Kinetics and Thermodynamics of Acid Red 1 Adsorption on Used Black Tea Leaves from Aqueous Solution

Abstract

This study presents the investigation of kinetics and thermodynamics of adsorption of Acid Red 1 (AR1) from aqueous solution on used black tea leaves (UBTL) as a biosorbent. The effects of initial dye concentration, solution pH and temperature on the adsorption kinetics were evaluated through batch adsorption experiments. Different kinetic model equations such as pseudo first order, pseudo second order, Elovic and Intra-particle diffusion were applied to the experimental data to evaluate their validity and determined their respective parameters. The results revealed that the adsorption kinetics is well described by pseudo second order kinetic equation. The equilibrium amounts adsorbed, calculated from the pseudo second order kinetic plots for different initial concentrations, were used to construct the adsorption isotherm which is well expressed by Langmuir equation compared with Freundlich one and the maximum adsorption capacity was 30.03 mg/g. Again, the equilibrium amounts adsorbed, calculated from the pseudo second order kinetic plots for different temperatures, were increased with the increase of adsorption temperature indicating the adsorption is endothermic. The calculated values of apparent activation energy (Ea = 3.35 kJ/mol), enthalpy change (∆H = +30.05 kJ/mol), entropy change (∆S = +0.119 kJ/mol) and free energy change (∆G) revealed that the adsorption of AR1 on UBTL at pH 2.0 was endothermic, spontaneous and physical in nature. The equilibrium amount adsorbed for different initial pH of solution, calculated from pseudo order kinetic plots, was found to be decreased with increase of solution pH from 2.0 to 8.0 suggesting the adsorption mechanism is dominated by electrostatic interaction between positive surface of UBTL at pH 2.0 and negative AR1 dye molecules.

Eco-Friendly Detoxification of Congo Red Dye from Water by Citric Acid Activated Bioadsorbents Consisting of Watermelon and Water Chestnuts Peels Collected from Indigenous Resources

“…The higher the ∆ H 0 value for citric acid treated biosorbents in comparison to their raw peels reflecting the tighter adsorbate-adsorbent interactions at their surface interfaces, resulting in the efficient eradication of CGR from the water system. The contortion and deformation at the adsorbate-adsorbent interface associated with entropy change ( ∆ S 0 ) is also calculated from Equation (25) [79, 80]. High calculated ∆ S 0 for adsorptive removal of CGR by CPWM and CPWC is 443 and 225 Jmol -1 K -1 , respectively, as compared to 168 Jmol -1 K -1 for PWM and 138 Jmol -1 K -1 for PWC, respectively, listed in Table 5.The increased energies of activation ( ∆ E a ) calculated from Arrhenius Equation (20), for the removal of CGR from the aqueous environment on acid-treated CPWM and CPWC, are 145 and 76 kJmol -1 , respectively, whereas on PWM and PWC are 57 and 48 kJmol -1 , respectively, indicating the fast and efficient adsorptive removal of CGR on citric acid-treated adsorbents [81].…”

Removal of Crystal Violet and Acid Red 1 Dyes from Wastewater by Mechanically Activated Talc

“…The experiments were conducted in 50 mL round bottom flasks where 0.05 g of talc sample was agitated with 25 mL of dye solutions (20-400 mg/L) at different pH (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), temperatures (20 -60 C), and at various contact time (0-240 min.) using a mechanical shakertype WISD at 250 rpm.…”

“…Extreme cases can result in malignancy, severe eye irritation that can cause blindness for life as well as and kidney failure in addition to being carcinogenic [8,9]. AR1 (C18H13N3Na2O8S2) is a common anionic azo dye that dissolves in water, groups of sulfonic acid exist in the dye structure, in an aqueous solution, giving it a negative charge [10]. AR1 is fundamentally used in wool dying through a strong acid medium and can be simply applied to fabrics of wool and fiber of polyamide.…”