Synthesizes of graphene oxide grafted with chitosan and copper oxide nanoparticles for the removal of lambda-cyhalothrin and thiamethoxam insecticides from wastewater

Abstract

Abstract The residue of lambda-cyhalothrin (LCT) and thiamethoxam (TMX) insecticides are toxic systemic pyrethroid and neonicotinoid insecticides and their entrance into water bodies can have a toxic impact on aquatic and terrestrial life. Therefore, producing of economical, sustainable and effective adsorbents is immediately required for the removal of these insecticides from polluted water. In this study, the nanocomposite of graphene oxide (GO) grafted with chitosan (CS) and copper oxide nanoparticles (Cu-NPs) was synthesized, characterized and assessed, for the first time, for LCT and TMX removal from wastewater using sorption and mechanism studies. The removal of LCT and TMX was assessed by varying the adsorbent dose, initial concentrations of insecticides, pH, exposure time and temperature to achieve optimum sorption conditions. The nanocomposite provides more than 80% removal rate for 1400 mg/L of insecticides in an aqueous solution using only 100 mg of nanocomposite at 318 K in 120 min due to large surface area and pore volume. The adsorption equilibrium data best followed the Langmuir model, with an adsorption capacity of 153 and 193 mg/g for the LCT and TMX, respectively. The pseudo-second-order explained the kinetics best, and the thermodynamic study indicated that the process was spontaneous, and endothermic and proceeded with the increase in randomness. The suggested mechanisms of LCT and TMX sorption by GO-CS-Cu nanocomposite are hydrogen bonding and electrostatic attraction. The reusability study of GO-CS-Cu was executed up to five cycles and maintains its efficiency even after the considered cycles. In conclusion, the study proves the promising use of GO-CS-Cu as a stable, reusable and promising adsorbent for LCT and TMX removal from wastewater at the industrial level.