Environmentally friendly crab shell waste preparation of magnetic biochar for selective phosphate adsorption: Mechanisms and characterization

Abstract

It is important to address the issues of fishery waste treatment and integrated pollutant removal in environmental remediation. In this study, FeSO4·7H2O was used for the first time to combine with fishery waste crab shells for the preparation of magnetic biochar in a practical and effective manner (FBC600) for the selective adsorption of phosphate. FBC600 was prepared by the one-pot dipping method and the features of its phosphate adsorption were studied. The outcomes demonstrate that pseudo-second-order kinetics and the Langmuir model effectively describe the adsorption process. The maximum adsorption capacity was 149.27 P mg/g. The adsorption capacity of FBC600 at equilibrium was 2.13 times higher than that of unmodified biochar BC. FBC600 is pH-adaptable from 3 to 10 and has excellent anti-interference capabilities. FTIR and XPS investigations revealed that electrostatic adsorption, ion exchange, ligand exchange, and chemical precipitation are the primary processes of FBC600 phosphate adsorption. The P-loaded FBC600 promoted the germination index (GI: 290.17%-314.51%) and root growth (root length: 1.54 cm-2.27 cm) of maize seeds better than other liquid substrates (20 p mg/L, 100 p mg/L). Therefore, P-loaded FBC600 is anticipated to have agricultural use as a phosphate fertilizer for plant growth.