, we successfully applied the photocatalyst for antimony removal from industrial wastewater. In addition, BOHAs could also be powerful photocatalysts in the photodegradation of organic pollutants studies of which are ongoing. It reveals an effective strategy for synthesizing bismuth-based photocatalysts with hydroxyls and enhancing pollutants’ decontamination.

Removal of Antimony from Industrial Crude Arsenic by Vacuum Sublimation: Combination of Thermodynamics and Ab Initio Molecular Dynamics

Thermodynamic theory was employed in this study to investigate the feasibility of separating antimony (Sb) from crude arsenic (As) using vacuum sublimation. Ab initio molecular dynamics simulations are used to calculate the structure, stability, and diffusion properties of AsmSbn (m + n ≤ 6) clusters. As4, As3Sb, As2Sb2, and AsSb3 are the possible clusters in this thermodynamic calculation, and the molecular dynamics results confirmed their structural stability and stabilization in the gas phase. As4 had the largest diffusion coefficients, which is the reason it separates from the Sb-containing clusters (As3Sb, As2Sb2, and AsSb3) during gas-phase diffusion and condensation processes. The experimental results show that As vapor was transformed from crystalline to amorphous with increasing subcooling, and the Sb-containing clusters that enter the gas phase were mainly condensed and deposited at the proximal end of the heating zone. Not considering the volatilization rate, the removal rate of Sb in products can reach 99.35% by increasing the condensation disk and expanding the condensation zone; thus, experiments confirmed that industrial crude arsenic can realize deep Sb removal after vacuum sublimation.

Adsorptive Removal of Sb(V) from Wastewater by Pseudo-Boehmite: Performance and Mechanism

With the increasing concern about antimony (Sb) pollution and remediation in aquatic ecosystems, more and more feasible technologies have been developed. Adsorption has been extensively studied due to the simplicity of its operation and its minimal environmental effects, but the lack of cheap and stable adsorbents has limited its application in Sb treatment. In this study, pseudo-boehmite (PB) was successfully synthesized via aluminum isopropylate hydrolysis, and its potential for removing Sb(V) from wastewater was explored. The removal efficiency of Sb(V) was 92.50%, and the maximum adsorption capacity was 75.25 mg/g under optimal conditions (pH 5.0, 2 g·L−1 PB, and 10 mg·L−1 Sb(V)). In addition, better performance could be obtained at acidic conditions (pH 3.0–5.0). Surface complexation, electrostatic attraction, and hydrogen bonding were identified as potential major processes for Sb(V) elimination by PB based on experimental and characterization data. This study presents a promising approach for the efficient removal of Sb(V) from wastewater, offering a new insight into the application of aluminum-based materials for heavy metal removal.

Efficacy and mechanism of enhanced Sb(V) removal from textile wastewater using ferric flocs in aerobic biological treatment

Antimony contamination from textile industries has been a global environmental concern and the existing treatment technologies could not reduce Sb(V) to meet the discharge standards. To overcome this shortcoming, ferric flocs were introduced to expedite the biological process for enhanced Sb(V) removal in wastewater treatment plant (WWTP). For this purpose, a series of laboratorial-scale sequential batch reactor activated sludge processes (SBRs) were applied for Sb(V) removal with varied reactor conditions and the transformation of Fe and Sb in SBR system was investigated. Results showed a significant improvement in Sb(V) removal and the 20 mg L−1 d−1 iron ions dosage and iron loss rate was found to be only 15.2%. The influent Sb(V) concentration ranging 153–612 μg L−1 was reduced to below 50 μg L−1, and the maximum Sb(V) removal rate of the enhanced system reached about 94.3%. Furthermore, it exhibited high stability of Sb(V) removal in the face of antimonate load, Fe strike and matrix change of wastewater. Sludge total Sb determination and capacity calculation revealed decreasing in Sb adsorption capacity and desorption without fresh Fe dosage. While sludge morphology analysis demonstrated the aging and crystallization of iron hydroxides. These results verify the distinct effects of fresh iron addition and iron aging on Sb(V) removal. High-throughput gene pyrosequencing results showed that the iron addition changed microbial mechanisms and effect Fe oxidized bacterial quantity, indicating Sb(V) immobilization achieved by microbial synergistic iron oxidation. The present study successfully established a simple and efficient method for Sb(V) removal during biological treatment, and the modification of biological process by iron supplement could provide insights for real textile wastewater treatment.

The removal of Sb from mine wastewater using biosynthesized Fe-Mn nanoparticles: Function and mechanism

Antimony (Sb) in mine wastewater poses a serious threat to surrounding ecosystems. In this study, biosynthesized iron-manganese nanoparticles (Fe-Mn NPs) were devised to remove Sb species. The resultant removal efficiencies were 100% for Sb(III) and 82.6% for Sb(V) utilizing a Sb(III) and Sb(V) concentration of 1 mg·L−1. To understand the removal process, Fe-Mn NPs before and after exposure to Sb species were characterized by various advanced techniques, which indicated that while both Sb(III) and Sb(V) were adsorbed onto the surface of Fe-Mn NPs, Sb(III) was also partly oxidized to Sb(V). Furthermore, removal of both Sb(III) and Sb(V) followed pseudo-second-order kinetics and best fit the Freundlich adsorption isotherm model, suggesting that the removal process involved non-homogeneous chemisorption. These studies provided the evidence for an adsorption and oxidation mechanism for Sb(III) removal and an adsorption-dominated mechanism for Sb(V) removal by Fe-Mn NPs. When the produced Fe-Mn NPs were applied to remove Sb from mine wastewater, 92.7% removal was attained, demonstrating the significant practical potential of these nanoparticles to Sb species from mine wastewaters. This study provides novel insights for future exploration for Sb removal from mine wastewaters.

Enhanced Sb(V) removal of sulfate-rich wastewater by anaerobic granular sludge assisted with Fe/C amendment

Antimony (Sb) and sulfate are two common pollutants in Sb mine drainage and Sb-containing textile wastewater. In this paper, it was found that iron‑carbon (Fe/C) enhanced Sb(V) removal from sulfate-rich wastewater by anaerobic granular sludge (AnGS). Sulfate inhibited Sb(V) removal (S + Sb, k = 0.101), while Fe/C alleviated the inhibition and increased Sb(V) removal rate by 2.3 times (Fe/C + S + Sb, k = 0.236). Fe/C could promote the removal of Sb(III), and Sb(III) content decreased significantly after 8 h. Meanwhile, Fe/C enhanced the removal of sulfate. The 3D-EEM spectrum of supernatant in Fe/C + S + Sb group (at 24 h) showed that Fe/C stimulated the production of soluble microbial products (SMP) in wastewater. SMP alleviated the inhibition of sulfate, promoting AnGS to reduce Sb(V). Sb(V) could be reduced to Sb(III) both by AnGS and sulfides produced from sulfate reduction. Further analysis of extracellular polymeric substances (EPS) and AnGS showed that Fe/C increased the adsorbed Sb(V) in EPS and the c-type cytochrome content in AnGS, which may be beneficial for Sb(V) removal. Sb(V) reduction in Fe/C + S + Sb group may be related to the genus Acinetobacter, while in Sb group, several bacteria may be involved in Sb(V) reduction, such as Acinetobacter, Pseudomonas and Corynebacterium. This study provided insights into Fe/C-enhanced Sb(V) removal from sulfate-rich wastewater.

Facile Preparation of Magnetic Chitosan Carbon Based on Recycling of Iron Sludge for Sb(III) Removal

In this study, following the concept of “treating waste with waste”, magnetic chitosan carbon (MCC) was developed through the pyrolysis of chitosan/iron sludge (CHS) beads created using an embedding method in a closed environment for antimony removal. The results indicate MCC has a good magnetic recovery rate and that its magnetic saturation strength can reach 33.243 emu/g. The iron proportion and acid resistance of MCC were all better than those of CHS, and at 25 °C, its adsorption saturation capacity improved from 24.956 mg/g to 38.234 mg/g. MCC has a quick adsorption equilibrium time, and in about 20 min, 90% of the final equilibrium capacity can be achieved. The primary mechanism of Sb adsorption by MCC is the formation of an inner sphere complex between Fe-O and Sb, while surface complexation, hydrogen bonding, and interaction also play a function. Thus, MCC, a lower-cost and greener adsorbent for Sb removal, has been made using iron sludge. This enabled it to utilize iron sludge as a resource and served as a reference for the sustainable management of water treatment residuals.