Adsorptive removal of crystal violet from aqueous solution by cross-linked chitosan coated bentonite

Abstract

Crystal violet has been reported as a recalcitrant dye molecule that persists in environment for long period and poses toxic effects in environment. The objective of this work is the study of adsorption of crystal violet dye solution using cross-linked Chitosan Coated Bentonite (CCB) Beads. The adsorptive removal of crystal violet from aqueous solution CCB beads was investigated. CCB beads were prepared by cross-linking reaction between chitosan and bentonite under acidic condition. CCB beads were characterized by Fourier Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis. Batch adsorption studies were carried out by observing the effect of experimental parameters such as pH, amount of adsorbent, contact time, concentration of adsorbate, temperature, etc. The optimized working conditions were found to be the solution pH of 5.0, adsorbent dose 50 mg, contact time 30 min and dye concentration 100 mg L−1. Fixed bed column studies were also conducted with inlet dye concentrations of 10 and 20 mg L−1, feed flow rate 5 mL min−1 and bed height 4 cm. The column type continuous flow operations were used to obtain the breakthrough curves. The breakthrough capacity, exhaustion capacity and degree of column utilization were evaluated from the plots. The material was found to have high adsorption capacity towards crystal violet in column mode.