Green synthesis of Fe3O4@SiO2@Salg particles for organophosphorus pesticides removal: Mechanisms, biosafety, and application

A biosafe magnetic Fe3O4@SiO2@Salg (GMS) was successfully developed via a simple and economic method. Fe3O4@SiO2 particles were selected as the magnetic core, and they directly interacted with sodium alginate, thus mitigating the use of cross-linking agents. The microstructure, properties, and formation mechanism of GMS were examined using FE-SEM, TEM, VSM, TGA, zeta potential, and FT-IR. The as-developed GMS was used as a desirable adsorbent to remove organophosphorus pesticides (OPPs) from water bodies, and the influence of different factors on the removal efficiencies of OPPs was investigated. Optimal preparation conditions were determined, and the excellent removal efficiencies of the 18 OPPs were achieved in this study (80.5%–100% for tap, river, and seawater). After the GMS was recycled eight times, the removal efficiencies of 18 OPPs were maintained at >80%. Adsorption kinetics and isotherm models showed that the adsorption process was accurately fitted with the Langmuir isotherm and pseudo-second-order models. The values of ΔG, ΔH, and ΔS were negative, indicating that the OPPs were adsorbed on the GMS spontaneously via an exothermal reaction, and chemisorption was the dominant adsorption mechanism. Overall, the as-developed GMS was biosafe as revealed by cytotoxicity experiments. GMS had good environmental security, stability, and reusability, and it exhibited excellent potential for removing OPPs from aqueous solutions without causing secondary pollution.