Preparation of cationic wheat straw and its application on anionic dye removal

Cationic wheat straw has been prepared for anionic dyes removal from aqueous solution. It included two steps: pretreatment of straw to remove most lignin and the quaternization of the residual straw. Acetic acid pulping was used to remove lignin and the quaternization was carried out in an aqueous suspension. The dye removal results revealed that the maximum adsorption capacity of the cationic straw for dye AB92 could arrive 1072 g/kg. The effect of temperature, reaction time and the extents of the quaternization on the adsorption capacity were studied. The pseudo-second-order kinetic model was applied to describe the kinetic data and the rate constants were evaluated. The Freundlich and Langmuir adsorption models were used to describe the mechanism. The adsorption data indicated that the capacity of the adsorbents was depended obviously on the initial pH of dye solution and initial dye concentration.