**6. Conclusion**

The association of the electrochemical properties with the photocatalytic properties of a semiconductor, have allowed for the development of a promising system, representing a very efficient technique as an AOP method that has received much attention in recent years, assigned as a photoelectrochemical process. The process gained notoriety for the possibility of forming hydroxyl radicals via the oxidation of water. The technique is based on the action

separation is facilitated by applying a positive potential (EAPP), greater than the potential of a flat band photocatalytic material. The generation of a potential gradient in the photoactivat‐ ed semiconductor directs the electrons to an auxiliary electrode (cathode), delaying recombi‐

available for oxidation processes and the generation of hydroxyl radicals of interest [104]. The results of this process were very promising because of the relatively short treatment time but with great efficiency, both in the removal of color and in the reduction of the organ‐ ic load. However, the limitations of this technique are related mainly to the choice of the ide‐ al catalyst for promoting the generation of these oxidizing species. Catalysts that promote the generation of radicals absorbing radiation in the visible spectral region are the most de‐ sirable for this type of reaction, due to the large percentage emitted in the solar spectrum

Thus, the development of an ideal process that promotes color removal and a reduction in the organic load of wastewater from the textile industry with great efficiency is a major challenge in all fields of science, since the synthesis of the best catalyst to take advantage of solar radia‐ tion, thus reducing the operating costs, and at the same time solve the problems involved in the

The expectations for developing an effective method for the treatment of these wastes are quite promising, but require continuous optimization and knowledge of new aspects. These include better fixation of the dyes to the fibers, process with less water consumption, less hazardous dyes with respect to human health and methods capable of identifying these compounds with more efficacy and rapidity and assays to identify any potential carcinogen‐ ic and / or mutagenic properties in the dyes and their derivatives; genetic improvements to produce more efficient culture mediums and resistant biological treatments, leading to a re‐ duction in the generation of sludge; the synthesis of materials that catalyze reactions in the visible spectral regions, leading to a more economic photoeletrochemical method, and also new engineering advances for the construction of more effective reactors, which can take ad‐ vantage of all these developments in an integrated system, extending the performance of a

hydrodynamics of the reactors, is of importance in the development of the treatment.

process more appropriate for the treatment of such a complex effluent.

**5. Optimization of the dyeing processes to reduce the environmental**

The search and development of new methods to promote the treatment of effluents from the textile industry with a maximum of efficiency of the process of decolorization and / or re‐

) generated in the valence band (VB), and making them

/ H+

, whose

of ultraviolet light (hυ) on a semiconductor capable of generating charges and e-

nation between the holes (h+

166 Eco-Friendly Textile Dyeing and Finishing

(approximately 45%) [104].

**impact of the textile industry**

It was concluded that the synthetic textile dyes represent a large group of organic com‐ pounds that could have undesirable effects on the environment, and in addition, some of them can pose risks to humans. The increasing complexity and difficulty in treating textile wastes has led to a constant search for new methods that are effective and economically via‐ ble. However, up to the present moment, no efficient method capable of removing both the color and the toxic properties of the dyes released into the environment has been found.
