Adsorption of Cd(II) onto Auricularia auricula spent substrate biochar modified by CS2: Characteristics, mechanism and application in wastewater treatment

Biochar is a promising adsorbent used to remove heavy metals from wastewater. In order to improve its performance in adsorption, the biochar derived from Auricularia auricula spent substrate (BC), was further modified by carbon disulfide (CS 2 ), and the characteristics and mechanism of the modified biochar (SBC) for Cd(II) adsorption were investigated. CS 2 modification induced sulfur (S)-containing groups onto SBC and increased S content by 9%. In batch adsorption experiments, the adsorption rate ( R ) and adsorption capacity ( q ) of SBC reached to 96.1% and 9.61 mg/g respectively, which were significantly greater than those of BC. Cd(II) was precipitated in the form of CdS, CdSO 3 and CdSO 4 in the presence of SBC. The adsorption was a spontaneous and endothermic reaction with the q max of 450.51 mg/g. The q 0 of 6.29 mg/g was achieved under the breakthrough time of 90 min and exhaustion time of 1140 min. During three adsorption-desorption cycles, SBC presented a favorable recyclability with the desorption rate increased from 69.51% to 99.12% with EDTA as eluent. SBC also performed perfectly in actual electroplating wastewater treatment . • Sulfur-containing functional groups were induced onto biochar after CS 2 modification. • Cd(II)was precipitated in the form of CdS, CdSO 3 and CdSO 4 . • Cd(II) biosorption onto SBC was an endothermic and spontaneous process with q max of 458.35 mg/g. • Cd(II) biosorption onto SBC in fixed-bed column fitted well to Thomas model. • SBC exhibited good performance in the treatment of real electroplating wastewater.