Assessment of molecularly imprinted polymers (MIPs) in the preconcentration of disperse red 73 dye prior to photoelectrocatalytic treatment.

Magnetic molecularly imprinted polymers (MMIPs) have become a research hotspot due to their two important characteristics: target recognition and magnetic separation. This paper presents the preparation, characterization, and optimization of an MMIP for the preconcentration of disperse red 73 dye (DR73) and its subsequent efficient degradation by photoelectrocatalytic treatment. The MMIPs were characterized by scanning electron microscopy (SEM), which revealed homogeneous distribution of the particles. Excellent encapsulation of magnetite was confirmed by transmission electron microscopy (TEM). A study of dye binding showed that the dye was retained more selectively in the MIP, compared to the NIP. The release of DR73 from the imprinted polymers into methanol and acetic acid was analyzed by UV-Vis spectrophotometry. The extracts showed higher absorbance values for MMIP, compared to MNIP, confirming greater adsorption of dye in the MMIP material. The extracts were then subjected to photoelectrocatalytic treatment. LC-MS/MS analysis following this treatment showed that the dye was almost completely degraded. Hence, the combination of MMIP extraction and photoelectrocatalysis offers an alternative way of selectively removing an organic contaminant, prior to proceeding with its complete degradation.

Efficiency comparison of ozonation, photolysis, photocatalysis and photoelectrocatalysis methods in real textile wastewater decolorization.

Treatment of real effluents from industries using AOPs stands to be an imperative task of crucial importance yet quite huge a challenge largely given the nature of complexity of these wastewaters. The present work sought to develop a versatile system aimed at the treatment of real wastewater using a bubbling annular reactor, which enables us to test the efficiency of photolysis; photocatalysis, photoelectrocatalysis and direct ozonation using oxygen or ozone as gas flow. A TiO2 nanotubes electrode was used as photocatalyst in photocatalytic and photoelectrocatalytic measurements with and without coupling with ozonation under pH 3.0 and pH 8.0 leading to 50% of color removal after 60 min reaction. However, the results indicated 90% of color removal upon the bubbling of ozone after 15 min of treatment. A synergistic effect was observed in all experiments using the AOPs in the presence of ozone under both pH values. Interestingly though, 85% of decolorization was obtained through direct ozonation without any change in the effluent following 10 min of treatment. The results were discussed in terms of electric energy per order and were compared to those reported previously. For real textile wastewater, ozonation appears to be a promising candidate for full-scale effluent decolorization.