Facile microwave synthesis of pine cone derived C-doped TiO 2 for the photodegradation of tetracycline hydrochloride under visible-LED light.

Pine cone derived carbon was doped into TiO2 via a facile microwave procedure at different powers, different from other conventional synthesis methods. The materials were adequately characterized and applied in the photodegradation of 5 mg/L tetracycline hydrochloride (TA) under visible-LED light. The XRD results showed that all materials exist as both anatase and rutile phase. However, both the microwave power and the carbon content of the composite material inhibited the conversion of anatase into rutile. The composite material synthesized at a microwave power of 800 W (CT800), displayed the highest band gap energy (3.14 eV) but showed the least electron-hole recombination rate. Hence, CT800 exhibited the highest apparent rate constant of 9.9 × 10-3 min-1 and a half-life of 70 min. An inverse relationship between OH• radical scavenger (isopropanol) and the percentage degradation by CT800 suggests that OH• is majorly responsible for the degradation of TA. Recyclability studies revealed that after 4 cycles of photocatalytic degradation reactions, CT800 retained approximately 83% performance confirming its stability and reusability.