Abstract
Chitosan/zeolite-A composite (CS/ZA) was synthesized and characterized as a multifunctional, eco-friendly, and enhanced adsorbent for three species of organophosphorus pesticides (acephate (AC), omthosate (OM), and methyl parathion (MP)). The CS/ZA composite achieved maximum capacities of 650.7 mg/g, 506.5 mg/g, and 560.8 mg/g for AC, OM, and MP, respectively. The kinetic and equilibrium inspection validate Pseudo-first order and Langmuir properties for the uptake of the pesticide by CS/ZA. Moreover, the thermodynamic parameters declared the nature of these reactions as spontaneous, favorable, and exothermic processes. The values of Gaussian energy, enthalpy, and free energy suggested a complex uptake mechanism involving chemical and physical reactions for the assessed pesticides. The CS/ZA composite showed promising affinities for the AC, OM, and MP pesticides even in the existence of other inorganic anions or metal ions. The adsorption properties of CS/ZA as a fixed bed (6 cm) in column systems achieved removal percentages of 78% (AC), 57.6% (OM), and 74.3% (MP) considering the selected flow rate (5 mL/min), concentration (25 mg/L), and pH (pH 8). The CS/ZA displayed considerable stability and recyclability during the removal of the three pesticides.
•Chitosan/zeolite-A was used in the adsorption of organophosphorous pesticides.•The qmax of acephate, omthosate, and methyl parathion are 650, 506, and 560 mg/g.•The uptake behavior of both ions follow Langmuir and Pseudo-First order models.•The uptake of the ions occurred by physical exothermic and spontaneous reactions.•The column tests showed promising removal of the pesticides by the composite bed.