Fast removal of methylene blue from aqueous solution by adsorption onto chitosan-g-poly (acrylic acid)/attapulgite composite

Batch adsorption experiments were carried out for the removal of methylene blue (MB) cationic dye from aqueous solution using chitosan-g-poly (acrylic acid)/attapulgite composites (CTS-g-PAA/APT) as adsorbent. The effects of attapulgite (APT) content, initial pH value of the dye solution and temperature on adsorption were investigated. Results showed that APT content of composites had some influence on adsorption capacities, and introducing a small amount of APT could improve adsorption capacity of chitosan-g-poly (acrylic acid) (CTS-g-PAA) to a certain extent. Results from kinetic experimental data showed that the adsorption rate of MB on CTS-g-PAA and CTS-g-PAA/APT with 30% of APT was fast, and more than 90% of the maximum adsorption capacities for MB were achieved within the initial 15 min. The adsorption behaviors of CTS-g-PAA and CTS-g-PAA/APT showed that the adsorption kinetics and isotherms were in good agreement with a pseudo-second-order equation and the Langmuir equation, and the maximum adsorption capacities reached 1873 and 1848 mg/g for CTS-g-PAA and CTS-g-PAA/APT, respectively. The discussion results of the desorption studies implied that CTS-g-PAA and CTS-g-PAA/APT can be used as promising adsorbents for the removal of MB from wastewater.