Red GR Research Articles

Laccase immobilization on hierarchical micro/nano porous chitin/graphene oxide beads prepared via Pickering emulsion template for dye decolorization

Nowadays, the removal of dye molecules from water sources is a major environmental concern and challenge. Enzymatic degradation (biological) and adsorptive (physical) dye removal are considered to be the most effective dye removal techniques. Laccase catalysis is a reliable method to remove synthetic dyes from water to reduce environmental pollution, but free laccase has the disadvantages of low stability and non-reusability. In this study, stable Pickering emulsions were prepared using chitin (Ch) and graphene oxide (GO) composite solutions. Ch/GO composite aerogel beads with hierarchical porous structure were obtained by emulsion template method combined with freeze-drying, and then used for laccase immobilization and dye decolorization experiments. The results showed that the immobilized laccase had better thermal stability compared to the free enzyme, and it was found that the optimum pH of the immobilized laccase was 3.4 and the optimum temperature was 55 °C. In the cyclic decolorization experiments of acid Big Red GR, the decolorization rate of CH/GO-30 was maintained at 100% after 5 cycles of ABTS (2,2-biazo-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt) by enzyme catalysis and carrier adsorption synergistically. The preparation of Ch/GO composite aerogel beads by the Pickering emulsion template method is simple and green, without the use of surfactants, avoiding secondary pollution to the environment, and has potential industrial applications in the decolorization and biodegradation of dye wastewater.

Preparation and Characterization of Dyed Corn Straw by Acid Red GR and Active Brilliant X-3B Dyes.

Corn straw is a kind of biomass material with huge reserves, which can be used in plate processing, handicraft manufacturing, indoor decoration, and other fields. To investigate the dyeing mechanism of corn straw with different dyes, corn straw was pretreated and dyed with Acid Red GR and Brilliant Red X-3B. The dyeing properties and light resistance of the two dyes were analyzed by dyeing rate, photochromaticity, FTIR, SEM, and water-washing firmness. The results showed that the structure and stability of the dyes were the main factors which influenced fading. A bleaching pretreatment could remove the waxiness of the corn straw epidermis and increase the porosity on the surface of the straw, which accelerated the photochromic coloring of the corn straw skin. The corn straw dyed with both dyes had good light resistance, but the straw dyed with Reactive Brilliant Red X-3B had higher dyeing rate, brighter color, and higher photochromaticity than the straw dyed with Acid Red GR. FTIR and water-washing firmness showed that Acid Red GR mainly bound to lignin, while Reactive Brilliant Red X-3B mainly bound to cellulose, hemicellulose, and lignin in corn straw through covalent bonds, which increased the coloring rate.

Preparation of a Novel Chitosan Based Biopolymer Dye and Application in Wood Dyeing.

A novel chitosan-based biopolymer dye possessing antibacterial properties was synthesized by reaction of O-carboxymethyl chitosan and Acid Red GR. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), degree of substitution (DS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), X-ray diffraction (XRD), water solubility test, antibacterial property test, and dyeing performance, including dye uptake, color difference, and fastness. Results showed that the synthesized dye was combined by –NH3+ of O-carboxymethyl chitosan and the sulfonic group of Acid Red GR. According to the comprehensive analysis of XRD and water solubility, the introduction of the carboxymethyl group and acid dye molecule changed the structure of the chitosan from compact to loose, which improved the synthesized dye’s water solubility. However, the thermal stability of the synthesized dye was decreased. The antibacterial property of the poplar wood dyed with the synthesized dye was enhanced and its antibacterial rate, specifically against Staphylococcus aureus and Escherichia coli, also increased to a rate of more than 99%. However, the dye uptake of the synthesized dye was lower than that of the original dye. Despite this, though, the dyeing effect of the synthesized dye demonstrated better water-fastness, and light-fastness than the original dye. Therefore, the novel chitosan-based biopolymer dye can be a promising product for wood dyeing.

Adsorptive removal of anionic dyes from aqueous solutions using microgel based on nanocellulose and polyvinylamine

A novel nanocomposite microgel based on nanocellulose and amphoteric polyvinylamine (PVAm) was fabricated via a two-step method. Firstly, cellulose nanocrystal was oxidized by sodium periodate to yield dialdehyde nanocellulose (DANC). DANC was then used as a crosslinker to react with PVAm to obtain a pH responsive microgel with high density of free amine groups. The microgel was characterized using FTIR, XRD, AFM and elemental analysis. AFM images revealed that the nanocomposite was microspherical particles with a diameter ranging from 200 to 300nm. The microgel was found to be effective in anionic dye removal at acidic conditions. The adsorption isotherms for congo red 4BS, acid red GR and reactive light yellow K-4G fit well with the Sips model, and the maximum adsorption capacities were 869.1mgg−1, 1469.7mgg−1 and 1250.9mgg−1, respectively. The adsorption for these three anionic dyes all followed pseudo second order kinetics, indicating a chemisorption nature.

Amino-functionalized nanocrystalline cellulose as an adsorbent for anionic dyes

In this present work, amino-functionalized nanocrystalline cellulose (ANCC) was prepared by a process involving, (1) extraction of nanocrystalline cellulose (NCC) from fully bleached hardwood kraft pulp by sulfuric acid hydrolysis, (2) sodium periodate oxidation of NCC to yield the corresponding C-2/C-3 dialdehyde nanocellulose (DANC) and (3) grafting with ethylenediamine to obtain ANCC through a reductive amination treatment. Properties of DANC and ANCC were characterized by conductometric titration, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction and atomic force microscopy. It was found that the primary amine groups of ANCC (0.77–1.28 mmol g−1) increased with the increase of ethylenediamine dosage. The successful grafting was further evidenced by Kaiser test and FT-IR analysis. Zeta potential measurements showed that ANCCs were amphoteric, and their isoelectric points were between pH of 7–8. Chemical modifications of the cellulose nanowhiskers reduced the crystallinity but the initial cellulose I polymorph was retained. The cross-sectional dimension of nanowhiskers was slightly decreased from about 5–10 to 3–8 nm after the oxidation, and a better dispersibility was observed. ANCC sample was then applied as an adsorbent to remove anionic dyes in aqueous solutions. It demonstrated the maximum removal efficiency at acidic conditions. The acid red GR adsorption on ANCC fitted well with the Langmuir model, with a maximum theoretical adsorption capacity of 555.6 mg g−1. The adsorption of congo red 4BS, acid red GR and reactive light yellow K-4G followed pseudo second order kinetics, indicating a chemisorption nature.

Surface photo-discoloration and degradation of dyed wood veneer exposed to different wavelengths of artificial light

The surface of dyed wood is prone to discoloration when exposed to light irradiation which significantly decreases its decorative effect and shortens its service life. The influence of light wavelength exposure to the surface of dyed wood was investigated to study the effect on discoloration and degradation. Acid Blue V and Acid Red GR dyed wood veneers were subjected to light exposure with different wavelengths from the UV to visible region (254–420nm). Results showed that the surface discoloration of dyed wood was linearly related to lignin concentration and dyes degradation and the consequent transformation of chromophoric groups such as aromatic (CC) and carbonyl (CO) through methoxy reaction. The dyes, lignin and some active constituents were degraded severely, even at short exposures. Acid Blue V dyed wood exhibited greater discoloration than the Acid Red GR treatment. The reflectance and K/S absorption curve showed a hypochromic effect on the dyed wood surface. The dyes and wood chemical structure played a complex and combined role on the selective absorption of different wavelengths of light. The color change rate was apparent with 254nm exposure in the initial stages, but a greater discoloration rate occurred on the samples irradiated at 313 and 340nm than at 254 and 420nm with the time prolonged. The degradation rate and degree of discoloration correlated well with the light energy and wavelength.

Process Optimization and Characterization of Copper Oxide/Zeolite for Heterogeneous Catalytic Wet Oxidation of Dyeing Wastewater

Waste coal fly ash was used, as a cheap and handy material, to synthesize zeolite.The synthesized zeolite was then taken, as a carrier, to load CuO by dipping method for heterogeneous catalytic wet oxidation of acid bright red GR wastewater. The optimal process parameters of CuO loading were determined by orthogonal test. The comparison of XRD patterns of zeolite and CuO/zeolite displayed that CuO was successfully loaded on the zeolite.The SEM morphology of CuO/zeolite revealed that the cotton shape structure with more loose surface of CuO/zeolite was obtained compared with the SEM morphologies of fly ash and synthesized zeolite. The experimental results of water treatment showed that high CODCr and chroma removal rates of 88.27% and 99.97% were achieved by the prepared CuO/zeolite sample,respectively.

Process Modeling of CuO/Zeolite Preparation for COD<sub>C</sub><sub>r </sub>Removal from Acid Bright Red GR Wastewater

The study on CuO/zeolite preparation for CODr removal from acid bright red GR wastewater was carried out. The optimal process parameters,with zeolite/copper nitrate solution ratio of 1:4 g/mL, copper nitrate solution concentration of 1.0mol/L, calcining temperature of 400°Cand calcining time of 5 h, were determined by single test method .The CuO/zeolite prepared under the optimal conditions obtained high CODCr and chroma removal rates with more than 87%and 99,9%,respectively.The process model of CuO/zeolite preparation was established by response surface methodology. The model was proved to be reliable and accurate and its theoretical values were very close to the the actual test values with absolute relative errors ranged from 0.00% to 1.49%, which can be used to predict, adjust and control the process conditions of CuO/zeolite preparation for getting desired CODCr removal rate.

Study on the Dyeing Effects of Thick <i>Birch</i> and <i>Elm</i> Wood Veneer by Atmospheric Pressure Impregnation

The dyeing effects of atmospheric pressure impregnation method on thick Birch and Elm veneer under bleached and unbleached treatment were discussed in this paper, as well as the color changes and influencing factors analyzed by CIE(1976)L*a*b*color system. The results showed that it was feasible to dye the thick Birch veneer using red acid GR under unbleached treatment and both the color saturation and gloss met the requirements while disperse dyes were not suitable for the thick veneer because of the general results, poor penetration, and low uptake rate. The dyeing effect on Elm was not satisfactory so that it was not recommended as dyeing wood while its better material quality made it better for furniture.

Large-scale preparation of indium-based infinite coordination polymer hierarchical nanostructures and their good capability for water treatment

The removal of dyes in wastewater has been of much interest in the recent decades because dyes are stable, toxic and even potentially carcinogenic, and their release into environment causes serious environmental, aesthetical, and health problems. In the current work, indium-based coordination polymer particles (In-CPPs) have been fabricated via a facile solvothermal synthesis without any template or surfactant. In-CPPs are composed of hierarchical nanostructures assembled from abundant nanoplates with thickness of about 20nm. Owing to their high BET surface area and pore volume, In-CPPs exhibit excellent adsorption capability for Congo red with a maximum capacity of 577mgg−1, which was higher than that of most materials reported to now. In-CPPS can also be outstanding adsorbents for removing other dyes such as acid chrome blue K, brilliant red GR and brilliant green. Furthermore, after calcinations in air In-CPPs can be converted to morphology-preserved porous In2O3 products which can detect NOx gas in air at room temperature.

Adsorption properties of dodecylsulfate-intercalated layered double hydroxide for various dyes in water

Organic dyes are an important class of pollutants in wastewater, and it is necessary to find a broad-spectrum adsorbent that can effectively remove different kinds of organic dyes. Through the organic modification of layered double hydroxides (LDHs), the surface properties of the LDHs change from hydrophilic to hydrophobic, resulting in a greater affinity for organic pollutants. Dodecylsulfate-intercalated layered double hydroxide (LDHs-SDS) was prepared with a Mg/Al molar ratio of 2:1 using a co-precipitation method, and was characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The synthesized LDHs-SDS was used as an adsorbent to remove anionic (direct blue G-RB (DB), reactive yellow 4GL (RY), acid red GR (AR)), cationic (basic blue (BB)) and nonionic dyes (disperse red 3B (DR)) from aqueous solution. The sorption was found to be independent of pH from 5 to 10. The maximum removal capacities for DB, RY, AR, DR and BB were 707.76, 392.88, 137.33, 249.24 and 165.11mg/g, respectively, at 298K. The adsorption isotherm for AR fitted the Freundlich model well, and data for the other dyes fitted the Langmuir model. The sorption kinetics of all five dyes were well described by the pseudo-second-order model. After treating actual dye wastewater with LDHs-SDS, the results indicate that this could be a potentially effective adsorbent for dye effluent treatment.

Oxidation of Azo Dyes by H2O2 in Presence of Natural Pyrite

Pyrite, FeS2, is the most common sulfide mineral. The aim of this work was to assess the oxidative ability of H2O2 in presence of natural pyrite by employing reactive black 5, acid red GR, and cationic red X-GRL as model pollutants. The effects of H2O2 dosage, pyrite loading, and initial pH on reaction were investigated. The results reveal that natural pyrite-promoted H2O2 has a great activity in the decoloration of azo dyes. About 85 % of reactive black 5 and acid red GR can be removed within 10 min when 0.3 mM H2O2 and 0.3 g/L pyrite are used with initial pH values ranging from 6.32 to 6.96. The discoloration efficiencies are demonstrated to be less sensitive to the initial solution pH value. Approximately 90 % of discoloration for reactive black 5 and acid red GR can be achieved when initial pH value ranges from 2 to 10. Ion leaching experiments show that high levels of ferrous iron and sulfate can be detected when natural pyrite is added to dye solution alone. To gain an understanding of the reaction mechanism and the role of natural pyrite takes in these processes, techniques including scanning electron microscope, X-ray diffraction, and X-ray photoelectron were employed to characterize the solid sample and ion leaching experiments were also carried out. Results indicate that the determined high levels of ions have resulted from the dissolution of FeSO4·H2O formed on the surface of pyrite and the homogeneous Fenton reaction initiated by ferrous iron in presence of H2O2 is mainly responsible for the observed fast color removal rate.

Characteristics of Activated Sludge in an Anoxic Baffled Reactor

AbstractThis study characterized sludge from an anoxic baffled reactor (ABR) used to treat textile dyeing wastewater. The process was run over 150 days. On day 152, five sludge samples were collected from compartments 1–5 of the ABR and a set of captive tests was conducted to investigate their particle size distributions (PSDs), dye biosorption and biodegradation properties, and dehydrogenase activity (DHA). The results indicated that the PSD of the five sludge samples from the ABR were similar. Methylene blue biosorption to the sludge samples followed the pseudo‐second‐order kinetic model and the actual biosorption process was controlled by external and intraparticle diffusion, simultaneously. After the sludge samples were cultivated for 24 h, the acid red GR dye removal efficiencies were 59.5, 68.3, 76.4, 61.5, and 65.4%, respectively. Eliminating dye biosorption, the dye biodegradation efficiencies were only 38.8, 46.3, 52.6, 48.3, and 46.0%, respectively. Furthermore, the DHA values were 28.2, 45.3, 56.5, 41.0, and 35.0 µg TF mL−1 h−1, respectively, and the DHA variation was in accordance with the dye biodegradation efficiency variation.

Influence of dye type and salinity on aerobic decolorization of azo dyes by microbial consortium and the community dynamics

In this research, aerobic decolorization of different azo dyes by a microbial community was studied. The results showed that more than 80% of four azo dyes (100 mg/L) could be aerobically decolorized by the microbial consortium, however, the time needed was obviously different. Kinetic data indicated that the processes were well described by zero-order kinetics, and the chemical structures of dyes had obvious influence on decolorization rates. On the other hand, effects of salinity on decolorization were also investigated. There was still 40% dye removal for Acid Brilliant Red GR when the salinity increased to 250 g/L. And the microbial community structures with different salinity were detected by PCR-DGGE. It was shown that the same two bacteria were dominant in all decolorization systems, and some typical halophilic microorganisms were found under higher-salt conditions.

Preparation of Copper Oxide Loaded Activated Carbon by Waste Sawdust for Acid Red GR Wastewater Treatment

The waste wood dust was utilized to prepare the copper oxide loaded activated carbon for the treatment of the printing and dyeing wastewater (acid red GR wastewater). The response surface assisted with Design-Expert 7.0 software was used to optimize the process. The secondary multiple regression models for the color and COD removal rates were established and proven to be significant. The optimum process conditions determined by the software were: copper nitrate (0.5mol/L) 15mL, ratio of liquid to solid 56, activation temperature 690 °C and activation time 2.1h, under which the color and COD removal rates reached 99.8% and 88.34%, respectively.

Synthesis of Coal Fly Ash Zeolite with Copper Oxide Load for Acid Red GR Wastewater Treatment

The waste coal fly ash was utilized to synthesize zeolite by alkaline fusion method through orthogonal test. The copper oxide was loaded on the zeolite by dipping method. The optimal ratio of coal fly ash to sodium hydroxide, ratio of liquid to solid, calcining temperature and crystallization time were determined to be 1.2, 9, 700°C and 10 h, respectively. The CuO dipped zeolite was applied to treat the acid red GR wastewater and the obtained color and COD removal rates were 83.80% and 99.88%, respectively. The XRD pattern showed that the NaA type zeolite phase was formed in the experiment.

Treatment of Dyeing and Printing Wastewater by Copper Oxide Loaded on Coconut Shell Activated Carbon

The activated carbon loaded copper oxide catalyst was prepared from Hainan abandoned coconut shells using chemical activation method and applied in treatment of acid bright red GR simulation dyeing wastewater. The effects of phosphoric acid concentration, ratio of liquid to solid, activation time and activation temperature on the COD and color removal rates were investigated by orthogonal experiment. The results showed that the optimal values of the parameters above were 65% (in mass), 3:1, 2.5h and 500°C under the designed copper oxide loading conditions of calcining temperature 300°C,calcining time 3.0 h and use level of copper nitrate 15 mL. Using the prepared sample for the treatment of the wastewater, the COD and color removal rates reached 94.384% and 99.840%, respectively.

Regeneration of CuZnO<sub>x</sub>/γ-Al<sub>2</sub>O<sub>3</sub> as a Heterogeneous Catalyst in CWPO Process

This paper evaluates the catalytic effectiveness of CuZnOx/γ-Al2O3 catalyst for the degradation of an azo dye, acid red GR, using H2O2 as an oxidant, under very mild conditions (atmospheric pressure and t = 40 ). In the catalytic wet peroxide oxidation (CWPO) process, the results show that it is possible to remove 80% of COD during the initial 30 h. But a considerable drop of catalytic activity is found after prolonged run. As characterization datas shown, the deactivation of the catalyst is caused by the depositon of intermediates on the surface and serious coverage of the active sites. However, calcination method which is possible to burn the organic species that trapped in the catalyst reaches complete restoration of the spent catalyst.

Influence of Different Wave-Lengths Artificial Light on Surface Discoloration of Dyed Veneer

Dyed Wood is rapidly degraded by short-wavelength UV radiation, and its degree of discoloration correlate well with the wave length. In the paper we test this hypothesis and analyze chemical change of dyed wood surface affected by UV radiation. So that it will be beneficial for further study on synthesis of photo stabilizer. In this research, dyed veneers are irradiated by artificial light using an ultraviolet accelerated weathering device including 5 different wavelengths (UV to visible). CIE (1976) L*a*b* color measuring system is applied to describe the photo-induced discoloration process of dyed veneer. The reflection curves of spectrum and K-M difference spectra show the diverse change of light absorption and reflection. The results reveal that, samples color is great influenced by 313nm and 340nm UV light, the color stability of dye stuffs is rapidly decreased while stimulated by 254nm UV light. The fastness of dyed veneer has a positive relationship with dye stuffs, Acid Red GR dyed veneer just suffer slight yellowing due to the stability of dye, while Acid Blue V dyed veneer fade obviously and get a tendency of reddish.

Biodecolorization of Acid Red GR by a newly isolated Dyella ginsengisoli LA-4 using response surface methodology

Decolorization of Acid Red GR by a newly isolated biphenyl-degrading bacterium, Dyella ginsengisoli LA-4 was presented in this paper. The optimal decolorization conditions were determined by response surface methodology (RSM) based on the rotatable central composite design. The results indicated that strain LA-4 possessed the highest decolorizing activity under anaerobic conditions with inoculation amount 6.49%, pH 7.06 and temperature 29 °C. Some ions such as Cu 2+, Zn 2+ could inhibit the decolorization, whereas 1 mmol/L of Mg 2+, Ca 2+, Co 2+, Fe 3+, Ni 2+ and Mn 2+ had no effects on the process. It was demonstrated that anthraquinone as a redox mediator could significantly accelerate the reduction process of azo dyes.