Reactive dye removal from wastewater using a chitosan nanodispersion Original Research Article

Adsorption of an azo reactive dye, C.I. Reactive Red 120 (RR120), from aqueous solution on chitosan and on a chitosan nanodispersion has been studied. The nanodispersion was prepared using a mixture of chitosan and sodium tripolyphosphate. The results showed that the adsorption of RR120 on dissolved chitosan and on the chitosan nanodispersion was affected significantly by initial dye concentration, sorbent amount, temperature, pH and ionic strength of the solution. Maximum dye removal for both adsorbents was at a pH of 4–5 and the adsorption of the reactive dye on both dissolved chitosan and the nanodispersion gave good fit to the Langmuir isotherm model. The adsorption capacity of the nanodispersion was around 910 mg g− 1, much higher than of dissolved chitosan, which was 51 mg g− 1. The adsorption of the dye on the chitosan nanodispersion reached equilibrium much faster than on dissolved chitosan. The kinetics of the adsorption correlated well with the pseudo-second order model.