The influence of low irradiance and electrolytes on the mineralization efficiency of organic pollutants using the Vis-active photocatalytic tandem CuInS2/TiO2/SnO2

Many photocatalyitc laboratory experiments are developed at low (and different) irradiance values, making the results difficult to benchmark. This study analyzes the influence of the low irradiance, photon flux and the UV share on the photodegradation kinetics and efficiency of methylene blue (MB) using a hetero-structured thin film photocatalyst. The results show that the photon flux influences the process kinetic after an induction period and it was found that increasing irradiance has positive effect on the photo-catalytic efficiency, if UV does not exceed 25%, when photo -corrosion becomes significant. In the experimental conditions, the efficiency is also moderately influenced by the photon flux vales. Electrolytes are usually part of industrial or residential wastewaters, with multiple consequences among which accelerated photo -corrosion but also increased local charge transfer (thus decreased recombination) on the photocatalytic surface. The addition of two common electrolytes that are not hydrolysing (NaCl and CaCl2 into the dye solution was correlated with the chemical stability of the CIS/TiO2/SnO2 hetero-structure and the removal/mineralization efficiencies. The highest photodegradation efficiency (99%) was reached when 3.5% NaCl was used. The photocorossion increase up to 24.03% after 24 h when the photocatalyst is immersed in 3.5% NaCl electrolyte at 23 W/m(2) UV/vis irradiance and 120 mu mol/(m(2) s) photon flux. (C) 2017 Elsevier B.V. All rights reserved.