Open-cell ceramic foams covered with TiO2 for the photocatalytic treatment of agro-industrial wastewaters containing imazalil at semi-pilot scale

Abstract

Background

Imazalil is a fungicide widely used in postharvest agroindustry, which causes a negative impact on the environment. To remove it from agro-industrial wastewaters, solar heterogeneous photocatalysis, with the photocatalyst fixed onto support, constitutes a promising technique. In this work, two open-cell ceramic foams (with and without carbon) were evaluated as TiO2 supports. Technical and economic feasibility of photocatalysis with TiO2 supported on ceramic foams were assessed. Methods

Foams were covered with TiO2 by dip-coating and subsequent calcination. The obtained systems were characterized by different techniques. Lab-scale removal of imazalil in pure and real water matrices was studied for both materials. The highest performance system was also evaluated at semi-pilot scale. Significant findings

The C-free support led to the highest photoactivity in both water matrices at lab-scale. No TiO2single bondC synergistic effect was observed due to photon absorption phenomena detected for the support with graphite. The C-free foams coated with TiO2 can be used in solar reactors to decontaminate wastewater with imazalil, achieving 95% degradation and a nontoxic condition for Allivibrio fischeri bacteria at accumulated energy values less than 10 kJ·L−1. This technique can be adapted to each real situation through the adequate selection of the number of photocatalytic converters exposed to sunlight. After economic evaluation, the experimental technology could be considered cost-effective.