Get access

Sunlight-Assisted Fenton Reaction Catalyzed by Gold Supported on Diamond Nanoparticles as Pretreatment for Biological Degradation of Aqueous Phenol Solutions

Authors

  • Dr. Sergio Navalon,

    1. Departamento de Química, Universidad Politécnica de Valencia, C/Camino de Vera, s/n, 46022 Valencia (Spain)
    Search for more papers by this author
  • Roberto Martin,

    1. Departamento de Química, Universidad Politécnica de Valencia, C/Camino de Vera, s/n, 46022 Valencia (Spain)
    Search for more papers by this author
  • Dr. Mercedes Alvaro,

    1. Departamento de Química, Universidad Politécnica de Valencia, C/Camino de Vera, s/n, 46022 Valencia (Spain)
    Search for more papers by this author
  • Prof. Hermenegildo Garcia

    Corresponding author
    1. Instituto de Tecnología Química CSIC-UPV, Av. de los Naranjos s/n, 46022 Valencia (Spain), Fax: (+34) 963-877-809
    • Instituto de Tecnología Química CSIC-UPV, Av. de los Naranjos s/n, 46022 Valencia (Spain), Fax: (+34) 963-877-809
    Search for more papers by this author

Abstract

Gold nanoparticles supported on Fenton-treated diamond nanoparticles (Au/DNPs) have been reported as one of the most efficient solid catalysts effecting the Fenton reaction, achieving a turnover number (TON) as high as 321 000. However, at room temperature the main limitation for the catalytic activity of Au/DNPs is the pH of the solution, which should be less than 5. In this paper, we report that exposure of Au/DNPs to sunlight enhances the catalytic activity of Au/DNPs up to the point that it can promote the Fenton reaction at room temperature even at slightly basic pH values. Also, in addition to performing a deep Fenton treatment and considering that the excess of H2O2 used in the process should be minimized, we have achieved in our study, using a mild Fenton reaction promoted by Au/DNPs under sunlight irradiation, an optimum in the biodegradability, a minimum in the ecotoxicity, and no toxicity for the Vibrio fischeri test. The results have shown that, by using an H2O2-to-phenol molar ratio of 5.5 or higher, it is possible to achieve a high biodegradability as well as a complete lack of ecotoxicity and of Vibrio fischeri toxicity. The stability of Au/DNPs was confirmed by analyzing the gold leached to the solution and by performing four consecutive reuses of the catalyst with initial pH values ranging from 4 to 8. It was observed that, after finishing the reaction and exhaustive washings with basic aqueous solutions, the initial reaction rate of the used catalyst is recovered to the value exhibited by the fresh solid. Overall, our study shows that the synergism between catalysis and photocatalysis can overcome the limitations found for dark catalytic reactions and that the reaction parameters can be optimized to effect mild Fenton reactions aimed at increasing biodegradability in biorecalcitrant waste waters.

Get access to the full text of this article

Ancillary