Hydrodynamic cavitation and photocatalysis for effluent treatment: Key operating parameters and synergistic effects

Sebastien J. De-Nasri, Varaha P. Sarvothaman, Caroline Kelly, Sanjay Nagarajan, Panagiotis Manesiotis, Peter K.J. Robertson, Vivek V. Ranade

Research output: Contribution to journalArticlepeer-review

3 Citations (SciVal)

Abstract

A combination of hydrodynamic cavitation and photocatalysis (HC-PC) is a promising water treatment technology for the removal of recalcitrant pollutants. In this work, we investigated influence of key parameters of this hybrid technology such as initial concentration, catalyst loading, pH, re-circulating flow rate and cavitation device/scale on degradation of three model pollutants (coumarin, paracetamol and dichloroaniline). Unlike previous HC-PC studies, the individual and combined systems were investigated for each parameter to determine their effect on system performance and overall synergy. We report a dependence of logKow for both systems, with highest removal (100% in 20 min with AC-PC, 37% in 120 min, or 350 passes, with HC-PC) and synergy (Synergistic index of 2.8 and 1.2 for AC-PC and HC-PC, respectively) associated with the more hydrophobic compound, dichloroaniline. HC-PC performance increased and synergy decreased with increasing catalyst loading, and the inverse effect was found with initial concentration (C0: 17.5 to 70 ppm). Similarly, pH decreased performance but increased synergy and low re-circulating flow rate increased performance but decreased synergy. Detailed analysis of these results indicated the utilisation of in-situ generated H2O2 from recombined OH radicals is the main contributor of the observed synergy, and not physical interactions between cavities and photocatalyst particles. Following this, for the first time, influence of cavitation device type (based on linear flows and swirling flows) and device scale on overall performance of HC-PC system was quantified. Vortex based cavitation device was found to provide a 20% and 25% higher performance and synergy compared to a linear flow based cavitation device like orifice. The results presented here provide valuable insights into the synergy of HC and photocatalytic systems.

Original languageEnglish
Article number145241
Number of pages14
JournalChemical Engineering Journal
Volume473
Early online date5 Aug 2023
DOIs
Publication statusPublished - 1 Oct 2023

Data Availability Statement

Data will be made available on request.

Keywords

  • Advanced oxidation process
  • Hybrid techniques
  • Hydrodynamic cavitation
  • Photocatalysis

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering

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