A promising hierarchical nanocomposite of MIL-53(Al)/ZnO was synthesized as a visible-light-driven photocatalyst to investigate the degradation of amoxicillin (AMX). MIL-53(Al)/ZnO ultrafine nanoparticles were obtained by preparing Zn-free MIL-53Al and employing it as a reactive template under hydrothermal and chemical conditions. The synthesized nanocomposite (MIL-53(Al)/ZnO) has a low content of Al > 1.5% with significantly different characterizations of the parent compounds elucidated by various analyses such as SEM, TEM, XRD, EDX, and UV–Vis. The effect of operational parameters (catalyst dose (0.2–1.0 g/L), solution pH (3–11), and initial AMX concentration (10–90 mg/L)) on the AMX removal efficiency was studied and optimized by the response surface methodology. A reasonable goodness-of-fit between the expected and experimental values was confirmed with correlation coefficient (R²) equal to 0.96. Under the optimal values, i.e., initial AMX concentration = 10 mg/L, solution pH ~ 4.5, and catalyst dose = 1.0 g/L, 100% AMX removal was achieved after reaction time = 60 min. The degradation mechanism and oxidation pathway were vigorously examined. The AMX degradation ratios slightly decreased after five consecutive cycles (from 78.19 to 62.05%), revealing the high reusability of MIL-53(Al)/ZnO. The AMX removal ratio was improved with enhancers in order ( $${\mathrm{IO}}_{4}^{-}$$IO 4 - > H₂O₂ > S₂O₈⁻²). The results proved that 94.12 and 98.23% reduction of COD were obtained after 60 and 75 min, respectively. The amortization and operating costs were estimated at 3.3 $/m³ for a large-scale photocatalytic system.

The photo-thermal activation of persulfate (PS) was carried out to degrade various pollutants such as reactive blue-222 (RB-222) dye, sulfamethazine, and atrazine. Optimizing the operating parameters showed that using 0.90 g/L of PS at pH 7, temperature of 90 °C, initial dye concentration of 21.60 mg/L, and reaction time of 120 min could attain a removal efficiency of 99.30%. The degradation mechanism was explored indicating that hydroxyl and sulfate radicals were the prevailing reactive species. The degradation percentages of 10 mg/L of sulfamethazine and atrazine were 83.30% and 70.60%, respectively, whereas the mineralization ratio was 63.50% in the case of real textile wastewater under the optimal conditions at a reaction time of 120 min. The treatment cost per 1 m³ of real wastewater was appraised to be 1.13 $/m³ which assured the inexpensiveness of the proposed treatment system. This study presents an effective and low-cost treatment system that can be implemented on an industrial scale.

Costs of water treatment can be reduced significantly if the spent adsorbents can be reused or regenerated.‏ In this study, two residuals of iron adsorbed onto low-cost activated carbon (Fe-MCAC and Fe-MLAC) are reused as new adsorbents for the removal of ciprofloxacin (CIP) from pharmaceuticals wastewater. The residuals were characterized by SEM, XRD, FTIR, Raman spectra, N2-adsorption desorption. The adsorption mechanisms, performance, kinetics, isotherm, thermodynamic and reusability of residuals for CIP removal were evaluated. The isotherm data was well defined by Freundlich model for both adsorbents (residuals). Moreover, the CIP adsorption follows the pseudo-second-order kinetic model. The maximum adsorption capacity of CIP on Fe-MCAC and Fe-MLAC was 476.19 and 416.67 mg/g, respectively. The maximum removal of CIP was obtained at pH 7 for both new adsorbents. The optimum contact time was found to be 30 min and 60 min for Fe-MCAC and FE-MLAC, respectively. The values of free energy change and enthalpy change for adsorption of CIP indicated the spontaneous, endothermic nature of the adsorption. In addition, the adsorption process was assisted by increasing randomness due to the value of entropy change. Therefore, the residuals of iron adsorption onto activated carbons could be reused as new low-cost adsorbents for antibiotics removal from wastewater.

In this study, the removal of phosphate (PO₄⁻) from wastewater using glauconite was investigated. Glauconite was characterized by N₂ adsorption-desorption isotherm, SEM, EDX, and FTIR analysis. The effects of contact time, pH, initial phosphate concentrations, adsorbent dose, and temperature were investigated by batch experiments. The isotherms, kinetics and thermodynamics for phosphate removal were studied. The results showed that glauconite had rough surface and abundant pores. The determined BET surface area was 55 m²/g with pore radius of 1.99 nm and the pore volume was 0.032 cm³/g. FTIR analysis revealed that the abundance various functional groups on the surface of glauconite may play an important role for the adsorption process. The optimum pH was 11 with complete removal of phosphate in a short time (nearly 1 min). The experimental data fitted very well with Langmuir isotherm (R² = 0.999) with maximum adsorption capacity of 32.26 mg/g at 50 °C. Adsorption kinetic data were best fitted with the pseudo-second-order kinetic model (R² = 0.999). Thermodynamic study confirmed the spontaneity, endothermic and irreversible adsorption process. Therefore, Glauconite is a promising natural low cost adsorbent for phosphate removal from wastewater.