As a highly promising membrane fouling control strategy, nanorod-patterned membranes have been found to exhibit excellent long-term antifouling performance in membrane bioreactors. This study aims to further investigate the effects of long-term application of nanorod-patterned membranes on system performance and microbial community evolution by setting up two parallel MBR systems. The results indicated that the introduction of the patterned membrane had no significant adverse effects on effluent quality or the sludge characteristics within the reactor, while the dehydrogenase activity (DHA) of the mixed liquor in the control MBR (R1) was consistently lower than that in the MBR equipped with the patterned membrane (R2). Microbial community analysis revealed that Bacteroidota, Planctomycetota, Myxococcota, and Bdellovibrionota were enriched exclusively in the later-stage sample from R2 due to the subtle influence of the patterned membrane, with relative abundances of 25.02%, 3.35%, 1.34%, and 1.07%, respectively. At the genus level, the enrichment of Ferruginibacter in R2 could account for the elevated DHA levels. Cluster analysis at the sample level showed that microbial communities from contemporaneous samples exhibited higher similarity, indicating that the use of the patterned membrane was not the dominant factor driving microbial community succession during long-term operation.
Benefiting from low energy consumption, high separation performance, membrane technologies have been widely adopted in wastewater treatment and reuse. However, membrane fouling and the resulting limited membrane lifespan have emerged as the major bottlenecks restricting their widespread development and practical applications. Given these limitations, this review comprehensively summarizes recent advances in external field-assisted membrane separation technologies. Specifically, the effects of various external fields, including magnetic fields, light fields, electric fields, ultrasound, and microbubbles, are systematically discussed. This review systematically compares the antifouling performance of various external field-assisted membrane separation technologies and summarizes the underlying mechanisms responsible for fouling mitigation. In addition, the economic feasibility and key operational parameters are critically evaluated. Finally, the challenges and future research directions of the external field-assisted membrane separation technologies are outlined.
The development of high-performance nanofiltration (NF) membranes is fundamentally limited by the permeability-selectivity trade-off. This study presents a facile and practical strategy to enhance the performance of hyperbranched polyamine (HBPA)-based NF membranes by introducing ethanolamine (MEA) as a reaction regulator. Although MEA alone is incapable of undergoing effective interfacial polymerization (IP) with trimesoyl chloride (TMC), its reactivity can be markedly activated in the presence of reactive amines. Consequently, MEA was incorporated into HBPA and PIP/HBPA systems to regulate the formation of the polyesteramide (PEA) selective layer. The results show that an appropriate amount of MEA can significantly improve water permeability while maintaining high salt rejection. Mechanistic insights reveal that low MEA concentrations facilitate crosslinking, whereas excessive addition leads to the formation of structural defects. The optimized membrane (0.03P+0.3H + 0.01M) exhibits a water permeability of 11.4 L m−2 h−1·bar−1, with Na2SO4 and MgSO4 rejections reaching 96.3% and 96.7%, respectively. Notably, the membrane also demonstrates a relatively high CaCl2 rejection of 83.6%, which is significantly higher than that of the commercial NF270 membrane (43.5%), indicating excellent performance in hardness removal. In addition, the membrane shows good operational stability. This study provides a simple and cost-effective approach for the design of high-performance NF membranes.
Crayfish shell waste, generated in large quantities from the processing of Procambarus clarkii, represents an underutilized biogenic resource rich in chitin, chitosan precursors, calcium carbonate, proteins, pigments, and naturally doped heteroatoms. Its conversion into functional materials provides a promising route for waste valorization, although the environmental and economic advantages of different strategies still require critical evaluation. This review summarizes recent progress in the extraction, conversion, modification, and application of crayfish shell-derived materials, with emphasis on the links between processing routes, material structures, interfacial mechanisms, and practical performance. Conventional acid–alkali extraction, deep eutectic solvent-assisted methods, enzymatic hydrolysis, microbial fermentation, pyrolysis, and activation strategies are compared in terms of efficiency, product quality, scalability, and environmental trade-offs. Functionalization approaches, including heteroatom self-doping, metal or metal oxide coupling, magnetic modification, and hierarchical porous structure construction, are discussed in relation to specific application scenarios. Particular attention is given to micro-interfacial mechanisms governing pollutant removal and catalytic reactions, such as precipitation, ion exchange, surface complexation, electrostatic interaction, hydrogen bonding, π–π interaction, redox transformation, electron transfer, and reactive oxygen species generation. Current applications span water and soil remediation, adsorption, catalysis, energy storage, food packaging, sensing, bioactive compounds, and biomedical materials. Finally, key challenges are identified, including feedstock heterogeneity, seasonal supply, storage-related degradation, contaminant risks, limited life-cycle and techno-economic assessments, insufficient comparison with other crustacean wastes, and regulatory barriers. This review highlights knowledge gaps and future directions for advancing crayfish shell waste from laboratory-scale valorization toward and scalable functional materials.
Efficient application of solar energy offers a promising strategy to address water scarcity and the global energy crisis. Solar-driven interfacial evaporation (SDIE) can realize localized photothermal conversion, which enhances energy harvesting efficiency. Semiconductor-based photothermal materials are ideal candidates for the advanced SDIE systems, providing advantages such as excellent thermal stability and tunable bandgap structures. However, the fundamental mechanisms, the key factors, and the applications in the water-energy nexus have not been sufficiently summarized. This review systematically presents the recent advances in semiconductor-based solar evaporators. The photothermal conversion mechanisms were elucidated and compared with those of conventional photothermal materials. Additionally, the design strategies for semiconductor-based evaporators were comprehensively summarized. Based on the analysis of the structure, composition, and wettability of semiconductor-based solar evaporators, the influences of the physicochemical properties on the light absorption, water evaporation rate, and photothermal conversion efficiency were revealed. The practical applications of semiconductor-based evaporators at the water-energy nexus, including desalination, hydrogen production, electricity generation, contaminant removal, and lithium extraction, were discussed. Finally, a detailed outlook on the challenges and future research directions was provided to enhance the solar evaporator performance.
Metal-loaded biochars, due to their excellent peroxymonosulfate (PMS) activation capabilities, have been widely applied in water remediation. However, the effects of different transition metal loadings on the physicochemical properties of biochar, as well as the similarities and differences in active sites and reactive species in various metal-loaded biochar/PMS systems, remain unclear. In this study, five biochars doped with common transition metals (Biochar-Fe, Biochar-Mn, Biochar-Ni, Biochar-Co, and Biochar-Cu) were successfully synthesized. The results showed that Biochar-Co possessed the largest pore structure and specific surface area, exhibiting the best catalytic performance mainly by activating PMS to generate sulfate radicals (SO4•−). Hydroxyl radicals (•OH) were the dominant reactive species in the Biochar-Fe, Biochar-Mn, and Biochar-Ni systems, while singlet oxygen (1O2) dominated in the Biochar-Cu system, attributed to its strong electron transfer ability and higher consumption of graphitic N and carbonyl groups (C=O). Density functional theory (DFT) calculations of adsorption energy, O–O bond length, charge density difference, and bader charge effectively validated the experimental observations. The toxicity of the intermediate degradation products and the degradation pathways of sulfamethoxazole (SMX) varied among the different transition metal-loaded biochar/PMS systems. This study provides in-depth insights into the regulatory mechanisms of different transition metal doping on biochar catalytic performance, offering theoretical guidance and practical reference for designing efficient PMS-activating catalysts and treating recalcitrant organic pollutants.
Polyamide (PA) thin-film composite nanofiltration (NF) membranes are widely used in water treatment, yet the strongly coupled relationships among pore structure, crosslinking density, surface charge, and hydrophilicity of the PA selective layer hinder the simultaneous improvement of permeance, selectivity, and anti-scaling stability. Herein, we developed a facile hot sulfuric acid (SA) post-treatment strategy to tailor the PA selective layer of commercial NF270 membranes. Treatment with 20 wt% H2SO4 at 60°C promoted acid-catalyzed hydrolysis and chain rearrangement in the PA network, generating ionizable oxygen-containing groups, strengthening the surface negative charge, enhancing hydrophilicity, and moderately enlarging effective transport channels. The resulting membrane (NFM-SA60) exhibited a water permeance approximately 1.84 times that of the pristine membrane while maintaining favorable Na2SO4 and dissolved organic carbon rejections. In addition, NFM-SA60 showed a markedly reduced flux decline and a flux recovery ratio of 92% after three CaSO4 scaling-cleaning cycles, far exceeding those of the pristine and reference membranes. The improved anti-scaling behavior was attributed to the strengthened hydration layer and intensified electrostatic repulsion, which jointly suppressed Ca2+/SO42- adsorption and heterogeneous nucleation on the membrane surface. This work provides a simple and scalable acid-thermal post-treatment route for regulating PA NF selective layers and offers mechanistic insights into balancing permeance, selectivity, and long-term anti-scaling stability in advanced water treatment.
This study focuses on synthesizing a polymer film from waste plastic bags blended with Polyvinyl alcohol (PVA) and its efficiency in adsorbing acenaphthene from water solutions. Single-use plastic was blended with the PVA particles, which were further polymerized to prepare the film. Different parameters were varied to investigate their effects on the removal of acenaphthene. The result of the batch study inferred that the highest removal obtained from plastic blended PVA films was 87.45%, which is significantly higher than the normal PVA films, which only adsorb 75% of acenaphthene in optimized conditions. From the result of ATR-FTIR analysis, it could be predicted that the presence of –OH,–CH–OH, and –CH2 enhances the adsorption efficiency of plastic blended PVA films significantly. From the SEM images, it was observed that the plastic particles were properly combined with the PVA membrane, increasing their hydrophobic characteristics and enhancing their affinity towards non-polar pollutants like acenaphthene.
The co-existence of nanoplastics (NPs) and natural organic matter (NOM) in aquatic environments forms complex composite pollutants that severely accelerate membrane fouling and impair separation performance. In this study, an electrically conductive carbon nanotube/PEDOT/PVDF (CPP) composite membrane was fabricated via vacuum filtration and interfacial crosslinking to achieve simultaneous pollutant removal and fouling mitigation. The conductive network significantly enhanced membrane surface polarity under external negative potential. Under an external cathodic voltage of −2.0 V, the CPP membranes demonstrated notable synchronous separation performance during filtration of polystyrene (PS, 20–100 nm) and humic acid (HA) mixtures. Compared to open-circuit conditions, the applied negative potential boosted PS removal efficiency and achieved a stable HA removal rate. Meanwhile, the CPP membrane under external potential significantly suppressed flux decline, maintaining a high final normalized flux of 0.65–0.85. Fouling modeling analysis revealed that cake layer formation remained the dominant fouling mechanism and the external potential effectively inhibited foulant accumulation and promoted a looser deposition layer. This performance enhancement is governed by a multi-faceted electrically driven mechanism comprising enhanced electrostatic repulsion, electrophoretic migration of charged species, and induced electroosmotic flow within the membrane pores. Overall, this electrically enhanced filtration strategy offers an effective approach for treating natural surface water impacted by NPs composite fouling.
Membrane fouling is a critical challenge in the long-term operation of anaerobic membrane bioreactors (AnMBRs), and cathodic electroactive dynamic membranes have been proposed as an effective mitigation strategy. In this study, the fouling mitigation mechanism was investigated by comparing an AnMBR with a cathodic electroactive dynamic membrane (AnEDMBR) to a conventional anaerobic dynamic membrane bioreactor (AnDMBR). The AnEDMBR exhibited an approximately 33% reduction in fouling rate relative to the control. This improvement was primarily attributed to selective pressure imposed on membrane-associated microorganisms via local potential modulation, which suppressed highly adhesive species and enriched anaerobic fermentative bacteria. This shift accelerated organic matter degradation and reduced the accumulation of bioavailable carbon. The microbial response induced structural reorganization of extracellular polymeric substances (EPS): the protein content declined significantly, lowering the protein-to-polysaccharide ratio and promoting the formation of a loosely packed, low-aggregation biofilm layer that weakened sludge cohesion. Concurrently, a decrease in membrane zeta potential enhanced electrostatic repulsion and inhibited tight microbial adhesion. Furthermore, a more positive anode and more negative cathode potential facilitated redox reactions and EPS restructuring. Collectively, these effects demonstrate that the cathodic electroactive membrane mitigates fouling through a multi-level mechanism of “electrochemical modulation—microbial response—EPS restructuring—fouling suppression”, providing mechanistic insight and a theoretical basis for the efficient operation of AnMBRs.
Sulfamethoxazole (SMX), a widely detected sulfonamide antibiotic in aquatic and terrestrial environments, poses long-term ecological risks due to its persistence and potential to induce antibiotic resistance. Adsorption onto carbonaceous materials has been widely applied for controlling the migration and environmental fate of antibiotics in soil-water systems. In natural environments, carbonaceous materials frequently interact with mineral phases, forming mineral-carbon associations that can significantly influence adsorption behavior. However, the combined effects of material properties and environmental conditions on antibiotic adsorption remain difficult to quantify using conventional mechanistic approaches. In this study, eight types of mineral-modified activated carbons were prepared by loading four typical minerals (montmorillonite, kaolinite, quartz sand, and hematite) at 5% and 10% mass fractions. The structural parameters of the synthesized samples ranged within 0.14 < Vmicro < 0.23 cm3/g, 0.44 < Vmeso < 0.61 cm3/g, and 734.4 < SBET < 966.3 m2/g. An interpretable machine learning (IML) workflow integrating batch adsorption experiments with Bayesian optimization-assisted CatBoost (BO-CatBoost) modeling was developed. The model incorporated six key input variables: material structural parameters (SBET, Vmeso, Vmicro) and operating conditions (adsorption time, initial pH, stirring speed). Evaluated through a rigorous 7-fold group cross-validation combined with independent external validation, the optimized BO-CatBoost model achieved robust predictive accuracy, yielding an R2 of 0.8153 on the test set and 0.5799 on the external validation set. SHAP analysis revealed that operational conditions exerted a more dominant influence on SMX adsorption efficiency than intrinsic pore-structure descriptors. Partial dependence analysis further identified nonlinear interactions and synergistic regimes among key variables, elucidating the coupled effects of mass-transfer limitations and material properties. Overall, this study provides mechanistic insights into the adsorption behavior of antibiotics on mineral-carbon composite systems and demonstrates the potential of IML for guiding the rational design and optimization of adsorbents for emerging contaminant control in complex environmental media.
Permanganate (PM) oxidation is a promising advanced oxidation process for water purification. Metal-free carbocatalysts can effectively activate PM for water purification, while the active sites and mechanisms, particularly the role of three-dimensional porous structures, remain controversial and unclear. This study fabricates nitrogen-doped graphene aerogels (NGAs) with tailored surface and porous structures to activate PM for para-hydroxybenzoic acid (p-HBA) oxidation. Two distinct activation pathways are identified: Hydrothermal NGA with abundant oxygen-containing groups primarily decomposes PM to manganese dioxide (MnO2), which subsequently acts as the co-catalyst to activate PM via an indirect electron transfer pathway (ETP). In contrast, pyrolyzed NGA900 with higher specific surface area (SSA) and conductivity mainly serves as an electron shuttle to mediate direct ETP from p-HBA to PM. Furthermore, the hierarchical porous structure is crucial for providing mass transfer channels and anchoring sites for nascent MnO2, preventing active site blockage and ensuring excellent reusability and adaptability across a wide pH range and common water constituents. This work reveals the critical factors in PM activation by engineered carbocatalysts, highlighting the significance of porous structure engineering alongside surface chemistry.
A mild immersion-based route was developed to immobilize silver orthophosphate (Ag3PO4) as a continuous surface layer on calcium phosphate hardened bodies derived from α-tricalcium phosphate (α-TCP, α-Ca3(PO4)2) and poly(acrylic acid) solution. The hardened bodies, composed predominantly of dicalcium phosphate dihydrate with residual α-TCP, functioned simultaneously as scaffold and phosphate reservoir, enabling Ag3PO4 formation by surface precipitation in 0.10 mol·L-1 AgNO3 at room temperature. X-ray diffraction confirmed the crystalline phases, while scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy demonstrated uniform Ag3PO4 coverage on the surface. The analysis also revealed a surface Ag:P ratio of approximately 3:1. In parallel, inductively coupled plasma–atomic emission spectroscopy showed ∼98% Ag+ uptake accompanied by Ca2+ release. Diffuse reflectance spectroscopy with Tauc plot analysis yielded a direct band gap of ∼2.4 eV, consistent with visible-light responsiveness. Under weak blue LED irradiation (470 nm, 5.6 mW·cm-2), methylene blue degradation followed pseudo-first-order kinetics with k = 0.23–0.33 h-1, comparable to reported Ag3PO4 coatings. Post-irradiation diffraction patterns revealed metallic silver, evidencing photoreduction. This simple strategy transforms readily available cement-type substrates into Ag3PO4-functionalized bulk materials with effective visible-light photocatalytic performance. It thus offers a versatile route for environmental applications, while antibacterial applications remain a prospective direction for future investigation beyond conventional methods restricted to conductive substrates.
Cu-based catalysts have attracted considerable attention for the electrocatalytic reduction of CO2 owing to their potential to produce value-added products. However, achieving high selectivity toward specific products and long-term stability at high current densities still remains challenging over Cu-based catalysts. Herein, highly selective and durable Sn-doped CuOx catalysts (R-SnCuOx) were synthesized via distributed preparation and in situ reconstruction for reduction of CO2 to CO. At cathodic reduction potentials, Sn doping stabilizes the Cu(I) active center through electronic regulation, thereby enhancing the reduction resistance of R-SnCuOx. R-SnCuOx with optimized Sn loading of 7.2 wt% achieved a maximum CO Faradaic efficiency around 97.5% and a CO partial current density of 296 mA cm-2 in a membrane electrode assembly. Furthermore, it still maintained over 90% CO selectivity after 16 h at 150 mA cm-2. Mechanistic studies indicate that incorporation of Sn modulates the surface electronic configuration of Cu2O, concomitantly lowering the rate-determining step activation energy barrier and intensifying the CO-generation kinetics in CO2 electroreduction. Meanwhile, techno-economic assessment studies on the economic feasibility of the reduction of CO2 to CO indicate that industrial-scale production is achievable by optimizing carbon single-pass conversion and current density. This study provides valuable insights for realizing the industrial application of electrocatalytic CO2 reduction to CO.
The interfacial polymerization behavior of polyamide (PA) separation layers is largely constrained by the physicochemical characteristics of the aqueous-organic interface. While previous studies have employed additives (e.g., surfactants) to reduce interfacial tension, most strategies focus on isolated tuning of macroscopic physical parameters, lacking systematic intervention in diffusion pathways, miscible zone structures, and reaction thermodynamics. This study introduced N-butylpyrrolidone (NBP), a novel green interfacial regulator featuring a balanced polar-nonpolar amphiphilic structure. By enhancing interfacial affinity and modulating interfacial tension, it optimized the transport pathways and enrichment behavior of monomers at the interface. Combined molecular dynamics simulations and experimental characterization revealed that trace-level incorporation of NBP expands the miscible zone from 8 Å to 15 Å. It also reduced the diffusion energy barrier for M-phenylenediamine, increasing its interfacial diffusion coefficient by nearly 30-fold. This synergistic modulation induced a morphological transition of the PA layer from a nodular structure to a multilayer leaf-like architecture. The resulting reverse osmosis (RO) membrane achieved a high water flux of 93.11 L·m–2·h–1, while maintaining NaCl rejection above 96%. This work demonstrated that NBP enables simultaneous regulation of interfacial thermodynamics and reaction kinetics at minimal dosage, offering a sustainable strategy for developing high-performance, environmentally friendly RO membranes.
The development of highly stable noble metal-free catalysts is essential for the practical implementation of VOCs catalytic techniques, with recent trends focusing on perovskite materials despite concerns about their low reactivity of surface oxygen species and challenges in regenerating active oxygen sites. In this work, CeO2 nano-islands were in-situ grown on LaMnO3 (LMO) to prepare the CeO2-LaMnO3 catalyst (such as LCMO-5). This catalyst exhibits excellent performance in toluene oxidation, with a T90 of 247°C. The superior performance stems from unique Ce-O-Mn bridging structures between CeO2 nanoislands and the LMO matrix. This structure can activate lattice oxygen and promote the activation of gaseous oxygen, achieving a dynamic cycle. DFT calculations reveal the electronic-level mechanism involves accelerated electron transfer at the Ce-O-Mn interface, optimized interfacial electronic structure through upshifted Mn 3d and O 2p band centers approaching the Fermi level, and substantially reduced oxygen vacancy formation energy at interfacial sites from 4.31 eV to 2.34 eV. This work provides fundamental insights into lattice oxygen activation mechanisms in perovskite catalysts and establishes a theoretical framework for designing highly efficient and stable environmental catalytic materials.
The rapid development of industrial civilization has increased the global demand for energy, which is mainly met through the widespread use of fossil fuels, bringing a prosperous lifestyle but also posing severe environmental challenges. Large-scale carbon dioxide emissions are a major factor in the greenhouse effect and energy crisis, posing a threat to ecosystems and global climate stability. The electrocatalytic carbon dioxide reduction reaction (CO2RR), powered by renewable energy, offers a potential solution by converting carbon dioxide into high-value chemicals. However, developing efficient catalysts still faces challenges. The limitations of single-atom catalysts (SACs) have driven growing interest in diatomic catalysts, which can overcome the limitations of SACs by increasing metal loading and dual active sites. Despite challenges in synthesis complexity and precise control, diatomic catalysts hold the promise of more efficient and controllable reduction of carbon dioxide. This review systematically summarizes the applications of diatomic catalysts in recent years, providing inspiration for researchers in the synthesis and application of carbon dioxide emission reduction.
Photocatalytic hydrogen peroxide (H2O2) production offers a sustainable alternative to the energy-intensive anthraquinone process. While metal oxides are promising catalysts, Al2O3 is typically limited by its wide bandgap, insulating nature, and poor solar light absorption. This work introduces oxygen vacancies into mesoporous Al2O3 via a facile NaBH4 thermal treatment to dramatically enhance its photocatalytic performance. The defective Al2O3 demonstrated excellent photocatalytic activity in both tetracycline degradation and H2O2 production. The optimized mesoporous Al2O3-0.2, achieves an exceptional H2O2 production rate of 2866 μmol g−1 h−1 under AM 1.5G, which is ∼2 times higher than that of pristine Al2O3. Comprehensive characterizations including density functional theory (DFT) calculations confirm the successful formation of oxygen vacancies, and the defect state reduces the bandgap from 5.27 to 3.49 eV, shifts the conduction band to a more negative potential (−0.81 V), and significantly improves charge separation and electron transfer efficiency. Mechanistic studies reveal that the reaction proceeds primarily via an oxygen reduction reaction (ORR) pathway, with superoxide radicals (·O2−) acting as crucial intermediates. This study demonstrates that oxygen vacancy engineering is a highly effective strategy for activating wide-bandgap metal oxides like Al2O3 for efficient solar-driven H2O2 photosynthesis.
In this investigation, we sought to develop Cu/Ag/Ru trimetallic nanoparticles (TNPs) utilizing leaf extracts from the Nyctanthes arbor-tristis plant, known for its anti-inflammatory, antioxidant, and therapeutic properties. We employed various techniques for the synthesis and characterization of the TNPs, which included UV-vis spectroscopy, FT-IR, SEM, EDAX, XRD, AFM, and TGA. The UV-visible spectra were obtained from 200 to 400 nm, while FT-IR spectroscopy helped confirm the interactions between the metals and the phytochemical compounds present in the plant. The nanoparticles' morphology exhibited differences between the Ag and Cu components, with the Ru nanoparticles showcasing a distinct hexagonal shape, ranging from 30 to 50 nm. This was supported by a combination of SEM, XRD, AFM, XPS, TEM, and DLS analyses. We determined the average size of the TNPs to be 45nm, and XPS analysis confirmed the binding energy values. The antibacterial effectiveness of the TNPs was significant against multiple bacterial strains, and they also showed notable anticancer activity against MCF cells at a concentration of 680.05 ± 0.5 μg/mL, with the antioxidant activity measured using the DPPH assay (IC50 = 100 μg/mL). Furthermore, the TNPs demonstrated excellent photocatalytic activity against methylene blue in a photoreactor.
Arsenic contamination of aquatic systems poses a serious global threat to environmental safety and public health due to its high toxicity, persistence, and complex aqueous speciation. Conventional arsenic removal technologies often suffer from limited selectivity, high operational cost, and low efficiency, particularly for As(III). Metal-organic frameworks (MOFs) have recently attracted significant attention as advanced adsorbents for arsenic remediation owing to their high surface area, tunable pore structure, and versatile coordination chemistry. This review presents a critical and systematic evaluation of MOFs for sustainable aquatic arsenic remediation. After summarizing arsenic speciation and the limitations of conventional treatment methods, arsenic-specific removal mechanisms in MOFs—including electrostatic interaction, inner-sphere coordination, ligand exchange, and redox-assisted As(III) oxidation—are analyzed. The performance of different MOF families, including Zr-, Fe-, Zn-, Al-based, and mixed-metal frameworks, is comparatively assessed in terms of adsorption efficiency, stability, pH tolerance, and regeneration behavior. Emphasis is placed on elucidating structure–performance relationships rather than cataloging individual studies. Finally, remaining challenges related to cost, scalability, and real-water applicability are discussed, and future research directions are proposed to facilitate the practical implementation of MOF-based arsenic remediation technologies.
