Study on the Cd (II) adsorption of biochar based carbon fertilizer

In this study, the biochar-based infiltration urea fertilizer (BIUF) was prepared by the infiltration technology. The urea slow-release performance and Cd (II) adsorption ability of BIUF were investigated. Compared with urea, the slow release rate of BIUF was obvious decreased during urea release process. Moreover, the equilibrium adsorption capacity of the BIUF reached 14.24 mg/g, which was 1.73 times of that of biochar. The Cd (Ⅱ) adsorption fits the pseudo-second order model better, which indicated that the chemical adsorption dominated. The O-containing and N-containing functional groups had a great contribution to Cd (II) adsorption. The NH4+ increased the occurrence rate of ion exchange reaction. The present study indicated that the BIUF had the potential of Cd (II) adsorption and urea slow release. [Display omitted] •A slow-release fertilizer was applied to absorb the cadmium in aqueous solution.•The Cd(Ⅱ) adsorption capacity of slow-release fertilizer was 14.24 mg/g.•The chemical deposition was dominantly adsorption mechanisms.