Utilization of Macadamia Nutshell Residue for the Synthesis of Magnetic Activated Carbon toward Zinc (II) Ion Removal
Minh-Trung Dao, Thi-Phuong-Linh Tran, Duc-Thuong Vo, Van‐Kieu Nguyen, Le-Thuy-Thuy-Trang Hoang
Abstract
In this study, macadamia nutshell residue, a prevalent leftover and green agricultural waste in Vietnam, was utilized to prepare a magnetic activated carbon adsorbent. The obtained material was characterized by its surface functionalities, elemental composition, crystalline structure, and magnetic properties. The characterization results revealed that the composite comprised Fe 3 O 4 nanoparticles attached to the carbon matrix. The saturation magnetization ( M s ) of the composite was found to be 38.2 emu g −1 , indicating a convenient separation of the solid adsorbent from aqueous media using an external magnetic field. The feasibility of removing zinc (II) ion from an aqueous solution of the activated carbon/Fe 3 O 4 (AC/Fe 3 O 4 ) composite was examined. The adsorption kinetics were best explained by the Elovich model and the pseudo‐second‐order model. The adsorption capacity at equilibrium and the initial rate of Zn 2+ adsorption determined by the pseudo‐second‐order model were 22.73 mg g −1 and 4.18 mg g −1 min −1 , respectively. The implications of this study are that a low‐cost, green, and magnetically separable material prepared by a large‐scale available solid waste can be a promising adsorbent for the elimination of heavy metals.