Efficient chlorpyrifos removal using alginate-based bionanocomposite hydrogel beads (ALG/Fe3O4@SiO2) in the batch adsorption system.

In this study, magnetic silica nanoparticles (Fe3O4@SiO2) were encapsulated into alginate beads (ALG/Fe3O4@SiO2) to fabricate an efficient, stable, and reusable adsorbent for chlorpyrifos removal. Structural and magnetic characterizations (FT-IR, XRD, UV-Vis, SEM, EDS-mapping, and VSM) confirmed the successful synthesis of the bionanocomposite. Optimization using response surface methodology (RSM) identified the optimal conditions of 44.4 mg/L initial chlorpyrifos concentration, 1.87 g/L adsorbent dosage, and 79.28 min contact time, resulting in the highest removal efficiency. The adsorption process followed the Freundlich isotherm and pseudo-first-order kinetic model, while the Langmuir model estimated a maximum adsorption capacity of 154.2 mg/g. Thermodynamic studies indicated a spontaneous and exothermic process. The adsorbent maintained 74.9 % of its initial efficiency after eight adsorption-desorption cycles, confirming its reusability and stability. Overall, the ALG/Fe3O4@SiO2 hydrogel beads exhibit strong potential as a low-cost and environmentally friendly adsorbent for the treatment of chlorpyrifos-contaminated water.