Adsorption of organophosphate pesticides from aqueous solution: a review of recent advances

Organophosphate pesticides (OPPs) are a type of pesticide that is commonly used to eliminate pests that cause agricultural produce shortages. One of the methods that is effective in its mitigation from the aqueous environment is adsorption. This paper is aimed at reviewing the removal of OPPs from aqueous media via adsorption. The goal was to carefully study the trends of research findings by various authors over the past eleven years, analyzing key results, observing patterns and similarities, and identifying interesting areas that future researchers should consider. It was observed that the highest reported adsorption capacity for OPPs is 4460 mg/g for chlorpyrifos using mesoporous MgFe 2 O 4 adsorbent. Adsorption mechanisms were dominated by hydrogen bonding, complexation reactions, electrostatic interactions, and electron donor–acceptor interactions. The Langmuir or Freundlich classical isotherm models were the best-fit in most cases to describe OPPs’ adsorption equilibrium, while the pseudo-second-order model was the best-fit for the modeling of OPPs’ uptake kinetics. Thermodynamic studies revealed that OPPs’ uptake is usually spontaneous (with a few exceptions). Competitive adsorption studies showed that the uptake capacity of OPPs by the various adsorbents decreased in the presence of negatively charged ions and anions. Most OPPs exhibited a removal efficiency > 70% even after five regeneration cycles. The utilization and toxicity of OPPs as well as the implications of OPPs’ adsorption on sustainable water resource management were also discussed in this review. Interesting areas for future research were identified in the economics of the adsorption processes. Graphical abstract