Excellent driven rapid photocatalytic activity with high reusable magnetic nanocomposite in tetracycline degradation under simulated sunlight

Abstract

The present experimental study aimed to determine the efficiency of CuS-coated magnetic acti- vated carbon nanocomposite for the photocatalytic removal of tetracycline (TC) under simulated sunlight. The effects of pH 3, 5, 7, 9, contaminant concentration 5–10–20–50–100 mg/L, nanocat- alyst dose 0.025, 0.25, 0.5, 1, 1.5, 2, and 2.5 g/L, and exposure time 1–200 min on the TC removal by the synthesized nanocatalyst were investigated. The maximum removal efficiency was achieved at pH = 9. The TC removal efficiency increased with increasing exposure time and decreasing TC concentration from 100% to 52.1%. The TC removal ratio initially (increased with increasing the nanocatalyst dose from 0.025 to 1.5 g/L (from 37.52% to 89.13%) but started to decrease (54.43%) once the dose was raised above a certain level. The kinetics of the process was found to closely fol- low the pseudo-first-order kinetic model with R 2 > 0.9. After determining the optimal conditions for TC removal with the synthesized nanocatalyst under simulated sunlight, the chemical oxygen demand (COD) and total organic carbon (TOC) removal rates under the same conditions were also experimentally investigated. This investigation showed the COD and TOC removal rates to be 78.13% and 65.81%, respectively. The test results also showed the high recoverability and reusability of the synthesized nanocomposite, with only a 6.08% drop in removal efficiency after six cycles. Also, the effects of some scavenging agents were studied and the results showed the most important role of IPA as a hydroxyl radical scavenger in decreasing the photocatalytic activity of nanocomposite. This confirms that hydroxyl radicals play the most important role in the degradation of tetracycline molecules with respect to e – /h + pairs or • O 2– . Overall, the results demonstrated the excellent tetracycline removal capability of the synthesized nanocomposite under simulated sunlight.