Insight into the Adsorption Properties of β-Cyclodextrin/Zeolite-A Structure for Effective Removal of Cd2+, PO43-, and Methyl Parathion; Kinetics and Advanced Equilibrium Studies

Synthetic p-cyclodextrin/zeolite-A (CD/ZA) composite was evaluated as a potential adsorbent for Cd2+, PO43-, and methyl parathion (MP). The CD/ZA particles exhibit higher Cd2+ (223 mg/g), PO43- (196.2 mg/g), and MP (368.7 mg/g) Q(sat) values than zeolite-A reflecting the impact of the integrated polymer. The Cd2+, PO43-, and MP uptake follows the classic assumptions of Pseudo-First order kinetics and Langmuir isotherm. The monolayer equilibrium model of one energy site was applied for more details about the adsorption systems. Based on the model findings, the CD/ZA particles can adsorb up to 4 Cd2+ ions (n = 2.76 to 3.03), 3 PO43- ions (n = 2.2 to 2.31), and 2 MP molecules (n =1.89 to 1.94) per site. The adsorption site densities of Cd2+ (75.9 mg/g), PO43- (87.9 mg/g), and MP (194.7 mg/g) illustrate the high uptake properties of MP. Based on the classic kinetics, equilibrium, and Gaussian energies (< 8 kJ/mol) findings, the pollutants were adsorbed by physical processes in monolayer and homogenous forms. This was supported by the adsorption energies (< 40 kJ/mol) that reflected the effect of van der Waals, hydrogen bonding, and dipole bonding forces. The thermodynamic functions validate the spontaneous and exothermic behaviors of the adsorption systems. The composite display significant recyclability and affinity for the studied contaminants under the competitive effect of other ions (Pb2+, Zn2+, NO3-, SO42-, malachite green, and chlorpyrifos).

Automated summary

This study evaluated the potential of synthetic polymer β-cyclodextrin/zeolite-A (CD/ZA) composite as an adsorbent for Cd2+, PO43-, and methyl parathion (MP). The CD/ZA particles exhibited higher adsorption capacities for the contaminants compared to zeolite-A and showed significant recyclability. The adsorption processes were found to be physical in nature, occurring in monolayer and homogeneous forms.