Novel low cost nanoparticles for enhanced removal of chlorpyrifos from wastewater: Sorption kinetics, and mechanistic studies

Abstract

Developing low cost sorbents for efficient elimination of organophosphorus pesticides from wastewater remains motivational. In this study, nanoparticles of water treatment residuals (nWTRs) derived from drinking water industry were produced and used for chlorpyrifos (CPF) removal from contaminated waste water. Batch sorption equilibrium study revealed that CPF sorption by nWTRs follow in order Langmuir > Temken > Kiselev adsorption models. The maximum adsorption capacity of nWTRs for CPF has shown 5 folds increase (50 mg g−1) compared to that of the conventional bulk WTRs and superior to most of the low cost adsorbents. Experimental parameters such as nWTR dosage, CPF concentration, and solution pH and exposure time were optimized. Remarkable CPF removal efficiency of 92% was achieved using nWTRs at pH 7 in contact time period of 30 min. The goodness-of-fit of the kinetic models tested showed that the power function model was successful in describing the kinetics of CPF adsorption with the lowest standard error (SE) of 0.0136. The thermodynamic parameters indicate the spontaneous and exothermic nature of CPF sorption on nWTRs sorbent. A possible mechanism of CPF removal by nWTRs includes formation of Al-CPF and Fe-CPF complexes and H-bonding. The novel nano-sorbent exhibits great potential as an efficient low cost sorbent for CPF removal from contaminated wastewater.

Keywords

• Nanomaterials
• Water remediation
• Cost effective
• Thermodynamics
• Sorption mechanism