Removal of Cr(VI) from aqueous solution by surfactant-modified kaolinite

Removal of Cr(VI) from aqueous solution by hexadecyltrimethylammonium chloride (HDTMA) modified kaolinite (HMK) was investigated, where the maximum adsorptive capacity reached 27.8 mg/g Cr(VI) using HMK compared with only 0.7 mg/g using unmodified natural kaolinite (NK). The adsorption of Cr(VI) on HMK can be well described by the Langmuir isotherm, and the kinetic adsorption of Cr(VI) on both HMK and NK fitted a pseudo-second-order model. FTIR analysis showed that surface modified HDTMA was responsible for the high adsorptive capacity of Cr(VI). HMK was used to remove Cr(VI) from an electroplating wastewater.