The rectorite/carbon composites: Fabrication, modification and adsorption.

The rectorite (REC)/carbon composites (RECCs) were prepared with hydrothermal carbonization using starch as carbon source and REC as the template. RECCs were modified with carbon disulfide (CS2) to obtain RECC xanthate (RECCX) composites. The hydrothermal process introduced a large number of oxygen-containing groups by depositing carbon layers onto the surface of REC, and the CS2 modification brought xanthate groups into REC. The adsorption process of Pb(2+) was investigated. Compared with REC, both RECC and RECCX could absorb more Pb(2+). The oxygen-containing groups increased the Pb(2+) adsorption in RECC. With the increasing of CS2 dosages, the adsorption capacities of RECCXs obviously improved due to the formation of the chelation between Pb(2+) and xanthate groups. The kinetic adsorption and the isotherm data matched the pseudo-second-order model and the Langmuir model well. The maximum adsorption capacities could reach 225.7 and 431.0 mg/g for RECC and RECCX, respectively. RECCXs were competitive with other absorbents, because REC, carbon layers and xanthate groups in RECCX composites all contributed to the Pb(2+) adsorption. RECCX could be easily regenerated with ethylenediaminetetraacetic acid disodium salt (EDTA) solution.