Abstract
After the dyeing process, part of the dyes used to color textile materials are not fixed into the substrate and are discharged into wastewater as residual dyes. In this study, a heterogeneous photocatalytic process combined with microfiltration has been investigated for the removal of C.I. Disperse Red 73 from synthetic textile effluents. The titanium dioxide (TiO2) Aeroxide P25 was selected as photocatalyst. The photocatalytic treatment achieved between 60% and 90% of dye degradation and up to 98% chemical oxygen demand (COD) removal. The influence of different parameters on photocatalytic degradation was studied: pH, initial photocatalyst loading, and dye concentration. The best conditions for dye degradation were pH 4, an initial dye concentration of 50 mg·L−1, and a TiO2 loading of 2 g·L−1. The photocatalytic membrane treatment provided a high quality permeate, which can be reused.
Highlights
Synthetic dyes are widely used in the textile industry
A proper removal of disperse dye in the effluent would allow the water to be reused, which is an important advantage from the economic and environmental points of view. Taking into account these considerations, this paper investigates the potential use of a photocatalytic membrane reactor for the degradation of C.I
No significant dye degradation was observed after 180 min of UV irradiation
Summary
Synthetic dyes are widely used in the textile industry. About 15% of the dyes consumed are lost in the textile effluents [2]. The presence of a very low concentration of dyes in wastewater is highly visible [7]. The dyes are classified according to how they are applied in the dyeing process. The most common dyes are reactive, acid, and disperse. Reactive dyes are water-soluble, mainly applied to cotton. Acid dyes are water-soluble and applied from an acidic solution to nylon, wool, silk, and some modified acrylic textiles. Disperse dyes are used for polyesters fibers. They have very low water solubility, so they are applied as a dispersion in the dyeing process [8]
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