Journal: Bioresource Technology

Author: Kwangsuk Yoon, Dong-Wan Cho, Daniel C.W. Tsang, Nanthi Bolan, Jörg Rinklebe, Hocheol Song

Abstract: 

An engineered biochar was fabricated via paper mill sludge pyrolysis under CO₂ atmosphere, and its adsorption capability for As(V) and Cd(II) in aqueous solution was evaluated in a batch mode. The characterization results revealed that the biochar had the structure of complex aggregates containing solid minerals (FeO, Fe₃O₄ and CaCO₃) and graphitic carbon. Adsorption studies were carried out covering various parameters including pH effect, contact time, initial concentrations, competitive ions, and desorption. The adsorption of As(V) and Cd(II) reached apparent equilibrium at 180 min, and followed the pseudo-second-order kinetics. The highest equilibrium uptakes of As(V) and Cd(II) were 22.8 and 41.6 mg g⁻¹, respectively. The adsorption isotherms were better described by Redlich-Peterson model. The decrease in As(V) adsorption was apparent with the increase in PO₄³⁻ concentration, and a similar inhibition effect was observed for Cd(II) adsorption with Ni(II) ion. The feasibility of regeneration was demonstrated through desorption by NaOH or HCl.

Keywords: Paper mill sludge, Magnetic biochar, Arsenic, Cadmium, Adsorption

DOI: https://doi.org/10.1016/j.biortech.2017.07.020