The preparation, characterization, and environmental application of chitosan-coated quartz sand for Congo red adsorption have been investigated. The absorbent was characterized by Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscope (SEM). The experiments were carried out in a batch system to optimize operation variables: contact time, Congo red concentration, absorbent dosage, temperature, and pH. The optimum conditions for Congo red adsorption were pH 5, 45 degrees C and contact time of 4 h. An amount of 1 g of chitosan-coated quartz sand could successfully remove 96% of the dye form 50 mg/L Congo red solution. The adsorption kinetics and equilibrium isotherms showed that the sorption processes were better fitted by pseudo-second order equation and Langmuir equation, respectively. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012