Enhanced removal of crystal violet by low cost alginate/acid activated bentonite composite beads: Optimization and modelling using non-linear regression technique

Abstract

Adsorption feasibility of crystal violet dye (CV+) onto acid-activated bentonite clay, entrapped in a polymeric matrix of calcium alginate bead examined in this work. Operational parameters have been investigated, isotherms were analyzed using non-linear regression model and data obtained optimized by Box-Behnken model. Pseudo-nth order fits well with the kinetic data obtained, and the reaction order n was found to be between 0.925 and 3.269. Desorption tests showed that the recovery of CV+ decreased from 92.39 to 84.59% in the tenth cycle. The maximum adsorptions of crystal violet onto alginate/acid activated bentonite beads (A-AAB), alginate/bentonite beads (AB), and acid activated bentonite clay (AAB) were 582.4, 498.2 and 229 mg dye g(-1) respectively. The thermodynamic parameters indicate that the adsorption process of CV+ is endothermic and more effective at high temperatures. (C) 2014 Elsevier Ltd. All rights reserved.