Horizontally rotating disc recirculated photoreactor with TiO₂-P25 nanoparticles immobilized onto a HDPE plate for photocatalytic removal of p-nitrophenol

ABSTRACT

In this study, a horizontally rotating disc recirculated (HRDR) photoreactor equipped with two UV lamps (6 W) was designed and fabricated for photocatalytic removal of p-nitrophenol (PNP). Photocatalyst (TiO₂) nanoparticles were immobilized onto a high-density polyethylene (HDPE) disc, and PNP containing solution was allowed to flow (flow rate of 310 mL min^–1) in radial direction along the surface of the rotating disc illuminated with UV light. The efficiency of direct photolysis and photocatalysis and the effect of rotating speed on the removal of PNP were studied in the HRDR photoreactor. It was found that TiO₂-P25 nanoparticles are needed for the effective removal of PNP and there was an optimum rotating speed (450 rpm) for the efficient performance of the HRDR photoreactor. Then effects of operational variables on the removal efficiency were optimized using response surface methodology. The results showed that the predicted values of removal efficiency are consistent with experimental results with an R₂ of 0.9656. Optimization results showed that maximum removal percent (82.6%) was achieved in the HRDR photoreactor at the optimum operational conditions. Finally, the reusability of the HRDR photoreactor was evaluated and the results showed high reusability and stability without any significant decrease in the photocatalytic removal efficiency.

KEYWORDS:

• Rotating disc photoreactor
• immobilized TiO₂-P25
• photocatalytic removal
• p-nitrophenol
• response surface methodology

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Mohammad A. Behnajady http://orcid.org/0000-0002-9929-8921

Hojjat Dadkhah http://orcid.org/0000-0001-5288-5283

Hamed Eskandarloo http://orcid.org/0000-0001-7241-119X

Additional information

Funding

The authors thank the Islamic Azad University, Tabriz Branch for financial and other means of support.