Spectroscopic Studies on Interaction of Congo Red with Ferric Chloride in Aqueous Medium for Wastewater Treatment

Absorption spectroscopic studies of Congo red (CR) in interaction with FeCl₃ in aqueous medium have been reported in this article. The interaction of CR with FeCl₃ has been investigated with an aim to explore a possible low cost and efficient way to remove CR from industrial waste water. The removal mechanism is based on the formation of a complex of iron with anionic part of the CR molecule in interaction with FeCl₃. An exceptionally high removal rate of 2670 mg/g has been observed at 100 mg/L initial CR concentration and enhanced removal rate was found with increasing initial CR concentration.     

Electrochemical oxidation of acid black 210 dye on the boron-doped diamond electrode in the presence of phosphate ions: Effect of current density, pH, and chloride ions

The electrochemical oxidation of acid black 210 dye (AB-210) on the boron-doped diamond (BDD) was investigated under different pH conditions. The best performance for the AB-210 oxidation occurred in alkaline phosphate solution. This is probably due to oxidizing agents such as phosphate radicals and peroxodiphosphate ions, which can be electrochemically produced with good yields on the BDD anode, mainly in alkaline solution. Under this condition, the COD (chemical oxygen demand) removal was higher than that obtained from the model proposed by Comninellis. Electrolyses performed in phosphate buffer and in the presence of chloride ions resulted in faster COD and color removals in acid and neutral solutions, but in alkaline phosphate solution, a better performance in terms of TOC removal was obtained in the absence of chloride. Moreover, organochloride compounds were detected in all electrolyses performed in the presence of chloride. The AB-210 electrooxidation on BDD using phosphate as supporting electrolyte proved to be interesting since oxidizing species generated from phosphate ions were able to completely degrade the dye without producing organochloride compounds.     

Sorption studies of neutral red dye onto poly(acrylamide‐co‐maleic acid)‐kaolinite/montmorillonite composites

In this study, a procedure for preparation of organic–inorganic composite was established. The procedure was based on gamma irradiation polymerization of polyacrylamide (PAAm) in presence of maleic acid (MA), clay minerals [kaolinite (K)], or [montmorillonite (M)] and methylenebisacrylamide (NMBA) as a crosslinker. The functionality of the produced adsorbents were assayed using FTIR spectroscopy, SEM, and XRD and were evaluated for sorption of neutral red (NR) dye from aqueous solutions via batch sorption experiments. Various factors influencing the sorption behavior (e.g., pH, sorbent dose, and dye concentration) were studied. The sorption data fitted well with Langmuir isotherm model. Batch kinetic experiments showed that the adsorption followed pseudosecond‐order kinetic model with correlation coefficients greater than 0.999. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of photocatalytic La(1-x)AxTiO3.5-δ(A=Ba,Sr, Ca) nano perovskites and their application for photocatalytic oxidation of congo red dye in aqueous solution

A-site substituted La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nano perovskites were prepared by sol-gel method and characterized using thermogravimetry/differential thermal analysis(TGA/DTA), X-ray diffraction(XRD), ultraviolet-visible(UV-Vis) spectroscopy and transmission electron microscopy(TEM). XRD analysis showed that the La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nano perovskites derived after calcination at 800 oC were in single phase with orthorhombic structure. The particle size of all nano perovskites was found to be ~20 nm. The synthesized nano perovskites were tested for the photocatalytic decomposition of an azo dye, Congo red. The sequential behavior of La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nanoperovskites for photocatalytic decomposition of congo red in aqueous solution by visible light at room temperature was studied at various time intervals and the efficiency of degradation of the nanoperovskites was compared. Among all the A-site substituted La0.8A0.2TiO3.5–δ(A=Ba, Sr, Ca) nano perovskites, Ba substituted compound showed the highest dye degradation.     

B型活性染料在人造棉织物印花上的应用探讨

本针对B型活性染料对人造棉织物印花工艺进行探讨，提出了各工艺加工中的控制要点，达到减少印花庇病，提高产品质量的目的。     

Mordant dyes as sensitisers in dye-sensitised solar cells

Many mordant dyes commonly used in the textile industry form coordination complexes at the surface of nanocrystalline TiO₂. Dyes having a salicylate chelating group are particularly effective. Forty-nine commercial mordant dyes were studied as sensitisers in a non-optimised dye-sensitised solar cell (DSSC) and their performance compared to the N3 ruthenium complex. Although N3 produced the highest output, six mordant dyes produced photocurrents >0.2 mA. UV–visible spectra of the dye-complexed photoanodes suggest that some mordant dyes are more strongly bound to the TiO₂ surface than N3. Photocatalytic oxidation of these dyes does not appear to occur in a DSSC environment.     

Self-organized dye particles: Role of dewetting process in molecular ordering

Self-organized rhodamine 6G particles prepared by wetting/dewetting process of an ethanol solution on a hydrophilic glass surface exhibited fluorescence without quenching, showing a sharp linewidth of 2 nm with a large redshift, which indicates an existence of dye aggregates, similar to J aggregates, inside the particle. Polarized evanescent field excitation showed that the dye molecule's transition moment along the π-conjugation was oriented unidirectionally within particles and parallel to the substrate surface. This deduced dye orientation showed correlation between adjacent, however separated, particles, and pointed roughly 45° off the dewetting direction. In contrast, another π-conjugated NK1420 dye, J aggregates of which grow easily from an oversaturated solution, yielded particles with constituent dyes oriented along the dewetting direction preferably, still indicating the effect of self-organization, however based on a different mechanism.     

腈纶胶用作活性染料印花原糊的研究

腈纶纺丝下脚及废丝经烧碱水解,其中腈基水解成酰胺基及羧基,形成高分子电解质,再经部分交联,使含固量降低,可用作活性染料的印花原糊.文章就变形腈纶胶与活性染料的反应性、印花给色量、可洗性、流变性、含固量的降低等方面进行研究,证明变性腈纶胶完全可以取代海藻酸钠糊作为活性染料的理想印花原糊。     

Decolorization,mineralization, and toxicity reduction of acid orange 6 by iron‐sacrificed plates in the electrocoagulation process

In this study, electrocoagulation (EC) was used to investigate the decolorization and mineralization of an azo dye solution, as well as biodegradation enhancement and toxicity reduction. Initial pH, flow rate, and acid orange 6 concentration were investigated, and the optimum operational parameters were found to be pH = 4, flow rate (Q) = 0.3 to 0.5 L min^?1, and current density = 68.3 A dm^?2. With these optimal parameters, total organic carbon and color removal efficiencies of 40% and 98% were achieved, respectively. Biodegradation was evaluated using the ratio of the 5‐day biological oxygen demand (BOD₅) and the chemical oxygen demand (COD), which was 0.19 to 0.25 initially and increased to the range 0.25 to 0.4 after EC treatment, indicating that biodegradability was significantly enhanced. The mean effective concentration (EC₅₀) was measured to represent the toxicity of the solution. Initial EC₅₀ values ranged from 25 to 6.6%, which represent extremely toxic to very toxic solutions. After EC treatment, the toxicity levels were reduced significantly, suggesting that the EC process could be a promising method for reducing the toxicity of textile wastewater. Copyright © 2007 Society of Chemical Industry