Magnetic biochar particles prepared by ion cross-linking to remove phosphate from water

Abstract

In this study, the ionic cross-linking method was used to synchronize the granulation and magnetization of biochar powder. A precursor of Ca/Mg modified, tobacco stalk biochar combined with sodium alginate as the functional monomer, CaCl2 solution as the cross-linking agent, and a Fe3O4 magnetic fluid dopant were used to prepare magnetic biochar particles (EMCSB3), which were easy to separate and recover. The adsorption performance of phosphate by these EMCSB3 was explored. The Langmuir model fitted adsorption capacity of phosphate on the EMCSB3 was 8.93 mgP g−1, which was comparable to other materials at the same concentration. The process of phosphate adsorption by magnetic particles followed a pseudo-second-order model, and the adsorption mechanism was chemisorption. EMCSB3 was suitable for use in environments with pH ≤ 8, the best dosage was 6.67 g l−1, and its removal rate was maintained at about 85%. Phosphate adsorption was greatly affected by coexisting CO3 2−. This study provides a technical approach for the granulation and magnetization of powdered biochar and improves its feasibility of use.