In this article, surface modification of feldspar using hexadecyltrimethyl ammonium bromide (HDTMA) and its dye removal ability in single and binary systems was studied. Acid Black 1 (AB1) and Acid Red 14 (AR14) were used as model dyes. The monocomponent Langmuir isotherm model was applied to experimental data and the isotherm constants were calculated for both dyes. The monolayer coverage capacities of surfactant-modified feldspar (HDTMA-feldspar) for AB1 and AR14 dyes in single solution system were found as 6.369 mg/g and 3.984 mg/g, respectively. It was observed that the equilibrium uptake amounts of AB1 and AR14 dye in binary mixture onto sorbent decreased with increasing concentrations of the other dye resulting in their antagonistic effect. Equilibrium adsorption for binary systems was analyzed by using the Extended Langmuir and Jain and Snoeyink Modified Extended Langmuir models. The rate of kinetic processes of single and binary dye systems onto adsorbent was described by using two kinetics adsorption models. The pseudo-second-order model was the best choice among the kinetic models to describe the adsorption behavior of single and binary dyes onto HDTMA-feldspar. Thermodynamic parameters showed that dye adsorption on HDTMA-feldspar were exothermic and unspontaneous in nature. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012