Monitoring kinetic and thermodynamic parameters of fluoride adsorption from aqueous solution by pks-based anion resins

Abstract

Fluoride is important for human health, but high level of fluoride concentrations can be threatening for both humans and animals as well as damaging to the environment. This paper delineates on fluoride adsorption onto palm kernel shell-based anion resins under various fluoride concentrations and temperatures. The equilibrium fluoride adsorption capacity demonstrated by the resins was observed 2.32 mg/g. Pseudo second-order model and Weber-Morris diffusion model were employed to evaluate the uptake rate and behavior of fluoride adsorption. The correlation coefficients (R 2) between experimental data and pseudo second-order model predictions was almost unity at all concentrations (5, 10 and 15 mg/L), indicating goodness of fit of the model. On the other hand, the thermodynamic study revealed the endothermic nature of the process indicated by the positive value of enthalpy change (2.671 kJ/mol). Moreover, the process is dominantly physical in nature along with a slight contribution of chemisorption.

Adsorption and Kinetics Modelling for Chromium (Cr6+) Uptake from Contaminated Water by Quaternized Date Palm Waste

“…Secondly, during the intermediate period, the rate of chromium removal decelerated. This slowdown is indicative of the saturation of active sites on the QDPW's surface, signaling the impending approach to equilibrium [15,18,22]. Finally, the equilibrium phase commenced approximately 60 min into the process.…”

“…If the value of "n" descends towards unity, the adsorption trajectory remains linear. A value less than one reflects a propensity towards chemisorption, while a value greater than 1 leans towards physisorption [7,15,27].…”

“…The utilization of bio-material-based adsorption is prevalent and holds significant potential to effectively eliminate chromium ions from contaminated water [9,[14][15][16]. The bio-materials can be quaternized which involves a particular surface chemical treatment that introduces groups (R-NR' 3+ ) onto lignocellulosic fibers.…”

“…Herein, R denotes structures such as cellulose, lignin or hemicellulose, while R' signifies an alkyl group. This modification can be achieved through epoxy substitution, enhancing the fiber's tendency for cationic or anionic materials via ion-exchange adsorption mechanisms [9,15,17,18]. Cellulose, a linear natural polymer, comprises β-D-glucopyranose monomers interconnected covalently through β-1,4-glycocidic bonds.…”