2012•Advanced materials researchOpen access
Coating Humic Acid on Vermiculite Surface for the Adsorption of Nickel(II)
Xu Deng, Shi Yong Wei
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Abstract
Surface properties and Ni(II) adsorption characteristics of HA-vermiculite were investigated and compared with those of vermiculite. The cation exchange capacity (CEC), pH at zero point of charge (pHZPC), and surface charge at pH 6.5 and surface fractal dimension of HA-vermiculite were 44.69 cmol/kg, pH 2.57, -0.418 mmol/g, and 2.45, respectively. Compared to vermiculite, the CEC, surface negative charge and surface fractal dimension of HA-vermiculite increased, and the pHZPC of HA-vermiculite decreased. The adsorption data for Ni(II) by HA-vermiculite could be fitted by Langmuir isotherm (R2 =0.982) and also by Freundlich isotherm (R2 =0.987). At pH 6.5, the Langmuir maximum adsorption capacities for Ni(II) of vermiculite and HA-vermiculite were 11.86 and 19.41 mg/g, respectively.