Treatment of Clinical Wastewater from Oil and Gas Industry Using Egg Shell-Titanium Oxide Composites as a Photocatalyst

Abstract Wastewater from the clinical services present in the oil and gas industries contains immeasurable amounts of antibiotics released into the environment. Untreated wastewater poses a serious risk to the ecosystem and public health when it is discharged into the environment. Consequently, these actions contribute to the concerning build-up of antibiotics in aquatic ecosystems, which in turn promotes antibiotic resistance. In this study, eggshell-titanium oxide composite was prepared as a photocatalyst to treat clinical wastewater from the oil and gas industry. The photocatalyst was prepared by processing eggshell and, then, homogenising it with titanium dioxide (TiO₂) using ethanol. The structural properties of the synthesised photocatalyst were characterised through FTIR and XRD analyses. The photocatalytic activities were examined by investigating the degradation of ciprofloxacin (CPX) using an LED photoreactor. To identify the effect of the parameters that affect the rate of degradation, batch experiments such as photocatalyst dose, reaction time, initial CPX concentration and pH were carried out. There is a significant impact of the system parameters on the rate of CPX degradation. With increasing photocatalyst dosage, the rate of ciprofloxacin elimination was shown to increase; at 0.1 g of eggshell, the maximum value of 94.42% was reached. Additionally, it was demonstrated that the clearance rate increased with time, and reached its maximum after 60 minutes, at 89.11% for 20 mg/L of eggshell-titanium oxide composite and 84.77% for 50 mg/L. Furthermore, the percentage CPX removal was discovered to increase as pH increased, and the removal of 90.53% maximum was achieved at the value 9 of pH. Langmuir-Hinshelwood models were studied in respect of the work, and the results obtained indicated that the photocatalysis kinetics data could fit well for the Langmuir-Hinshelwood model. It was also obtained from the results that the correlation coefficients (R²) for 20 mg/L eggshell-titanium oxide composite and 50 mg/L eggshell-titanium oxide composite were 0.9571 and 0.8417, respectively. In conclusion, the LED photoreactor with synthesised eggshell-titanium oxide composite has been discovered to offer a long-lasting and cost-effective environmental cleaning method. Therefore, eggshell-titanium oxide composites should be applied as a photocatalyst for treating wastewater from the clinical services in the oil and gas industries.