Optimization of cationic dye adsorption on activated spent tea: Equilibrium, kinetics, thermodynamic and artificial neural network modeling

Abstract

Activated spent tea (AST) was prepared and characterized by using different techniques such as BET, FTIR and SEM. It is used for methylene blue (MB) dye removal from aqueous solution in a batch system. Experimental results showed that natural basic pH, increased initial dye concentration, and high temperature favored the adsorption. Analysis based on the artificial neural network (ANN) indicated that the adsorbent dose and time with the relative importance of 30.03 and 35.44%, respectively, appeared to be the most influential parameters in the MB adsorption. The adsorption of MB was relatively fast and the Avrami fractional order and pseudo-second-order kinetic models showed satisfactory fit with the experimental data. The equilibrium data were well fitted by the Langmuir and Liu isotherm models, with a maximum sorption capacity of 104.2 mg/g. Also, the obtained values of thermodynamic parameters showed that the adsorption of MB onto AST is endothermic and spontaneous. The results of this study indicated that AST was a reliable adsorbent for removing cationic dyes from wastewater.

Simultaneous adsorption of lead and aniline onto magnetically recoverable carbon: optimization, modeling and mechanism

“…The thermodynamic parameters provide a deeper mechanistic understanding of the adsorption process at different temperatures. The thermodynamic parameters of the adsorption process comprise of standard enthalpy (Δ H o ), standard entropy (Δ S o ) and free energy change (Δ G o ) . Vant Hoff equation shown in Equation (8) reveals the relationship between the temperature ( T ) and equilibrium constant of the adsorption ( K = q e / C e ).…”

“…The thermodynamic parameters of the adsorption process comprise of standard enthalpy (ΔH o ), standard entropy (ΔS o ) and free energy change (ΔG o ). 29 Vant Hoff equation shown in Equation (8) reveals the relationship between the temperature (T) and equilibrium constant of the adsorption (K = q e /C e ). Here, q e is the amount of Pb(II) or An adsorbed at equilibrium (mg g −1 ) and C e is the equilibrium concentration of Pb(II) or An in solution (mg L −1 ).…”

Preparation and characterization of MWCNT–COOH–cellulose–MgO NP nanocomposite as adsorbent for removal of methylene blue from aqueous solutions: isotherm, thermodynamic and kinetic studies

“…It means that the adsorption of methylene blue dye onto nanocomposite surfaces is an exothermic process. Entropy (∆S°), the adsorption free energy (∆G°), and standard enthalpy (∆H o ) for methylene blue dye adsorption onto MWCNT-COOH-cellulose (A1), MWCNT-COOH-cellulose with MgO directly (A2), and MWCNT-COOH-cellulose with MgO indirectly (A3) surfaces were calculated to evaluate the MB dye removal thermodynamic feasibility using the adsorbents in this study [22][23][24][25][26]:…”

Application of Fe3O4@C catalyzing heterogeneous UV-Fenton system for tetracycline removal with a focus on optimization by a response surface method

“…From the results, it was found that the correlation coefficient (R 2 ) of the Langmuir model was higher than that of the Freundlich model, indicating that Langmuir model fitted very well the experimental data. The TC adsorption onto Fe3O4@C would thus follow a homogeneous (monolayer) mechanism [32].…”