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Article

The Effect of Thermal Treatment on the Physicochemical Properties of Minerals Applied to Heterogeneous Catalytic Ozonation

1
Laboratory of Chemical and Environmental Technology, Department of Chemistry, Aristotle University, 54124 Thessaloniki, Greece
2
Laboratory of Analytical Chemistry, Department of Chemical Engineering, Aristotle University, 54214 Thessaloniki, Greece
*
Author to whom correspondence should be addressed.
Sustainability 2020, 12(24), 10503; https://doi.org/10.3390/su122410503
Received: 30 October 2020 / Revised: 8 December 2020 / Accepted: 14 December 2020 / Published: 15 December 2020
(This article belongs to the Special Issue Municipal Wastewater Management)
In order to enhance the efficiency of heterogeneous catalytic ozonation, the effect of thermal treatment on three commonly used and inexpensive minerals, i.e., zeolite, talc and kaolin (clay), which present different physicochemical properties as potential catalysts, has been examined for the removal of para-chlorobenzoic acid (p-CBA). p-CBA is considered a typical micro-pollutant, usually serving as an indicator (model compound) to evaluate the production of hydroxyl radicals in ozonation systems. The catalytic activity of selected solid catalysts was studied for different pH values (6, 7 and 8) and different temperatures (15 °C, 25 °C and 35 °C). The mechanism of radicals’ production was also verified by the addition of tert-butyl alcohol (TBA). The respective thermal behavior study showed that the point of zero charge (PZC) of these minerals increased with the increase of applied treatment temperature, as it removed crystalline water and hydroxyls, thus improving their hydrophobicity. Circa-neutral surface charge and the presence of hydrophobicity were found to favor the affinity of ozone with solid/catalytic surfaces and the subsequent production of hydroxyl radicals. Therefore, zeolite and talc, presenting PZC 7.2 and 6.5 respectively, showed higher catalytic activity after thermal treatment, while kaolin with PZC equal to 3.1 showed zero to moderate catalytic efficiency. The degradation level of p-CBA by oxidation was favored at 25 °C, while the pH value exerted positive effects when it was increased up to 8. View Full-Text
Keywords: heterogeneous catalytic ozonation; PZC; p-CBA; minerals; thermal treatment; micropollutants removal heterogeneous catalytic ozonation; PZC; p-CBA; minerals; thermal treatment; micropollutants removal
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MDPI and ACS Style

Psaltou, S.; Kaprara, E.; Kalaitzidou, K.; Mitrakas, M.; Zouboulis, A. The Effect of Thermal Treatment on the Physicochemical Properties of Minerals Applied to Heterogeneous Catalytic Ozonation. Sustainability 2020, 12, 10503. https://doi.org/10.3390/su122410503

AMA Style

Psaltou S, Kaprara E, Kalaitzidou K, Mitrakas M, Zouboulis A. The Effect of Thermal Treatment on the Physicochemical Properties of Minerals Applied to Heterogeneous Catalytic Ozonation. Sustainability. 2020; 12(24):10503. https://doi.org/10.3390/su122410503

Chicago/Turabian Style

Psaltou, Savvina, Efthimia Kaprara, Kyriaki Kalaitzidou, Manassis Mitrakas, and Anastasios Zouboulis. 2020. "The Effect of Thermal Treatment on the Physicochemical Properties of Minerals Applied to Heterogeneous Catalytic Ozonation" Sustainability 12, no. 24: 10503. https://doi.org/10.3390/su122410503

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