The removal of diazinon from aqueous solution by chitosan/carbon nanotube adsorbent

The removal of diazinon using low-cost sorbent Chitosan/Carbon Nanotube (CHN-CNT) from aqueous solutions has been investigated in the present study. A protected cross linking method was used to synthesis of CHN-CNT with 2.5% of MWCNT. MWCNT is a promising candidate for improving chitosan mechanical properties. Scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) and Thermogravimetric analyzer (TGA) were used to characterize the prepared adsorbent. Tests were done to evaluate the effects of solution pH, the amount of CHN-CNT, diazinon concentration, contact time and solution temperature on adsorption of diazinon onto CHN-CNT. Results showed that CHN-CNT at a low amount of 0.5 g/L, in contact time 60 min and pH 5.5, could remove 82.5% of the diazinon at initial concentration 5 mg/L. The Langmuir, Freundlich and Sips isotherm models were used to analyze the equilibrium experimental data. Equilibrium adsorption isotherm data exhibited better fit to the Sips isotherm model, where the heterogeneity factor (n = 0.66) indicated heterogeneous adsorption characteristics, with a maximum adsorption capacity of 222.86 mg/g. Also the experimental adsorption data was fitted well to the pseudo-second-order model. Overall, the use of CHN-CNT due to the easier to prepare, high performance in adsorption, simple and effective regeneration make CHN-CNT as a promising adsorbent to eliminate the pesticide from contaminated streams.