Preparation of P-doped CdS nanorods as an efficient photocatalyst for the degradation of the emerging pollutant tetracycline antibiotic under blue LED light irradiation

Abstract

Excessive drug usage and sewage discharges containing antibiotics have caused water contamination due to the rapid growth of pharmaceutical industries. Tetracycline (TC) is one of the most frequently applied antibiotics having a significant impact on the aquatic environment, water quality and human health and thus effective approaches for TC removal from water are urgently needed. Here, we have fabricated P-doped CdS (CdS-P_0.8) nanorods (NRs) by one-step thermal phosphorization treatment for TC degradation through photocatalytic reaction in the presence of blue and white LED light irradiation. Synthesized photocatalysts were characterized to authenticate the incorporation of P atoms on the CdS NR surface using XPS, XRD, ICP-OES and EDX mapping analyses. CdS-P_0.8 NRs have greater photocatalytic activity for tetracycline degradation under blue LED light irradiation. TC degradation on CdS-P_0.8 NRs followed pseudo-first order kinetics for both LED light sources. In the presence of blue LED light at an intensity of 10 mW cm⁻², TC degradation efficiency and pseudo-first order rate constants of CdS-P_0.8 NRs for the photocatalytic degradation reaction reached 95.4% and 0.13396 min⁻¹ in 20 minutes without any supplemental oxygen sources. Scavenging experiments demonstrate that reactive oxygen species are produced during the photocatalytic degradation of tetracycline. As a result, due to the extensive utilization of photogenerated oxidative species such as h⁺, O₂˙⁻ and OH˙, CdS-P_0.8 NRs demonstrated high photocatalytic tetracycline degradation efficiency in 20 minutes. Our findings shed more light on nonmetal P doping on CdS materials and other semiconductors, exploring new possibilities for photocatalytic degradation to efficiently reduce the amount and toxicity of TC antibiotics in wastewater.