Green Synthesis of CoAl2O4@ZnO nanocomposite using Aamygdalus scoparia Spach gum and its photocatalytic activity for tetracycline degradation

A novel CoAl ₂ O ₄ @ZnO nanocomposite (NC) was synthesized via a green, low-cost, and simple sol-gel method using Amygdalus scoparia Spach gum. The photocatalytic efficacy of the produced CoAl ₂ O ₄ @ZnO NC was examined for the degradation of tetracycline (TC) under visible light. The CoAl ₂ O ₄ @ZnO NC analyzed using XRD, BET, UV-Vis-DRS, FESEM, TEM, EDX and Mapping. The XRD analysis confirmed the formation of CoAl ₂ O ₄ with a cubic spinel structure and ZnO with a hexagonal wurtzite structure. BET analysis revealed a specific surface area of approximately 40.045 m ² /g. The band gap energy was estimated to be around 3.0 eV using the Tauc equation. The CoAl ₂ O ₄ @ZnO NC demonstrated significant photocatalytic efficacy, obtaining 93% degradation of tetracycline in 45 min under visible light irradiation. LC-MS analysis identified multiple intermediate products during the comprehensive investigation of the photodegradation mechanism which confirmed the degradation pathway. The addition of ethanol as a scavenger led to reduced photocatalytic activity which demonstrates that hydroxyl radicals (•OH) play a crucial role in the degradation process. The nanocomposite maintained stability and photocatalytic efficiency throughout five repeated tests which showed minimal reduction in activity.