Modification of kaolin natural zeolite by graphitic carbon nitride (g -C۳N۴) and its application as photocatalyst in photodegradation of Diazinon

In this study, a nanocomposite based on graphitic carbon nitride (g -C₃N₄) and kaolinite was synthesized and evaluated for its photocatalytic performance in the photodegradation of pollutants. Kaolinite was initially used as a support material due to its favorable characteristics, including high surface area, thermal stability, natural abundance, low cost, and environmental compatibility. These features contribute to improved dispersion of the active phase, enhanced surface contact, and more efficient charge transfer during photocatalytic processes. To optimize the adsorption performance, kaolinite underwent both acid-washing and base-washing treatments, and its ability to adsorb diazinon was examined independently. The results showed that acid-washed kaolinite exhibited superior adsorption capacity compared to the base-washed form. Therefore, the acid-washed kaolinite was selected as the support for g -C₃N₄ in the final nanocomposite. Graphitic carbon nitride was synthesized from urea as the precursor through a thermal treatment process at ۵۵۰ °C and then combined with acid-washed kaolinite in a ۱:۳ weight ratio to produce the target nanocomposite. To investigate the effects of key operational parameters on the degradation process, experimental design was carried out using the Box-Behnken Design (BBD) method. Three variables diazinon concentration, nanocomposite dosage, and irradiation time were considered as independent factors. The optimal conditions were determined to be ۵۰ ppm of diazinon, ۱ g of nanocomposite, and ۲ h of light exposure, under which a degradation efficiency of ۹۳.۹۱% was achieved. Additionally, the influence of pH was studied using the One-Variable-at-a-Time method, and the results indicated that pH=۷ led to the highest degradation efficiency. Overall, the combination of acid-washed kaolinite with g -C₃N₄ significantly enhanced the photocatalytic performance compared to pure g -C₃N₄. This improvement is attributed to better pollutant adsorption, increased surface interaction, and more effective utilization of visible light. Therefore, the synthesized nanocomposite can serve as an efficient and environmentally friendly photocatalyst for the removal of organic pollutants from aqueous environments.

کلیدواژه ها:

Natural kaolin zeolite ، photodegradation ، Diazinon ، g_C ۳N۴@Kaolin composite