Decolorization Of Dye Effluents Research Articles

N-myristoyltaurine capped copper nanoparticles for selective colorimetric detection of Hg2+ in wastewater and as effective chemocatalyst for organic dye degradation

The discharge of organic dyes and hazardous heavy metals from diverse industries into the environment has become a serious problem. Herein, we report that N-myristoyltaurine capped copper nanoparticles (CuNPs) speeds up the decolorization of dye effluents in the presence of sodium borohydride (NaBH4). The decolorization followed by UV–visible spectroscopy revealed that the reaction follows pseudo first-rate kinetics. All the tested dyes decolorized in less than 3 min. As a result of decolorization, the toxicity of the dye effluents decrease considerably, which was proved by seed germination assay. Further, the surface plasmon resonance property of the CuNPs was explored for selective and sensitive detection of hazardous mercury ions in sewage water (SW) and artificial cerbospinal fluid (aCSF). In the presence of Hg2+, galvanic displacement reactions promote the aggregation and the color change of CuNPs from wine red to grayish white. On the basis of colorimetric change, a minimum concentration of 15 μM of Hg2+ can be detected by the naked eye. The spectrophotometric detection method showed a detection limit of 0.1125 μM. Interference studies suggest that CuNPs is highly sensitive to Hg2+ ions. Recovery experiments proved that CuNPs quantitatively detect the spiked Hg2+ ions in tap water, SW and aCSF with an acceptable recovery range of 92 to 113%. Overall, the experimental outcomes suggest that the CuNPs could be deployed as a catalyst to decolorize dye effluents and as a colorimetric probe for mercury detection in wastewater.

Comparison of Alkali-Tolerant Fungus Myrothecium Sp. IMER1 and White-Rot Fungi for Decolorization of Textile Dyes and Dye Effluents

A new isolated nonligninolytic fungus, strain Myrotheciumsp. IMER1, was found to decolorize five different synthetic dyes when grown on dye-containing agar plates. The capability of Myrothecium sp. IMER1 for decolorization of Remazol Brilliant Blue R (RBBR) and dye effluents was compared with that of five white-rot fungi. More than 65% RBBR removal by Myrotheciumsp. IMER1was observed at various pHs (5-10). About 60-95% of decolorization was observed with these white-rot fungi in the acidic pH range of 5.0-6.0, whereas color removal rate was less than 30% in the basic pH range of 8.0-10.0. Myrothecium sp. IMER1 had a more efficient decolorization of the dye in a broad pH range than white-rot fungi tested. In comparison with color removal performance, Myrotheciumsp. IMER1 was approximately 2-5-fold better than white-rot fungi tested in the basic pH range. Additionally, the visual observation and Ultraviolet-Visible (UV-VIS) spectral analysis demonstrated that decolorization of dye by Myrothecium sp. IMER1 was due to biodegradation and biosorption. Biomass production was not affected by changes in the pH range of 7-10, indicated that Myrothecium sp. IMER1 is alkali-tolerant fungus. Decolorization of dye effluents by Myrothecium sp. IMER1 at pH 7 and 9 was 73 and 70%, respectively, while less than 25% of decolorization was observed in the case of white-rot fungi tested. Our results showed that Myrothecium sp. IMER1 exhibited efficient decolorization of dye effluents comparedtowhite-rot fungi, indicatingthat the alkali-tolerant strain Myrothecium sp. IMER1 will be potential candidates for wastewater treatment of dye effluents, especially alkaline dye effluents.

Oxidative decolorization of triphenylmethane dyes by chloramine-T in alkaline medium catalyzed by Pd(II): A comparative spectrophotomeric kinetic and mechanistic approach

Triphenylmethane dyes viz., p-rosaniline, crystal violet and ethyl violet (henceforth abbreviated as Dye) have been extensively used as colorants in textile industries. Effluents containing these dyes released by the industry causes significant environmental problems. Hence decolorization of dye effluents has acquired increasing attention. The oxidative decolorization of these dyes is of greater significance one understanding of their kinetic and mechanistic aspects in redox reactions is important. Consequently, Pd(II) catalyzed kinetics and oxidative decolorization of p-rosaniline, crystal violet and ethyl violet dyes by chloramine-T (CAT) in NaOH medium were studied spectrophotometrically. The oxidation reaction follows the identical kinetics for all the three dyes and obeys the rate law: rate = k[CAT] a [Dye] b [OH −] c [Pd(II)] d where a and b are unity, and c and d are less than unity. Addition of p-toluenesulfonamide, the reduction product of CAT, retards the rate and the order was found to be less than unity. The reaction rate increased with increasing ionic strength of the medium. Addition of chloride ions show negligible effect on the rate of reaction. Oxidation products were characterized by GC–MS analysis. Proton-inventory studies with ethyl violet as a probe have been made in H 2O–D 2O mixtures. Activation parameters and decomposition constants have been deduced. An isokinetic relation is observed with β = 423 K indicating enthalpy as a controlling factor. The rate of oxidation of triphenylmethane dyes follows the order: p-rosaniline > crystal violet > ethyl violet. This trend may be attributed to inductive effects of alkyl amino groups. Further, the kinetics of Pd(II)-catalyzed oxidation of these dyes have been compared with uncatalyzed reactions (in the absence of Pd(II) catalyst) and found that the catalyzed reactions are nearly four times faster. The catalytic constant ( K C) for Pd(II) was also calculated for each dye at different temperatures and the values of activation parameters with respect to the catalyst have been evaluated. Chlorite ion (OCl −) has been postulated as the reactive oxidizing species. The observed results have been explained by a general mechanism, and the related rate law has been obtained. Furthermore, the simple and elegant method developed for the decolorization of triphenylmethane dyes in the present work can be adopted for treating the aforesaid dyes present in industrial effluents to minimize the toxicity caused by these dyes.