Background and objective: Insecticides are one of the most important pollutants in water. Diazinon is one of the phosphorus pesticides that can be found in aquatic ecosystems in Iran. The toxic effect of diazinon is inhibition of the enzyme acetyl cholinesterase (Ache). In this study, MWCNT/ Fe₃O₄ efficiency was investigated.

Materials and Methods: In this study, co-precipitation method was used for the Fe₃O₄ synthesis on multiwall carbon nanotube. The pH, contact time, adsorbent dose, pollutant concentrations and temperature parameters were investigated. Diazinon was measured by Gas chromatography method.

Results: The results showed that the optimum conditions for diazinon removal were pH 6, contact time of 15 minutes, and  adsorption dose of 0.6 g/l. So, the absorption efficiency increases with increasing of temperature and decresing of pollutant concentration. The diazinon adsorption corresponded with Freundlich isotherm (R2> 0.99) more than Langmuir isotherm model (R2> 0.90).

Conclusion: The results show that the magnetic carbon nanotubes with Fe₃O₄ can be suitable adsorbent for diazinon removal from aquatic environment.