Diclofenac removal from water by photocatalysis- assisted filtration using activated carbon modified with N-doped TiO2

The aim of this study was to develop powdered and granular activated carbon modified with N doped TiO2, namely PAC-TiO2N and respective, GAC-TiO2N by sol-gel method, starting from commercial activated carbon, for the removal from water of diclofenac (DCF), an emerging pollutant. The synthesized materials were characterized systematically and morphostructural, light absorption and electrical charge properties were determined. The sorption and photocatalytic capacities of both materials were determined by batch experiments based on the kinetic models and the effect of operational parameters. GAC-TiO2N was selected for further testing in fixed bed-column experiments envisaging its potential integration with real drinking water treatment technology. The GAC-TiO2N tested in UV irradiation-assisted fixed bed-column filtration for DCF removal exhibited a great potential for practical application, by testing in simulated coexisting DCF and humic acids (HAs) and real surface water spiked with DCF (Bega River, Timisoara city, Romania). About 80% removal efficiency was noticed for both DCF and HAs and about 70% of the organic matter was removed (expressed as total organic carbon- TOC indicator). UV irradiation during filtration allowed the activation of the GAC-TiO2N filtration layer without TiO2 loss, which led to longer life-times due to the potential “self-cleaning” effect and its good stability.