Efficient removal of crystal violet and eosin B from aqueous solution using Syzygium cumini leaves: A comparative study of acidic and basic dyes on a single adsorbent

摘要

The adsorption capabilities of Syzygium cumini leaves were investigated for crystal violet and eosin B using batch adsorption method. Removal conditions were optimized by varying operational parameters like pH, dose of adsorbent, contact time and temperature. Presence of salts had a profound effect on the adsorption and the experimental data for both adsorbates, providing good correlation with the Temkin, Langmuir and Freundlich patterns, but differing from Dubinin-Radushkevich model. Maximum adsorption capacity was found to be 38.75 mg/g for crystal violet and 16.28mg/g for eosin B respectively. Boyd-Adamson-Myers, Morris-Weber and Bangham's surface mass transport models revealed that film diffusion was the rate controlling process and followed pseudo-second order kinetics. Activation energy was estimated to be 57.265 and 6.721 kJ/mol for crystal violet and eosin B respectively. Adsorption of crystal violet is endothermic and that of Eosin B is exothermic but both were spontaneous at all temperatures. To study the bulk removal of the dyes, column operations were made. The exhausted columns were regenerated by eluting HCl solution and almost 91.94% of CV and 58.08% of EB were recovered from columns, respectively.