Droplet flow-assisted heterogeneous electro-Fenton reactor for degradation of beta-blockers: response surface optimization, and mechanism elucidation

  • Hakimu Nsubuga
  • Chanbasha BasheerEmail author
  • Almaz Jalilov
  • Muhammad Baseer Haider
  • Abdulaziz A. Al-Saadi
Research Article


In this study, we report an effective degradation method for trace level beta-blockers (propranolol and acebutolol) in hospital wastewater using a new droplet flow-assisted heterogeneous electro-Fenton reactor (DFEF) system. Biogenic iron–carbon nanocomposites (RHS/C-x% Fe) as eco-friendly and low-cost heterogeneous Fenton catalysts were synthesized from rice husk via hydrolytic sol–gel routes. Here, we demonstrate the use of natural air as a nebulizing agent for fast and continuous catholyte air saturation and Fenton catalyst transfer to the cathode electrode. The effects of key operational parameters were evaluated and optimized using central composite design. Results clearly indicated that enhanced beta-blocker degradation was mainly dependent on the interactive effects of electrolysis time, current density, and catalyst dosage. Fast degradation efficiencies (≥ 99.9%) was recorded at neutral pH conditions. The decay followed pseudo-first-order kinetics with degradation rates of up to 2.72 × 10−2 and 2.54 × 10−2 min−1 for acebutolol and propranolol, respectively. The synergistic contribution of OHbulk attributable to DFEF process and OHadsorbed for anodic oxidation (AO) at the anode electrode significantly enhanced the degradation process. Compared to AO, the conventional flow-assisted electro-Fenton (FEF), and the batch electro-Fenton (BEF), DFEF degradation efficiency followed a decreasing order: DFEF ˃ FEF ˃ BEF˃ AO. This trend in performance was mainly due to the fast and continuous cathodic electro-generation of H2O2 and Fe2+ regeneration. Additionally, in order to elucidate degradation mechanism, we used a combination of DFEF approach with liquid chromatography-tandem mass spectrometry analysis. This approach demonstrates a simple, cleaner, and highly efficient degradation approach for trace level recalcitrant pollutants in a complex aquatic matrix, without the need for external chemical addition and pH adjustment.


Electro-Fenton Hydrolytic sol–gel routes Heterogeneous catalyst Beta-blockers Central composite design 



The authors gratefully acknowledge the funding support of the Deanship of Scientific Research at King Fahd University of Petroleum and Minerals through a Project Grant No. 151024. Hakimu is also grateful to KFUPM for sponsoring his Ph.D. studies.

Supplementary material

11356_2019_4551_MOESM1_ESM.docx (608 kb)
ESM 1 (DOCX 607 kb)


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© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of ChemistryKing Fahd University of Petroleum and MineralsDhahranSaudi Arabia
  2. 2.Department of PhysicsKFUPMDhahranSaudi Arabia

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