The facile adsorptive removal of commercial grade chlorpyrifos from water using nano-magnetite

The removal of Chlorpyrifos (CPF) from its contaminated water is vital even at a trace level due to its severe toxicity. The treatment of CPF in a bulk water medium is usually cost- and energy-intensive due to certain unavoidable mass-transfer limitations. Therefore, the preconcentration of CPF in a bulk water medium may aid in addressing the aforementioned issues. The adsorption-based techniques can aid in the preconcentration of CPF before its treatment. In this work, the pure phase of nano-magnetite (Fe₃O₄) (Fd_3m; a = 0.5936 nm) (particle size = 24 nm) as the low-cost adsorbent was developed for the effective adsorptive removal of CPF from water. The BET surface area of nano-magnetite was estimated to be 60.16 m² g⁻¹. The developed nano-magnetite showed an excellent CPF removal efficiency of > 96% at the neutral pH within 2 h of contact time at 303 K. It was observed that the CPF removal performance followed second-order kinetics. The adsorption capacity at equilibrium conditions was not altered significantly at a broader temperature range (293–313 K). At optimum conditions, the adsorption capacity of nano-magnetite was calculated to be 190.08 mg g⁻¹. The CPF removal performance and the characteristics of nano-magnetite were not affected significantly for the tested ten cycles. Although the equilibrium time for the CPF removal performance increased when it was spiked in tap water, however, the removal performance (~ 80%) was considerably higher. Therefore, nano-magnetite can be used as an adsorbent for the preconcentration of CPF for its effective treatment in CPF-contaminated bulk water media.