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- Title
Paraben degradation using catalytic ozonation over volcanic rocks.
- Authors
Gomes, João F.; Quinta-Ferreira, Maria Emília; Costa, Raquel; Quinta-Ferreira, Rosa M.; Martins, Rui C.
- Abstract
Parabens are widely used as antimicrobial and preservatives in pharmaceutical and personal care products and are continuously reaching the water streams. Conventional wastewater treatments are proven inefficient on the removal of this kind of contaminants from wastewater. Therefore, catalytic ozonation appears as a suitable option, due to the oxidant power of ozone and its high capacity of hydroxyl radical generation in the presence of a suitable catalyst. The main drawback of catalytic ozonation is related with the choice of stable and active catalysts at low cost. On this way, two volcanic rocks were tested to enhance the removal of a mixture of parabens by ozonation, improving their degradation. Indeed, catalytic ozonation with volcanic rock allowed total paraben degradation using a transferred ozone dose (TOD) of 55 mg/L which corresponds to a reduction of about threefold the amount of TOD comparatively with single ozonation (170 mg/L of TOD). Due to the presence of semiconductors on volcanic rock composition, the effect of UVA irradiation on paraben degradation was analyzed. The neutral and basic conditions enhanced catalytic ozonation comparatively to acid conditions. Higher pH values allowed a total methylparaben degradation with 35 mg O3/L, whereas for low pH values, 55 mg O3/L was required. The use of a radical scavenger proven that hydroxyl radicals are the main responsible for paraben degradation with catalytic ozonation. This was confirmed through the analysis of the by-products, where 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid (3,4-diHBA), 2,4-dihydroxybenzoic acid, and hydroquinone were quantified.
- Subjects
CATALYTIC activity; OZONIZATION; PARABENS; VOLCANIC ash, tuff, etc.; RADICALS (Chemistry); COST effectiveness
- Publication
Environmental Science & Pollution Research, 2018, Vol 25, Issue 8, p7346
- ISSN
0944-1344
- Publication type
Article
- DOI
10.1007/s11356-017-1025-8