Iron sulfide (FeS) nanomaterials exhibit strong reductive activity toward hexavalent chromium (Cr(VI)), but their in-situ application is limited by aggregation, poor subsurface transport, and rapid oxidation. In this study, a novel stabilization strategy was proposed by using carbon dioxide (CO2)-modified silicate to synthesize a silicate-stabilized FeS nanoslurry (SS-nFeS slurry) under near-neutral conditions. During FeS nucleation, the modified silicate promoted the formation of Si-O-Si networks and Si-O-Fe interfacial bonds, enhancing both particle dispersion and redox durability. The optimized SS-nFeS(50%) exhibited a highly negative zeta potential of −48.64 mV and increased the specific surface area from 10.23 m2·g−1 to 45.75 m2·g−1, indicating substantially improved stability and surface accessibility. Under aeration, Fe2+ loss was limited to 17.19%, while the apparent Fe2+ oxidation rate constant decreased from 0.084 to 0.006 min−1 and the half-life increased from 8.30 to 110.03 min, representing a 13.26-fold extension compared with unstabilized FeS. These interfacial advantages enabled near-complete breakthrough within 1–1.5 pore volumes and the formation of a continuous reactive zone in porous media. In Cr(VI)-contaminated soil columns, residual Cr(VI) was uniformly controlled at 1.3–2.6 mg·kg−1 and remained below 3.0 mg·kg−1 throughout 120 days of static aging. Under aqueous batch conditions, SS-nFeS achieved a high removal capacity of 637.24 mg·g−1 and strong tolerance to pH and electrolyte backgrounds. Mechanistic analyses revealed coupled adsorption, Fe2+/S2−-mediated reduction, and silicate-assisted interfacial immobilization of reaction products. A preliminary economic and environmental assessment further suggested improved environmental and economic feasibility, with a global warming potential of 12.06 kg CO2-eq and a 34–57% reduction in treatment cost compared with conventional reductants. This study provides a scalable strategy for in-situ remediation of chromium-contaminated sites.

Due to the ongoing emission of organic pollutants, there is an urgent need to find green and sustainable remediation technologies that also offer economic benefits. Rhizoremediation technology, which achieves pollutant degradation through plant-microbe interactions, has emerged as a highly promising green solution. However, complex soil environments and multiple limiting factors restrict its large-scale application. This review systematically discusses plant-microbial interactions, including allelopathy, co-metabolic degradation, defensive interactions, and microbial recruitment. It focuses on analyzing the rhizosphere microbial degradation mechanisms of four common types of organic pollutants: pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pharmaceuticals and personal care products (PPCPs). For the limiting factors of remediation efficiency, seven enhancement measures are detailed: manure/composting, biochar, surfactants, biofortification, nanomaterials, microbial electrochemical, and genetic modification. Finally, the key challenges and future development directions of each technology in practical applications are explored. This review provides theoretical basis and technical references for the optimization and engineering of rhizosphere remediation technologies.

To overcome membrane permeation selectivity defects and mitigate membrane fouling, a novel nanocomposite, UiO-66-NH2/g-C3N5 (UNCN), was designed and synthesized. Notably, this composite overcomes the inherent limitations of UiO-66-NH2 (limited visible light absorption) and g-C3N5 (low specific surface area). The optimal composite ratio was determined to be 3:7 through systematic optimization. The UNCN-3:7 nanocomposite was then embedded into the polyamide selective layer on polysulfone via in situ interfacial polymerization under optimal conditions, resulting in a thin film nanocomposite (TFN) Nanofiltration membrane. Characterization revealed that the UNCN-3:7 Nanocomposites were uniformly distributed within the polyamide (PA) matrix. The resulting TFN Nanofiltration membrane possessed an ultrathin, positively charged selective layer with enhanced hydrophilicity, evidenced by a reduction in water contact angle from 60.3° to 47.3°. It exhibited a 43

ABSTRACT The corrosion behaviors of austenitic stainless steels 304 and 316 were systematically examined in a 60 wt. % NaOH solution at 240°C under an oxygen partial pressure of 3.2 MPa. After 168h of immersion corrosion, the steady corrosion rates of 304SS and 316SS were determined as 6.60 mm/y and 4.28 mm/y, respectively, with 304SS showing higher corrosion rates under these conditions. Corrosion tests conducted at different durations helped to reveal the migration and transformation patterns of key elements in stainless steel in this aggressive environment. The corrosion mechanism was identified as a multi-stage process. Firstly, during corrosion, a metallic nickel layer forms near the surface, thus preventing the formation of a stable passive protective film. Secondly, chromium (Cr) and molybdenum (Mo) dissolve and convert into their respective soluble products, CrO42− and MoO42−, thereby destroying the integrity of the material. Finally, surface corrosion products tend to crack, leading to delamination and exposure of fresh surfaces to the corrosive medium, therefore accelerating the corrosion process. The investigation results in this work demonstrated the difference in corrosion resistance between 304SS and 316SS, revealing the reasons for the lack of corrosion resistance of stainless steels in oxidative high-concentration alkaline solutions.

Titanium oxide (TiO2) semiconducting materials attracted great interest in photocatalytic degradation of organic pollutants in the treatment of textile wastewater in recent days. The present study focuses on a sol-gel method for synthesizing nano-Fe doped TiO2 photocatalyst, and employs the advanced oxidation technique termed photocatalytic activation of persulfate to degrade azo dye. The degradation performance of targeted degradant acid orange dye (AO7) was analyzed regarding the impacts of PDS concentration, solution pH, and catalyst dose. Results showed that under visible light irradiation, the removal rate of AO7 can reach a peak of 98.40 % within 40 min at an optimal initial concentration of 0.05 g center dot L-1, a pH of 5, a PDS concentration of 4 mM, and a catalyst dosage of 0.4 g center dot L-1, accompanied by a reaction rate constant of 0.1152 min- 1. Moreover, the higher photocatalytic activity of nano-Fe/TiO2 in comparison to pure TiO2 is attributed to a higher specific surface area, smaller crystalline size, reduced band gap (2.54 eV), and increased efficiency for the electron-hole generation according to SEM, XRD, FTIR, XPS and DRS characterization measurements. The nano-Fe/TiO2 photocatalytic efficiency persisted robustly after 4 runs and also had a high activity in degrading Tetracycline. The photocatalytic mechanism revealed that the persulfate radical (center dot SO4 -) and the hole (h+) followed by superoxide radicals (center dot O2- ) played a crucial role in providing a better photocatalytic activity under visible light irradiation. The outcomes demonstrate future possibilities of applying nano-Fe/TiO2 photocatalyst in the treatment of organic pollutants wastewater under visible light.

The Fenton-like process is a highly efficient and widely applied advanced oxidation technology for degrading organic pollutants under dark conditions. However, its development is limited by low H2O2 utilization, incomplete mineralization, and limited optimal pH range. We developed a CoAl-LDH/porous g-C3N4 catalyst via high-temperature thermal polymerization with NH4HCO3 as a dynamic gas template and urea as a precursor. The reaction rate constant of CoAl-LDH/porous g-C3N4-H2O2 system for degradation of Rhodamine B is 0.0199 min-1, which is about 1.58 times that of the CoAl-LDH-H2O2 system. Moreover, the catalyst sustained performance over four cycles and maintained high activity in degrading three different substrates. The high catalytic activity is attributed to the rich porous structure of g-C3N4, the presence of abundant active sites, and the synergistic interaction between the CoAl-LDH and g-C3N4, which promotes the generation of center dot OH, 1O2, center dot O2-, facilitating pollutant degradation. This study highlights the potential of this CoAl-LDH/porous g-C3N4-based Fenton-like system for applications in dye wastewater treatment.

The abnormal level of hypochlorous acid (HOCl) in the human body will cause a series of diseases, and it is of great importance for designing and developing efficient fluorescent probes to detect HOCl. In this work, the fluorescence mechanism of BTMSP, a ratiometric fluorescent probe for detecting HOCl based on the sulfide oxidation reaction, has been studied through theoretical calculations. The optimized geometric configuration and infrared spectroscopy analysis of BTMSP and BTMTP at the ground state and excited state demonstrate that the intramolecular hydrogen bond interaction (O - H center dot center dot center dot N) strengthened, which will facilitate the proton transfer at the excited state. The potential energy curves for BTMSP and BTMTP at the S0, S1 state along the increasing in bond length of O-H were scanned. The frontier molecular orbitals (MOs) and charge density difference (CDD) map, the distribution of electrons and holes were discussed to investigate the charge transfer process. In addition, the calculated emission spectra demonstrates a significant blue shift in the wavelength occurred when BTMSP was oxidized by HOCl, which is consistent with the experimental results. All of the above calculated results indicate the excited state intramolecular proton transfer (ESIPT) process of BTMTP are remain existed, rather than as reported that the ESIPT had been canceled due to the stronger electron-withdrawing of sulfoxide group.

A magnetic and efficient Fe78Si9B13/MnO2 composite was successfully fabricated by a facile hydrothermal method. This composite was employed as a Fenton-like catalyst for the degradation of methyl orange (MO) under activation of H2O2. The phase and morphology of the composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The experimental results reveal that the theoretical mass loading of Fe78Si9B13/MnO2 composite and H2O2 dosage have a significant effect on MO degradation. Fe78Si9B13/MnO2 composite effectively improved MO oxidation ability and could quickly decolorize the MO to 99.7 %. Decolorization efficiency increased with increasing H2O2 concentration from 0 % to 1.15 %. Additionally, a possible reaction mechanism of the coupling system was proposed.

Owing to the growing contamination of waterways by azo dyes, the intermediate chemicals formed when these colors break down in anaerobic settings by microbes are carcinogenic and teratogenic, endangering both human health and the environment. As a result, in the realm of environmental remediation, the best way to remove azo dyes in wastewater has recently become a focus of research. In this work, the target degradant, Acid Orange 7 (AO7), was used to prepare Fe78Si9B13/TiO2 composites for use as photocatalysts hydrothermally. The samples' surface morphology and crystal structure were assessed using fluorescence spectroscopy (PL), UV-visible diffuse reflectance (DRS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). To investigate the effects of varying solution pH, Fe78Si9B13 composite volume, hydrothermal temperature, hydrothermal time, and catalyst dosage on the photocatalytic degradation performance of AO7, a 500 W xenon lamp was employed as a light source to replicate visible light. The findings demonstrated that the composites' highest photocatalytic activity was attained under the following conditions: solution pH = 3.0, visible light irradiation period of 120 min, hydrothermal temperature of 180 degrees C, hydrothermal time of 24 h, Fe78Si9B13 composite volume of 5%, and catalyst dose of 0.8 gL-1. The AO7 solution degraded at a rate of 94.36%, the mineralization rate was 43.71%, and the reaction rate constant was 0.0232 min(-1). A suitable concentration of Fe78Si9B13 composite can decrease the TiO2 forbidden bandwidth, stimulate the absorption of visible light, and impede photogenerated electron-hole complexation. Fe78Si9B13/TiO2, which can be employed as a catalyst for the effective treatment of dye wastewater, is furthermore distinguished by great cyclic stability and high catalytic efficiency. {GRAPHIACAL ABSTRACT}

Chromium oxide (Cr2O3) has wide application in various industries. Its traditional production process, uses sodium carbonate (Na2CO3), which is converted into cheaper byproducts, including sodium sulfate (Na2SO4) and sodium bisulfate (NaHSO4). These byproducts contain hexavalent chromium (Cr(VI)), which can lead to serious environmental pollution. In this work, a cleaner production process for Cr2O3 through the hydrothermal reduction of a sodium chromate (Na2CrO4) aqueous solution with hydrogen (H2) was studied. Nearly single-phase chromium oxide hydroxide (CrOOH) formed as a solid product after the hydrothermal reduction. Then, Cr2O3 was obtained by the thermal decomposition of CrOOH. The advantages of the new process are remarkable. First, the raw material, the Na2CrO4 aqueous solution, was the direct intermediate product in the pressure oxidative leaching of chromite ore with sodium hydroxide (NaOH). Second, the reduction efficiency of Cr(VI) increased up to 97.6%, and the total yield of chromium from Na2CrO4 to Cr2O3 was as high as 94.2%. Finally, 96.6% of sodium could be converted into NaOH, so the aqueous solution in the hydrothermal hydrogen reduction process could be recycled as the leaching agent for the pressure oxidative leaching process of chromite ore. Consequently, a complete cleaner and shorter preparation route from chromite ore to Cr2O3 was achieved by integrating three processes: the pressure oxidative leaching of chromite ore, the hydrothermal reduction of the Na2CrO4 aqueous solution, and the thermal decomposition of CrOOH. The new method achieves the high-efficiency use of chromium resources, cyclic utilization of material, and extremely low environmental pollution of Cr(VI), and well exemplifies the principle of the 3Rs (Reduce, Recycle, Reuse).

To ascertain the influence of prolonged planting on the distribution and accumulation of heavy metals in protected vegetable soil, samples from typical vegetable planting areas in Shenyang were gathered to evaluate the distribution features of Cr, Ni, Cu, Zn, Cd, and Pb in such soil. The Hakanson index, heavy metal risk assessment standard, and secondary phase to primary ratio methods were employed to evaluate the ecological hazard of soil in the research area, while the human health risk model was utilized to evaluate the health of inhabitants. The findings indicated that：① The amount of heavy metals Zn, Cr, Cu, Ni, Pb, and Cd in the topsoil （0~20 cm） of protected vegetable land in the study region decreased successively, and the content of heavy metals in the topsoil increased with the extension of planting years, of which Cd, Zn, and Cu increased most obviously, with maximum increases of 219%, 189%, and 134%, respectively. ② Heavy metals Zn, Cr, Cu, Ni, and Pb were mainly in the residual state, whereas Cd was mainly in the weak acidic state, with a maximum proportion of 53%. ③ The potential ecological risk index of Cd in the topsoil of the study area was 95.77, showing a medium ecological risk； however, the comprehensive potential ecological risk of the six heavy metals was not high. ④ The HI values of the six heavy metals in the study area were less than 1 and the risk of non-carcinogenesis was negligible； however, the carcinogenic risk of heavy metals in some sampling sites should not be ignored.

Chromium hydroxide is an important form present in chromium chemicals and a major product in the reduction of hexavalent chromium pollutants, and the study of chromium hydroxide re-oxidation process is crucial in controlling chromium pollution. The aim of this research was to investigate the re-oxidation performance of different forms of chromium hydroxide in air: crystalline chromium hydroxide (C-Cr(OH)3), amorphous chromium hydroxide (A-Cr(OH)3), chromium hydroxide obtained by reduction (R-Cr(OH)3), and aged R-Cr(OH)3 (Aged-R-Cr(OH)3). The results showed that A-Cr(OH)3 had the highest re-oxidation efficiency and the largest re-oxidation rate constant (k), followed by R-Cr(OH)3, Aged-R-Cr(OH)3, and C-Cr(OH)3. The study found that the re-oxidation rate of chromium hydroxide was mainly affected by the surface Cr–O bond energy and physical water. The advantageous re-oxidation of chromium hydroxide could be attributed to its diminutive bond energy of Cr–O and the presence of physical water on its surface. It was observed that increasing the temperature and adding salt (Na2SO4 and Na2CO4) promoted the re-oxidation of Cr(III) for different chromium hydroxides. This effect was particularly noticeable under alkaline conditions induced by Na2CO3 or at a reaction temperature of 200 °C. The re-oxidation rate constant of chromium hydroxides was up to 39.4 times higher at a reaction temperature of 200 °C than at 80 °C. This would be of great significance for chromium contamination removal by controlling the hexavalent chromium reduction products and environmental conditions.

Owing to the growing contamination of waterways by azo dyes, the intermediate chemicals formed when these colors break down in anaerobic settings by microbes are carcinogenic and teratogenic, endangering both human health and the environment. As a result, in the realm of environmental remediation, the best way to remove azo dyes in wastewater has recently become a focus of research. In this work, the target degradant, Acid Orange 7 (AO7), was used to prepare Fe78Si9B13/TiO2 composites for use as photocatalysts hydrothermally. The samples’ surface morphology and crystal structure were assessed using fluorescence spectroscopy (PL), UV-visible diffuse reflectance (DRS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). To investigate the effects of varying solution pH, Fe78Si9B13 composite volume, hydrothermal temperature, hydrothermal time, and catalyst dosage on the photocatalytic degradation performance of AO7, a 500 W xenon lamp was employed as a light source to replicate visible light. The findings demonstrated that the composites’ highest photocatalytic activity was attained under the following conditions: solution pH = 3.0, visible light irradiation period of 120 min, hydrothermal temperature of 180 °C, hydrothermal time of 24 h, Fe78Si9B13 composite volume of 5

As a heavy metal element with great harm and heavy pollution in soil pollution, chromium (Cr) has posed a great threat to the soil environment and human living environment. Chromium mainly exists in the form of Cr(III) and Cr(VI) in the soil. It is of great significance to reduce Cr(VI) with strong toxicity and easy migration to Cr(III) with low toxicity and low migration. There are a large number of active groups in soil humus, which have a strong affinity with heavy metal ions and play an important role in the reduction of chromium. Humic substances are classified into three categories; however, fewer studies have been carried out simultaneously to investigate the functional groups involved in the reactions of humic acid (HA), fulvic acid (FA), and humic matter (HM) with Cr. In the present study, HA, FA, and HM were used to interact with Cr to investigate the mechanism of humus reduction of Cr(VI). The results showed the reducing ability of humic substances: HA > FA > HM. The functional groups that play a reducing role in humic substances are mainly carboxyl groups, ester groups, phenolic hydroxyl groups, and polysaccharides. The C=O and C-O bonds play a major role in the reduction of humus, but not all C=O and C-O bonds have changed during the reaction. The adsorption-reduction process was mainly carried out on the surface of humic substances, and Cr(III) was mainly adsorbed on humic substances with trace amounts of Cr(VI).

羟基氧化铬(CrOOH)热分解制备氧化铬绿颜料是铬酸盐氢还原法制备氧化铬绿清洁工艺的单元之一.研究表明,CrOOH的结构对其热分解所得氧化铬绿的色度有显著影响,但CrOOH晶体结构对所得氧化铬绿色度的影响尚未有系统研究报道.本工作通过铬酸钠溶液氢还原制备得到了两种晶型的CrOOH并借助化学滴定、傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、扫描电子显微镜(SEM)和热重-差示扫描量热分析(TG-DSC)对其组成、结构、形貌和热分解过程进行了研究.以两种不同晶型的CrOOH为原料调控制备得到了不同色度的氧化铬绿颜料,借助XRD和SEM对其物相和形貌进行了表征,并使用Datacolor110色度仪测定了其色度参数.结果表明,两种CrOOH的晶体结构分别为底心正交和三方,其形貌分别呈现片状和六方片状,组成可分别写作Cr2O3·1.49H2O和Cr2O3·1.12H2O.与三方CrOOH相比,底心正交的CrOOH热分解得到的氧化铬绿颗粒尺寸更小、大小更均匀、颜色更亮更黄.最终,以不同比例的底心正交和三方CrOOH为原料,调控制备得到了多种色调的氧化铬绿颜料.

This study aimed to investigate the effects of pyrolysis temperature (200–700 °C) and duration (2 h, 4 h) on Gleditsia japonica shells (GS) biochar properties. Electrical conductivity (EC), pH, total organic carbon (TOC), total and available nitrogen (TN/AN), phosphorus (TP/AP), potassium (TK/AK), proximate analysis, thermogravimetric analysis (TG), and macroscopic features were performed. The results showed that the effect of carbonization temperature was more significant than duration. The high temperature was conducive to forming more stable biochar. Comparatively, GS biochar obtained at 400 °C for 4 h exhibited high nutritional properties, with the highest AP content of 1193.86 mg kg−1 and relatively high contents for TOC (790.99 g kg−1), TN (10.43 g kg−1), TP (5.16 g kg−1), AN (406.42 mg kg−1) and AK (5438.40 mg kg−1), indicating that GS biochar obtained under certain pyrolysis condition (400 °C for 4 h) is a potential to be employed as soil nutrient amendments.

The vanadium redox flow battery (VRFB) is a promising technology for large-scale stationary energy storage systems. However, the high preparation cost of mixed valent vanadium electrolyte hinders the large-scale commercial application of VRFB. In this work, a simple, green and low-cost method is proposed to prepare the mixed valent vanadium electrolyte for VRFB. The clean hydrogen is chosen as the reducing agent to obtain trivalent vanadium ions from quadrivalent vanadium ions. The Pt/C material is used as the catalyst to accelerate the reduction rate at atmospheric pressure. The impurity-free mixed valent vanadium electrolyte, with a mean valence number of 3.5, prepared by the catalytic reduction process exhibits excellent battery performance with CE of 93% and EE of 85%. Furthermore, a catalytic reactor using Pt/C decorated graphite felt is designed and used to continuously produce the mixed valent vanadium electrolyte. According to the result of simple cost analysis, the proposed catalytic hydrogen reduction process can reduce theoretically the manufacturing cost by approximately 22.6% compared with the present industrial electrolytic process. As a consequence, the simple, clean and low-cost manufacture method of the mixed valent vanadium electrolyte exhibits remarkable competitiveness and promising potential for the practical production application of VRFB.

全钒液流电池是大规模储能领域首选的化学储能技术之一.因电解液成本占比较高,通常采用成本相对较低的五氧化二钒作为原料来制备全钒液流电池电解液.针对五氧化二钒在硫酸中溶解度较小、直接使用硫酸溶解五氧化二钒难以制备出高浓度电解液的问题,本研究通过将硫酸与五氧化二钒进行升温活化处理,水溶后即可实现高浓度五价钒电解液的制备.采用XRD、Raman、FT-IR等手段对活化后固体的组成、结构和溶解过程进行分析.结果表明,在活化温度为180℃、活化时间为3 h、硫酸与五氧化二钒摩尔比为4时,五氧化二钒溶解质量分数高达98.5%,溶解的钒离子浓度高达3 mol·L-1.硫酸与五氧化二钒升温活化后生成V2O3(SO4)2,改变原有的五氧化二钒的结构,导致活化后的物质水溶时溶解性增加,并且溶解后的钒离子价态以V(Ⅴ)形式存在.溶液中高浓度的V(Ⅴ)离子会与SO2-4 络合反应生成VO2SO-4,同时溶液中VO+2 也会发生聚合形成V2O4 +3、V2O2 +4 等多聚体.