Adsorption of chloroanilines from aqueous solutions on the modified halloysite

Batch removal of 3-, 4-chloroaniline and 3,4-dichloroaniline from an aqueous solution using unmodified and acid-activated halloysite was investigated in this study. The influence of acid concentration used for digesting the halloysite, contact time as well as the concentration of chloroaniline solutions was reported. The results show that the adsorption of 4-chloroaniline was greatly enhanced by using a sulfuric acid-treated halloysite, as compared to the unmodified halloysite. A comparison of kinetic models applied to the adsorption of chloroanilines on an acid-treated halloysite was evaluated for pseudo first-order, pseudo second-order, and intraparticle diffusion kinetic models. The chemisorption pseudo-second order kinetic model was found to correlate the experimental data well. The adsorption mechanism of acid-treated halloysite -chloroaniline system complied well with the Langmuir model in the case of 4-chloroaniline and 3,4-dichloroaniline and with the Freundlich model for 3-chloroaniline. (C) 2014 Elsevier B.V. All rights reserved.