Design and evaluation of a compact photocatalytic reactor for water treatment
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A compact reactor for photocatalytic oxidation and photocatalytic ozonation water treatment was developed and evaluated by using four model pollutants. Additionally, combinations of pollutants were evaluated. Specially produced Al2O3 porous reticulated monolith foams served as TiO2 carriers, offering a high surface area support. UV lamps were placed in the interior to achieve reduced dimensions of the reactor (12 cm in diameter × 20 cm in height). Despite its small size, the overall photocatalytic cleaning capacity was substantial. It was evaluated by measuring the degradation of LAS + PBIS and RB19 as representatives of surfactants and textile dyes, respectively. These contaminants are commonly found in household grey wastewater with phenol as a trace contaminant. Three different commercial photocatalysts and one mixture of photocatalysts (P25, P90, PC500 and P25 + PC500) were introduced in the sol-gel processing and immobilized on foamed Al2O3 monoliths. RB19 and phenol were easily degradable, while LAS and PBIS were more resistant. The experiments were conducted at neutral-acidic pH because alkaline pH negatively influences both photocatalyic ozonation (PCOZ) and photocatalysis. The synergistic effect of PCOZ was generally much more expressed in mineralization reactions. Total organic carbon TOC half lives were in the range of between 13 and 43 min in the case of individual pollutants in double-deionized water. However, for the mixed pollutants in tap water, the TOC half-life only increased to 53 min with the most efficient catalyst (P90). In comparison to photocatalysis, the PCOZ process is more suitable for treating wastewater with a high loading of organic pollutants due to its higher cleaning capacity. Therefore, PCOZ may prove more effective in industrial applications.
KeywordsPhotocatalysis Photocatalytic ozonation TiO2 Al2O3 monolith LAS PBIS Reactive Blue 19 Phenol
This work has been financially supported by Electrolux S.P.A. and the Slovenian Research Agency (research core funding no. P2-0377 and P1-0134, Belgian-Slovenian project “Development of advanced TiO2-based photocatalyst for the degradation of organic pollutants from wastewater”). The doctoral study of M. Kete was partly cofinanced by the European Union through the European Social Fund. Cofinancing was carried out within the framework of the Operational Program for Human Resources Development for 2007–2013, 1. Development priority: Promoting entrepreneurship and adaptability; priority 1.3: Scholarship Scheme. The doctoral study of O. Pliekhova has been funded by INFINITY project in the framework of the EU Erasmus Mundus Action 2.
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