Quaternary Ammonium Impregnated Chitosan for the Decontamination of Wastewater from Carcinogenic Dyes

Chitosan, a well-known biopolymer, has been impregnated with tetrabutylammonium bromide using the reflux method. The synthesized adsorbent, tetrabutylammonium impregnated chitosan(C-TBA) was subjected to intense characterization using various spectral techniques which confirms impregnation. The pH point of zero charge was found to be 8.2 which indicate the suitability of the material for both anionic and cationic dyes. C-TBA was employed as adsorbent for the removal of two potent carcinogenic dyes, namely, Congo red (CR) and Crystal violet (CV). Batch experiments were carried out to study the effects of pH of dye solution, contact time, adsorbent dose, adsorbate concentration and temperature. A number of adsorption isotherm models namely, Langmuir, Freundlich, R-P, D-R, Temkin, and Harkin-Jura were studied. The best fit isotherm model was judged by plotting the non-linear plots. Maximum monolayer adsorption capacity of C-TBA towards adsorption of CR was found to be 12.66 mg g(-1) and for CV 0.86 mg g(-1). Adsorption kinetics was well fitted to pseudo-second-order model and thermodynamics show that the process of adsorption was spontaneous. Statistical analysis as well as column adsorption studies was also carried out.

Automated summary

This study impregnated chitosan with tetrabutylammonium bromide to obtain tetrabutylammonium impregnated chitosan(C-TBA) as an adsorbent. Various spectral techniques were used to characterize C-TBA, confirming impregnation. The pH point of zero charge was 8.2, indicating its suitability for both anionic and cationic dyes. Batch experiments showed that C-TBA had a maximum monolayer adsorption capacity of 12.66 mg g(-1) for Congo red (CR) and 0.86 mg g(-1) for Crystal violet (CV). The adsorption kinetics followed a pseudo-second-order model and the thermodynamics indicated the process was spontaneous.