Photocatalytic degradation of oily waste and phenol from a local South Africa oil refinery wastewater using response methodology

E K Tetteh; S Rathilal; D B Naidoo

doi:10.1038/s41598-020-65480-5

Photocatalytic degradation of oily waste and phenol from a local South Africa oil refinery wastewater using response methodology

Sci Rep. 2020 Jun 1;10(1):8850. doi: 10.1038/s41598-020-65480-5.

Authors

E K Tetteh¹, S Rathilal², D B Naidoo²

Affiliations

¹ Faculty of Engineering and the Built Environment, Department of Chemical Engineering, Durban University of Technology, Steve Biko Campus Block S4 Level 1, Box 1334, Durban, 4000, South Africa. ektetteh34@gmail.com.
² Faculty of Engineering and the Built Environment, Department of Chemical Engineering, Durban University of Technology, Steve Biko Campus Block S4 Level 1, Box 1334, Durban, 4000, South Africa.

Abstract

The photocatalytic degradation of a local South Africa oil refinery wastewater was conducted under UV radiation using an aqueous catalyst of titanium dioxide (TiO2), Degussa P25 (80% anatase, 20% rutile) in suspension. The experiment was carried out in a batch aerated photocatalytic reactor based on a central composite design (CCD) and analyzed using response surface methodology (RSM). The effects of three operational variables viz. TiO₂ dosage (2-8 g/L), runtime (30-90 minutes), and airflow rate (0.768-1.48 L/min) were examined for the removal of phenol and soap oil and grease (SOG). The data derived from the CCD, and the successive analysis of variance (ANOVA) showed the TiO₂ dosage to be the most influential factor, while the other factors were also significant (P < 0.0001). Also, the ANOVA test revealed the second-order of TiO₂ dosage and runtime as the main interaction factors on the removal efficiency. To maximize the pollutant removal, the optimum conditions were found at runtime of 90 minutes, TiO₂ dosage of 8 g/L, and an aeration flow rate of 1.225 L/min. Under the conditions stated, the percentage removal of phenol (300 ± 7) and SOG (4000 ± 23) were 76% and 88% respectively. At 95% confidence level, the predicted models developed results were in reasonable agreement with that of the experimental data, which confirms the adaptability of the models. The first-order kinetic constants were estimated as 0.136 min^-1 and 0.083 min^-1 for SOG and phenol respectively.

Publication types

Research Support, Non-U.S. Gov't