Abstract
Brilliant Green is adsorbed on TG and ATG through multi-linearity process, which indicate that two or more steps were involved during the process. TG prefers intra-particles diffusion mechanism, meanwhile ATG favours external surface adsorption mechanism.
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The potentiality of tannin gel (TG) and amine modified tannin gel (ATG) has been found as highly effective, eco-friendly and cheap adsorbents for removal of Brilliant Green (BG) dye. In each case, the most efficient adsorption occured at pH 7 with 88.38% for TG and 94.05% removal for ATG, respectively. The adsorption kinetics for TG was found to follow pseudo-first-order kinetic model along with intraparticle diffusion, and for ATG it was found to follow pseudo-second order kinetic model. The experimental data were found to best fit with langmuir isotherm (r2>0.99 for both gels) with maximum monolayer adsorption capacity of 8.55mg/g for TG and 20.41mg/g for ATG. The negative values of Gibb’s free energy (ΔG°) of both gels indicate the spontaneous nature of the adsorption process.The positive values of ΔH° with respect to both gels suggest the endothermic adsorption nature along with positive values of entropy changes (ΔS°).