Combined ozonation process and adsorption onto bentonite natural adsorbent for the o-cresol elimination

ABSTRACT

This work studies the removal of o-cresol from wastewater by using ozonation followed by adsorption onto sodium natural bentonite (Na-Bent). The degradation of o-cresol was followed by UV-Vis. During ozonation, 2-methylbenzoquinone (2-mBQ) and 2-methylhydroquinone (2-mHQ) were identified as two of the main by-products, while the pH decrease suggested the breakage of aromatic compounds into smaller organic acids. After 30 min treatment, the o-cresol degradation for 250–62.5 mg/L solutions was found between 64–85%, respectively. Next, the wastewater containing persistent o-cresol and by-products was contacted with Na-Bent adsorbent. The solutions and physicochemical properties of Na-Bent were analysed, before and after adsorption, by UV-Vis, FTIR, XRD and N₂ adsorption-desorption. Moreover, equilibrium and kinetic experiments were carried out to study the adsorptive properties of the Na-Bent. While sole ozonation or adsorption failed on the remediation of o-cresol solutions, the obtained results show that the contact of ozonated solutions with Na-Bent led to almost total removal of the o-cresol initial concentrations (between 96% and 99%). This excellent performance is assigned to the high volume of interlayer micropores and the suitable surface chemistry of this natural adsorbent.

KEYWORDS:

• Elimination
• O-cresol
• ozonation
• adsorption
• sodium naturalbentonite
• industrial wastewater

Acknowledgments

The authors would like to thank the Algerian Directorate General of Scientific Research and Technological Development (DGRSDT) and the Ministry for Higher Education and Scientific Research for the financial support for this work. In addition, the Spanish Ministerio de Economía y Competitividad and FEDER funds (RYC-2017-23618) are gratefully appreciated.

Disclosure statement

No potential conflict of interest was reported by the author(s).