Kinetic, Isotherm and Thermodynamic Studies of the Adsorption of Thymol Blue onto Powdered Activated Carbons from <i>Garcinia cola Nut</i> Shells Impregnated with H<sub>3</sub>PO<sub>4</sub> and KOH: Non-Linear Regression Analysis

Abstract

In this work, activated carbons (ACs) prepared by chemical activation of garcinia cola nut shell impregnated with H 3 PO 4 (CBH 2/1) and KOH (CBK 1/1) were used to study the kinetics, equilibrium and thermodynamics of the adsorption of thymol blue from aqueous solution. The characterization of ACs showed the BET measurements gave surface area and total pore volume respectively of 328.407 m 2 •g −1 and 0.1032 cm 3 •g −1 for CBH 2/1 and 25.962 m 2 •g −1 and 0.03 cm 3 •g −1 for CBK 1/1 ; elemental analysis showed a high percentage of carbon in both ACs. Influence of parameters such as initial pH, contact time, adsorbent mass, initial concentration, ionic strength and the effect of temperature on the removal of thymol blue from aqueous solution were studied in batch mode. The studies showed that equilibrium adsorption was attained after 60 minutes for the two ACs, adsorption capacity increased with increasing concentration of thymol blue, and maximum adsorption capacity was obtained at an acidic environment with pH 2. Avrami's non-linear kinetic expression was the best suited for describing the adsorption kinetics of thymol blue onto ACs, while equilibrium data showed that the three-parameter isotherms better described the adsorption process since R 2 > 0.96, and the error functions were lowest for all of them.

Optimized Removal of Hydroquinone and Resorcinol by Activated Carbon Based on Shea Residue (Vitellaria paradoxa): Thermodynamics, Adsorption Mechanism, Nonlinear Kinetics, and Isotherms

“…Positive entropy values ΔS 0 also indicate increased randomness, including the number of species at the solid-liquid interface during sorption. Similar results were obtained during adsorption of hydroquinone in solution by granular activated carbon [1] and adsorption of hydroquinone by hydroxyethyl cellulose functionalized with magnetic/ionic liquid [49].…”

“…We notice in Table 9 that the values of the coefficient of determination R 2 for all the isotherm models are close to unity (R 2 > 0.99) and the values of the corresponding error functions are low, which suggest that these models are suitable for effectively describing experimental data at equilibrium. e Sips model, having the high values of R 2 and the low values of χ 2 , shows a distribution of the molecules of HQ and of R on a heterogeneous surface of CAK-S, thus presenting energetically different adsorption sites [49].…”

Kinetic and Isotherm Studies of the Adsorption Phenacetin onto Two Copper Porous Coordination Compounds: Nonlinear Regression Analysis

“…e value of 1/n less than 1 in the Freundlich model shows that there is an affinity between the surface of the materials and the adsorbate solution. ese values support the hypothesis that the surfaces of the different materials are heterogeneous [33].…”

“…e validation of the Freundlich model allows us to say that it is a multilayer adsorption on a heterogeneous surface for the two adsorbents, and the interactions between the adsorbent's surface and the adsorbate play a significant role in the adsorption process [33]. e value of 1/n less than 1 in the Freundlich model shows that there is an affinity between the surface of the materials and the adsorbate solution.…”

Application of Fourier Transform Infrared Spectrophotometry Method for Analysis of Metformin Hydrochloride in Marketed Tablet Dosage Form

“…The coefficient of determination obtained was 0.9985 with a regression equation of Y = 4.3221 × X + 56.4045. The determination coefficient obtained was appropriate with values more than 0.99, which indicated that the peak area (Y or ordinate) can be used for determination of concentration (X or abcis) (Kuete et al, 2020).…”