Functionalization of nanocellulose as adsorbents for malathion

The use of pesticides such as malathion has increased due to agricultural development and the diversification of plant pests, which has caused severe impacts on human health and the ecosystem. The research objectives are to synthesize and characterize functionalized cellulose nanofibers (CNF) with glycidyltrimethyl ammonium chloride (GTMAC) and 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC) using techniques Fourier Transform Infrared Spectroscopy (FTIR), CHNS Elemental analyzer, Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (FESEM-EDX), Transmission Electron Microscopy (TEM) and Zeta Potential. Whilst, the adsorption capacity parameters of CNF, CNF-GTMAC and CNF-CHPTAC towards malathion, including malathion concentration, adsorbent weight and contact time, were optimized using Response Surface Methodology (RSM). The adsorbents weight (1.0 – 5.0 mg), contact time (30 – 150 s) and initial concentration of malathion (6.0 – 14.0 mg/L) were studied to determine the optimum condition using RSM. The adsorption capacity of CNF towards malathion was found to be 25.25 mg/g with an adsorbent weight of 1.0 mg, 126 s of contact time and an initial concentration of malathion 9.0 mg/L. Likewise, the adsorption capacity of CNF-GTMAC was obtained at 54.34 mg/g with an adsorbent weight of 1.0 mg, contact time of 130 s and initial concentration of malathion 10.0 mg/L. As for CNF-CHPTAC, it was obtained at 78.74 mg/g with an adsorbent weight of 1.0 mg, contact time of 128 s and initial concentration of malathion 9.0 mg/L. The results reveal that CNF-CHPTAC exhibits the highest adsorption capacity, followed by CNF-GTMAC, with CNF demonstrating the lowest adsorption capacity. These results suggest that the cationic functionalization of CNF leads to significantly higher adsorption capacities of malathion compared to unmodified CNF. The adsorption isotherms and kinetics model were examined under optimal conditions. The experimental data concerning the adsorption isotherms of malathion onto CNF, CNFGTMAC and CNF-CHPTAC demonstrated a better fit with the Langmuir isotherm model compared to the Freundlich model. Whilst, the experimental data concerning the adsorption kinetics of malathion onto CNF indicated the pseudo-second-order model suggesting that chemical adsorption process takes place. Whereas, CNF-GTMAC and CNF-CHPTAC followed the pseudo-first-order model, signifying that the adsorption process is an electrostatic interaction.