Removal of tetracycline from aqueous solution by ultrasound and ultraviolet enhanced persulfate oxidation

Tetracycline (TC) is the second most-consumed antibiotic and is produced worldwide. Environmental contamination with TC is considered as a serious concern in public health. Thus, many attempts have been made to discover new removal processes of TC. This study was conducted to evaluate the efficiency removal of TC from aqueous solution during combined ultrasonic (US), ultraviolet (UV) radiation, and persulfate (PS) process. The effect of various parameters including contact time (0-120 min), TC concentration (10-70 mg/L), pH (3-10), PS concentration (2-6 mM), and the input US power (100-500 W) were investigated in this process. At the end of each process, the remaining TC was measured by spectrophotometer (261 nm). The results implied that each of the UV and US processes alone did not have considerable removal efficiency of TC, as these values for UV and US processes were 41.69% and 12.36%, respectively. Additionally, the highest removal efficiency rate of TC was approximately 96.29% which was observed in combined UV/US/PS process during optimum conditions, including pH = 10, TC concentration = 10 mg/L, PS concentration = 4 mM, and input US power = 500 W. Our study supports the notion that UV/US/PS process can be applied to remove antibiotics such as TC or others with the same structure as well to optimize their biodegradation.