Effectiveness of different biochar in aqueous zinc removal: Correlation with physicochemical characteristics
Nguyễn Văn Hiền, Eugenia Valsami‐Jones, Nguyen Cong Vinh, Tong Thi Phu, Nguyễn Thị Thanh Tâm, Iseult Lynch
Abstract
Bochar from typical Vietnamese biomass residues (acacia wood chip, rice husk, bamboo) were assessed for application in remediation of metal-contaminated water. The biochar physical (e.g., surface area, morphology) and chemical (e.g. surface functional groups, proximate and elemental analysis) characteristics were correlated with their effectiveness in removing zinc (Zn2+). The impact of biochar dose, contact time, and initial adsorbate concentration were investigated to determine the adsorption capacity of the biochar for Zn2+. All three effectively remove Zn2+ from aqueous solution, with bamboo biochar especially efficient (removal of 96–98% Zn2+ from 40 to 80 mg/L). Maximum adsorptions were 7.62, 4.02, and 3.82 mg Zn2+/L for bamboo, wood, and rice husk biochar, respectively. The Freundlich model fit the adsorption of Zn2+, and a pseudo-second order model described the adsorption kinetics. Adsorption was governed by chelation with biochar organic groups (-COOH, -OH−) and precipitation onto inorganic groups (CO32−, PO42−), not ion exchange.