Orange II adsorption on palygorskites modified with alkyl trimethylammonium and dialkyl dimethylammonium bromide — An isothermal and kinetic study

We modified an Australian palygorskite with octadecyl trimethylammonium bromide (ODTMA) and dioctadecyl dimethylammonium bromide (DODMA) at different concentrations, and assessed these organo-palygorskites for adsorption of the anionic dye orange II. The surface and pore structure of the modified palygorskites were analysed by nitrogen adsorption. Orange II adsorption on palygorskites modified with DODMA and ODTMA quantity equivalent to twice the cation exchange capacity (CEC) of palygorskite was as high as 92 and 88 mg/g at 25 °C. The ODTMA and DODMA modified palygorskites did not differ greatly in their adsorption capacities. We also studied the influence of various experimental parameters such as the amount of adsorbent, mixing time, temperatures and pH values on the adsorption of orange II by the organo-palygorskites. Both electrostatic attraction as well as van der Waals interaction controlled the adsorption over the whole range of concentrations. This study demonstrates the potential application of organo-palygorskites for the remediation of anionic dyes from wastewater.