Adsorption of methyl orange onto protonated cross-linked chitosan

The adsorption of methyl orange (MO) from aqueous solutions on protonated cross-linked chitosan was studied in a batch system. The results showed that the adsorption of MO onto protonated cross-linked chitosan was affected significantly by initial MO concentration, adsorbent dosage, adsorption temperature, and contact time. The pH value of solution had a minor impact on the adsorption of MO in a pH range of 1.0-9.1. The equilibrium isotherms at different temperatures (293, 303, and 313 K) and pH values (4.5, 6.7, and 9.1) were investigated. Langmuir model was able to describe these Equilibrium data fitted perfectly. The maximum monolayer adsorption capacities obtained from the Langmuir model were 89.29, 130.9, and 180.2 mg/g at 293, 303, and 313 K, respectively. Adsorption kinetics at different concentrations (100, 200 and 300 mg/L) and pH values (4.5, 6.7 and 9.1) were also studied. The kinetics was correlated well with the pseudo second-order model.