Arsenic contamination in groundwater is a significant public health concern, with As(III) posing a greater and more challenging risk than As(V) due to its higher toxicity, mobility, and weaker adsorption affinity. Fe-Mn-based adsorbents offer a promising solution, simultaneously oxidizing As(III) to As(V), enhancing its adsorption. This study evaluates an Fe-Mn nanocomposite across typical batch (20 mg of adsorbent), fixed-bed column (28 g), and pilot-scale (2.5 kg) studies, bridging the gap between laboratory and real-world applications. Batch experiments yielded maximum adsorption capacities of 6.25 mg/g and 4.71 mg/g in a synthetic matrix and real groundwater, respectively, demonstrating the impact of the water matrix on adsorption. Operational constraints and competing anions led to a lower capacity in the pilot (0.551 mg/g). Good agreement was observed between the breakthrough curves in the pilot (breakthrough at 475 bed volumes) and the fixed-bed column studies (365–587 bed volumes) under similar empty bed contact times (EBCTs). The Thomas, Adams–Bohart, and Yoon–Nelson models demonstrated that lower flow rates and extended EBCTs significantly enhance arsenic removal efficiency, prolonging the operational lifespan. Our findings demonstrate the necessity of continuous-flow experiments using real contaminated water sources and the importance of optimizing flow conditions, EBCTs, and pre-treatment in order to successfully scale up Fe-Mn-based adsorbents for sustainable arsenic removal.

Global concern over arsenic contamination in drinking water necessitates innovative and sustainable remediation technologies. This study evaluates the adsorption performance of Fe–Mn binary oxide (FMBO) nanocomposites developed by coating polyethylene (PE) and polyethylene terephthalate (PET) with FMBO for the removal of As(III) and As(V) from water. Adsorption kinetics were rapid, with equilibrium achieved within 1–4 h depending on the material and pH. PET-FMBO and FMBO exhibited faster rates and higher arsenic removal (up to 96%) than PE-FMBO. Maximum As(III) adsorption capacities ranged from 4.76 to 5.75 mg/g for PE-FMBO, 7.2 to 12.0 mg/g for PET-FMBO, and up to 20.8 mg/g for FMBO, while capacities for As(V) ranged from 5.20 to 5.60 mg/g, 7.63 to 18.4 mg/g, and up to 46.2 mg/g, respectively. The results of the Dubinin–Radushkevich isotherm model, with free energy (E_a) values exceeding 16 kJ/mol, suggest chemisorption is the dominant mechanism, which is supported by the kinetics data. Given the effective removal of As(III), chemisorption likely proceeds through ligand exchange during the Mn oxide-mediated oxidation of As(III) and complexation with hydroxyl groups on the nanocomposite. These findings highlight the strong potential of Fe–Mn polymer nanocomposites, particularly PET-FMBO, for efficient arsenic removal during practical water treatment applications.

Diclofenac (DCF) and metformin (MET) are pharmaceuticals often detected in influents and effluents of municipal sewage treatment plants and surface waters which may cause adverse effects to human health and the environment. In recent years, advanced oxidation processes (AOPs) have been demonstrated to be effective technology for the removal of many organic pollutants. The objective of this study was to evaluate the removal and toxicity of investigated pharmaceuticals by UV and UV/H₂O₂ processes. UV irradiation was provided by a Pen Ray lamp emission at 254 nm which was covered with a quartz tube and placed in the middle of the reactor. Experimental conditions of the process were: [DIC, MET] = 10 mg/L, [H₂O₂] = 2.5 mM, reaction time 3 h. Results obtained by only UV exposition of solution showed that diclofenac and metformin were degradated 30% and 50% during 3 h test. Addition of 2.5 mM H₂O₂ to photo reactor contributed to 90% and 100% removal of DCF and MET, respectively. Inhibition toxicity test of MET increased in the following range: 13% (C0) < 38% (UV) < 77% (UV/ H₂O₂), while toxicity measured for DCF solutions followed the range: 33% (UV) < 75% (C0) < 78% (UV/H₂O₂). The results confirmed that addition of hydrogen-peroxide accelerated the removal of investigated pharmaceuticals, but at the same time, lead to formation of the more toxic intermediates. The possible reason for better removal efficiency of metformin can be related to its simpler aliphatic structure in comparison to more aromatic diclofenac.

Arsenic contamination in groundwater is a significant public health concern, with As(III) posing a greater and more challenging risk than As(V), due to its higher toxicity, mobility, and weaker adsorption affinity. Fe-Mn-based adsorbents offer a promising solution, simultaneously oxidizing As(III) to As(V), enhancing its adsorption. This study evaluates an Fe-Mn nanocomposite across typical batch (20 mg of adsorbent), fixed-bed column (28 g) and pilot-scale (2.5 kg) studies, bridging the gap between laboratory and real-world applications. Batch experiments yielded maximum adsorption capacities of 6.25 mg/g and 4.71 mg/g in synthetic and real groundwater respectively, demonstrating the impact of water matrix on adsorption. Operational constraints and competing anions lead to a lower capacity at the pilot (0.551 mg/g). Good agreement was obtained by the breakthrough curves at the pilot (breakthrough at 475 Bed Volumes) and the fixed-bed column studies (365–587 Bed Volumes) under similar empty bed contact times (EBCT). The Thomas, Adams-Bohart, and Yoon-Nelson models demonstrated that lower flow rates and extended EBCT significantly enhance arsenic removal efficiency, prolonging operational lifespan. Our findings demonstrate the necessity of continuous-flow experiments using real contaminated water sources, and the importance of optimising flow conditions, EBCT and pre-treatment, in order to successfully scale up Fe-Mn-based adsorbents for sustainable arsenic removal.