The widespread use of malathion enhances agricultural
plant productivity
by eliminating pests, weeds, and diseases, but it may lead to serious
environmental pollution and potential health risks for humans and
animals. To mitigate these issues, environmentally friendly hydrogel
adsorbents for malathion were synthesized using biodegradable polymers,
specifically cellulose, β-cyclodextrin (β-CD), poly(vinyl
alcohol) (PVA), and biobased epichlorohydrin as a cross-linker. This
study investigated the effects of the cellulose-to-PVA ratio and epichlorohydrin
(ECH) content on the properties and malathion adsorption capabilities
of β-CD/cellulose/PVA hydrogels. It was found that the gel content
of the hydrogels increased with a higher cellulose-to PVA and ECH
ratio, whereas the swelling ratio decreased, indicating a denser structure
that impedes water permeation. In addition, various parameters affecting
the malathion adsorption capacity of the hydrogel, namely, contact
time, pH, hydrogel dosage, initial concentration of malathion, and
temperature, were studied. The hydrogel prepared with a β-CD/cellulose/PVA
ratio of 20:40:40 and 9 mL of ECH exhibited the highest malathion
adsorption rate and capacity, which indicated an equilibrium adsorption
capacity of 656.41 mg g–1 at an initial malathion
concentration of 1000 mg L–1. Fourier transform
infrared spectroscopy (FTIR), ζ-potential, and X-ray photoelectron
spectroscopy (XPS) and NMR spectroscopy confirmed malathion adsorption
within the hydrogel. The adsorption process followed intraparticle
diffusion kinetics and corresponded to Freundlich isotherms, indicating
multilayer adsorption on heterogeneous substrates within the adsorbent,
facilitated by diffusion.