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Effluents with dyes when released into the environment can cause damage to ecosystems, preventing access to light and thus harming various environmental processes. Thus, the aim of the present study was to carry out a literature review on the use of heterogeneous photocatalytic processes based on double lamellar hydroxide (HDL)- TiO2 composites in the treatment of wastewater with dyes. Currently, the main means for the treatment of dyes is the use of physicochemical adsorption processes, however, some dyes have high stability in the medium, making it difficult to remove them without the use of advanced processes. Advanced oxidative processes (AOPs) emerge as an effective alternative due to their high redox potential, where heterogeneous photocatalysis using TiO2 has advantages due to its excellent photocatalytic activity, lower toxicity and costs compared to other available semiconductors. Among the challenges of this process is the low adsorptive potential of TiO2, due to its low area and porosity, thus, the incorporation in clayey supports, such as hydrotalcite, becomes a possibility to improve the properties of the semiconductor and thus improve the photocatalys process. [ABSTRACT FROM AUTHOR]

Various dyes are used in the textile industry. Azo dyes, stable and toxic, constitute the majority of these dyes. In this study, the removal of Astrazon Black MBL belonging to azo group with an innovative adsorbent was investigated. The efficiency of adsorbent was evaluated in terms of color removal, oxidation and reduction potential (ORP), FTIR (Fourier Transform Infrared Spectrometer), pH and ion count, and the results were optimized with Taguchi method. As a result of the study, color removal efficiency in the range of 98.4%-99.6% was obtained with the innovative adsorbent used. The pH and ORP of the liquid products after adsorption was measured in the range of 6.10-6.89 and in the range of 18.1-64.2 mV, respectively. From FTIR analysis results, Astrazon Black MBL dye was observed to be very stable. As a result, it was observed that waste can be evaluated successfully with adsorbent used in the study. In addition, since the adsorbent used does not have a cost, it provides the applicability of the method in terms of cost because the operating cost is low. [ABSTRACT FROM AUTHOR]

• synthesized a novel composite catalyst, NaNb x Ta 1−x O 3 /g-C 3 N 4. • degraded 99.6% of Methylene blue in 180 min under a 250 W Hg lamp. • Z-scheme heterojunction suppressed the recombination of the photogenerated carriers. • Z-scheme heterojunction protected the high redox potentials of both components. Water pollution has received much attention and constructing efficient catalysts to photodegrade the pollutants is a promising method. Herein, we reported that a novel composite catalyst, NaNb x Ta 1−x O 3 /g-C 3 N 4 , exhibited high efficiency to degrade the model pollutant, methylene blue (MB), in ultraviolet light. The optimal catalyst was NaNb 0.75 Ta 0.25 O 3 /g-C 3 N 4 (1:9), which degraded 99.6% of MB (10 mg/L) after 180 min of reaction. The superior photocatalytic activity was attributed to the formation of the Z-scheme heterojunction, which could suppress the recombination of the photogenerated electron-hole pairs and protect the high redox potentials simultaneously. Hydroxyl radicals (. OH) and superoxide radicals (. O 2 -) were found to be the dominant active free radicals in the reaction process and a possible photocatalytic mechanism over the catalyst was proposed accordingly. This work provides an efficient direction to fabricate composite photocatalysts and helps to overcome the shortcomings of a single catalyst. [ABSTRACT FROM AUTHOR]

The history of colour is fascinating from a social and artistic viewpoint because it shows the way; use; and importance acquired. The use of colours date back to the Stone Age (the first news of cave paintings); colour has contributed to the social and symbolic development of civilizations. Colour has been associated with hierarchy; power and leadership in some of them. The advent of synthetic dyes has revolutionized the colour industry; and due to their low cost; their use has spread to different industrial sectors. Although the percentage of coloured wastewater discharged by the textile; food; pharmaceutical; cosmetic; and paper industries; among other productive areas; are unknown; the toxic effect and ecological implications of this discharged into water bodies are harmful. This review briefly shows the social and artistic history surrounding the discovery and use of natural and synthetic dyes. We summarise the environmental impact caused by the discharge of untreated or poorly treated coloured wastewater to water bodies; which has led to physical; chemical and biological treatments to reduce the colour units so as important physicochemical parameters. We also focus on laccase utility (EC 1.10.3.2), for discolouration enzymatic treatment of coloured wastewater, before its discharge into water bodies. Laccases (p-diphenol: oxidoreductase dioxide) are multicopper oxidoreductase enzymes widely distributed in plants, insects, bacteria, and fungi. Fungal laccases have employed for wastewater colour removal due to their high redox potential. This review includes an analysis of the stability of laccases, the factors that influence production at high scales to achieve discolouration of high volumes of contaminated wastewater, the biotechnological impact of laccases, and the degradation routes that some dyes may follow when using the laccase for colour removal [ABSTRACT FROM AUTHOR]

• Vinasse produced during distillation of the alcohol pisco an environmental hazard. • Pisco vinasse has high polyphenols contents and chemical oxygen demand (COD). • AOP treatments evaluated: UV, US, heterogeneous photocatalysis (HP), UV + US, HP + US. • HP + US best for polyphenols, COD, and color removal, but US most energy efficient. • High pollutant-removal + energy efficiency make US practical pisco vinasse treatment. Production of the distilled alcohol pisco results in vinasse, dark brown wastewater with high polyphenols contents and chemical oxygen demand (COD). No prior research exists on the efficiency of advanced oxidations processes (AOPs) in treating pisco vinasse. Therefore, the purpose of this study was to assess the efficiency of ultraviolet (UV), ultrasound (US), US + UV, heterogeneous photocatalysis (HP), and HP + US treatments. Polyphenols, COD, and color removal, as well as oxidation-reduction potential, were monitored over a 60-minute treatment period. Energy consumption levels and synergies were also calculated. The HP + US treatment achieved the best removal ratios for polyphenols (68%), COD (70%), and color (48%). While the HP treatment was the second most efficient in terms of polyphenols (62%), COD (58%), and color (40%) removal, this AOP comparatively required the least amount of energy. Considering the energy efficiency and relatively high pollutant-removal rates of the HP treatment, this AOP is recommended as a practical alternative for treating pisco vinasse. [ABSTRACT FROM AUTHOR]