Degradation of a textile reactive azo dye by a combined biological-photocatalytic process: Candida tropicalis Jks2 -Tio2/Uv

Abstract

In the present study, the decolorization and degradation of Reactive Black 5 (RB5) azo dye was investigated by biological, photocatalytic (UV/TiO2) and combined processes. Application of Candida tropicalis JKS2 in treatment of the synthetic medium containing RB5 indicated complete decolorization of the dye with 200 mg/L in less than 24 h. Degradation of the aromatic rings, resulting from the destruction of the dye, did not occur during the biological treatment. Mineralization of 50 mg/L RB5 solution was obtained after 80 min by photocatalytic process (in presence of 0.2 g/L TiO2). COD (chemical oxygen demand) was not detectable after complete decolorization of 50 mg/L RB5 solution. However, photocatalytic process was not effective in the removal of the dye at high concentrations (≥200 mg/L). With 200 mg/L concentration, 74.9% of decolorization was achieved after 4 h illumination under photocatalytic process and the absorbance peak in UV region (attributed to aromatic rings) was not completely removed. A two-step treatment process, namely, biological treatment by yeast followed by photocatalytic degradation, was also assessed. In the combined process (with 200 mg/L RB5), absorbance peak in UV region significantly disappeared after 2 h illumination and about 60% COD removal was achieved in the biological step. It is suggested that the combined process is more effective than the biological and photocatalytic treatments in the remediation of aromatic rings.

Phytoremediation: Potential flora for synthetic dyestuff metabolism

“…Moreover, chromophoric groups of dyes strongly absorb sunlight thereby inhibit the photosynthetic activity of phytoplanktons including aquatic plants and algal species by preventing light penetration (Abo-Farah, 2010;da-Silva et al, 2010;Kagalkar et al, 2010). Thus, apart from destroying natural quality of water bodies, these dyes also threaten aquatic biota such as flora and fauna by disturbing the ecological balance and posing serious environmental concerns, hence need to be treated or removed prior to their disposal or dispersal into water bodies or surrounding environment (Manu and Chaudhari, 2003;Zille et al, 2004;Kornaros and Lyberatos, 2006;Sudarjanto et al, 2006;Abo-Farha, 2010;Jafari et al, 2012).…”

A comparison investigation on photocatalytic activity performance and adsorption efficiency for the removal of cationic dye: Quantum dots vs. magnetic nanoparticles

“…A negligible decrease in DE% at high concentration of VBR may be attributed to some reasons. At a high dye concentration, a significant amount of UV may be absorbed by the dye molecules rather than the nanoparticles, known as the inner filtration effect, and thus reduce the efficiency of the catalytic reaction [17]. Moreover, the high concentration of dye would have acted as a filter for the incident light, which ultimately reduced degradation efficiency [53].…”

“…Some of the methods for removal of pollutants from wastewater are adsorption [7] membrane separation [8], catalytic ozonation [9], Fenton [10], electro-Fenton [11], advanced oxidation process [12,13], electrochemical degradation [14], photocatalytic degradation [15][16][17] biodegradation [18], and ultrasonic irradiation [19]. These methods have their own advantages and disadvantages.…”

Intimately coupling of photolysis accelerates nitrobenzene biodegradation, but sequential coupling slows biodegradation

“…Among them, UV photo(cata)lysis is relatively easy to couple with biodegradation [4][5][6], and it has been successfully used with a range of recalcitrant organic compounds [3,7].…”