Azo Dye Aqueous Solution Research Articles

The Kinetic Model for Decolourization of Commercial Direct Blue 2 Azo Dye Aqueous Solution by the Fenton Process and the Effect of Inorganic Salts

The Kinetic Model for Decolourization of Commercial Direct Blue 2 Azo Dye Aqueous Solution by the Fenton Process and the Effect of Inorganic Salts

Fe78Si9B13 amorphous alloys for the decolorization process of azo dye aqueous solutions with different initial concentrations at different reaction temperatures

In this paper, amorphous Fe78Si9B13 ribbons were used to decolorize Acid Orange Ⅱ solutions with different initial concentrations at different temperatures. The effects of reaction temperature on the decolorization process were investigated, and the activation energies for the decolorization reaction in the temperature range of 25°C–50 °C were obtained based on the Arrhenius equation. It was found that the reaction temperature had different influence rules for dye solutions with different initial concentrations, and that the activation energies were significantly different for different initial concentrations. Higher temperatures were conducive to the decolorization of dye solutions especially high-concentration dye solutions, and low-concentration dye solutions generally required lower activation energies for the decolorization reaction. Our work provides experimental support for adjusting technical parameters in the remediation of dye wastewater to enhance the decolorization efficiency.

Highly efficient and stable CuZr-based metallic glassy catalysts for azo dye degradation

Metallic glasses with the unique disordered atomic structure and metastable nature have been recently applied to degrade the azo dyes and other organic pollutants based on their superior catalytic performance. In this work, the functional properties of six CuZr-based metallic glassy ribbons with the different nominal components in degrading Acid Orange Ⅱ (AO Ⅱ) azo dyes were investigated. The Cu47.5Zr46Al6.5 metallic glassy ribbons could exhibit the more advanced catalytic performance for degradation process, which could completely degrade azo dye aqueous solution within 30 min. Additionally, the Cu47.5Zr46Al6.5 metallic glassy ribbons also showed the excellent cyclic stability along with approximately 97.68 % degradation efficiency after 10 cycles. These excellent catalytic performance and stability are closely related to the synergistic effect of exposed copper nanoparticles and produced copper oxides in the reaction, which contributes to accelerate the generation of more hydroxyl radicals (·OH) to react with dye molecules. Our findings can be able to develop a novel potential metallic glassy material for the functional application of wastewater treatment.

Multi-functional MnO2 nanomaterials for photo-activated applications by a plasma-assisted fabrication route.

Supported MnO2-based nanomaterials were fabricated on fluorine-doped tin oxide substrates using plasma enhanced-chemical vapor deposition (PE-CVD) between 100 °C and 400 °C, starting from a fluorinated Mn(ii) diamine diketonate precursor. Growth experiments yielded β-MnO2 with a hierarchical morphology tuneable from dendritic structures to quasi-1D nanosystems as a function of growth temperature, whose variation also enabled a concomitant tailoring of the system fluorine content, and of the optical absorption and band gap. Preliminary photocatalytic tests were aimed at the investigation of photoinduced hydrophilic (PH) and solid phase photocatalytic (PC) performances of the present nanomaterials, as well as at the photodegradation of Plasmocorinth B azo-dye aqueous solutions. The obtained findings highlighted an attractive system photoactivity even under visible light, finely tailored by fluorine content, morphological organization and optical properties of the prepared nanostructures. The results indicate that the synthesized MnO2 nanosystems have potential applications as advanced smart materials for anti-fogging/self-cleaning end uses and water purification.

The Kinetic Model for Decolorization of Commercial Reactive Red 120 Azo Dye Aqueous Solution by the Fenton Process and Study the Effect of Inorganic Salts

The degradation of a commercial azo dye Reactive Red 120 (RR120) in synthetic aqueous solution using Fenton's oxidation has been studied. The influence of different reaction parameters such as pH, hydrogen peroxide, ferrous sulfate, and the RR 120 concentration on the oxidative degradation of RR 120 have been appraised. The optimal reaction conditions were determined and it was found to be pH = 3.50, [H2O2] = 1.1×10-3 M, [Fe2+] = 1.0×10-4 M for [RR 120] = 7.5×10-5 M. Under optimal conditions, 96.0% decolorization efficiency of dye in aqueous solution was achieved after 15 min of reaction. The effect of azo bond loading (Lazo bond), from 0.25 to 1.0, and pH values from 2.5 to 5.0 were estimated on RR 120 color removal kinetic rates. A correlation between the kinetic of the color removal rates (ln k2) versus Lazo bond was carried out at the different pH levels. The color removal rate increased linearly with decreasing Lazo bond, in the order of pH: 3.5 > 5.0 > 2.5. All the experimental data were analyzed using the first and second-order kinetic models. The second-order provides the best correlation of the data. 67% Chemical Oxygen Demand (COD) removal efficiency of the RR 120 were achieved after 15 min of reaction by fixing the initial H2O2/Fe2+ molar ratio, COD loading factor (LCOD), and pH at 11, 0.25 and 3.5, respectively. Also, the effects of various inorganic anions (such as Cl−, SO42-, CO32-, etc.) on the oxidation efficiency of Fenton were studied. This study can benefit planners who deal with contaminated textile wastewater using chemical treatment by advanced oxidation technologies.

Ozonation of Reactive Orange 4 dye aqueous solution using mesoporous Cu/SBA-15 catalytic material

The catalytic ozonation using mesoporous SBA-15 supported copper catalyst (Cu/SBA-15) was employed for the degradation of reactive orange 4 (RO4) azo dye in aqueous solution. The catalyst was synthesized and characterized using BET, SEM, TEM and EDX techniques. The characteristic results revealed highly ordered mesoporous structure, uniform pore sizes, parallel arranged channels and large surface area for the catalyst. The effects of copper loading on SBA-15, initial solution pH and ozone dose on the degradation of RO4 dye were studied. The complete colour removal from RO4 azo dye aqueous solution was obtained after 21 min of ozonation. The maximum TOC removal efficiency of 86% was obtained at optimum operational conditions of 2% copper loadings, initial solution pH 9 and ozone dose of 5 g/m3 after 60 min reaction time. The degradation pathway of catalytic ozonation reaction was studied by adding t-butanol as radical scavenger and it was found that the presence of radical scavenger had no effect on colour removal efficiency suggesting direct ozone molecular type mechanism. However, TOC removal efficiency was significantly reduced with the addition of t-butanol, thereby, indicating a hydroxyl radical based mechanism. The catalytic ozonation reaction followed pseudo-first order kinetics with respect to RO4 dye concentration. The reusability study for the catalyst suggested a negligible loss in the degradation efficiency after five runs of experiments. The stability of the catalyst was studied by performing leaching experiments which suggested that the catalyst has the potential to be utilized for the degradation of aqueous dye solution.

Comparison between the photocatalytic degradation of single and binary azo dyes in TiO2 suspensions under solar light irradiation

Textile industries discharge a large quantity of colored wastewater which is harmful to the ecosystem. In this study, two kinds of dyes were investigated: the mono azo Acid Orange 7 (AO7) and diazo Reactive Green 19 (RG19). The photocatalytic degradation of single (AO7, RG19) azo dye and binary (AO7 and RG19 mixture) azo dye aqueous solutions was photocatalyzed by commercial titanium dioxide (TiO2, P25) under solar light irradiation. The objectives of this study are to compare the photocatalytic degradation between single and binary azo dye aqueous solution and to study the various parameters such as the effect of different initial azo dye concentrations, different initial azo dye pH values, and compare the adsorption capacity of azo dyes with and without solar light irradiation, which influences the photocatalytic activities of single and binary azo dye aqueous solutions in a TiO2 suspension. The results showed that photocatalytic degradation of AO7 and RG19 in a single azo dye aqueous solution was faster than a binary azo dye solution under the solar light irradiation process. Chemical oxygen demand results revealed that complete mineralization could be achieved for both AO7 and RG19 azo dyes under solar light irradiation within 22 hours.

Degradation of acid scarlet 3R with CuO/SiO2 hollow sphere catalyst

Silica-supported copper catalyst materials have been synthesized via an incipient wetness impregnation. The resulting samples were characterized using X-ray diffraction (XRD) and Scanning electron microscope (SEM). The heterogeneous Fenton-like oxidation of reactive azo dye solutions by this catalyst was also investigated. The effects of various operating conditions on decolorization performance were evaluated, namely hydrogen peroxide dosage, initial pH, catalyst loading and initial dye concentration. The results indicated that by using 34 mmol/L of H2O2 and 6.0 g L-1 of the catalyst at 60°C, pH 3.5, 97% of decolorization efficiency was achieved within 90 min. CuO/SiO2 hollow sphere is shown a promising catalyst for degradation of azo dye aqueous solution by Fenton-like processes.

Degradation of an Azo Dye (Ponceau 4R) and Treatment of Wastewater from a Food Industry by Ozonation

Experiments for degradation of the extensively marketed Ponceau 4R dye in aqueous solution and for oxidation of raw wastewater from a confectionary industry have been carried out by using ozone. All the experiments were performed in a cylindrical semi-batch reactor at approximately 20 oC for 7200 s. A mass flow rate of 1.158 × 10−6 kg s−1 of ozone was continuously fed in the reactor. The pH of the azo dye aqueous solution (distilled water + Ponceau 4R) was always kept at approximately 5.8, while in the case of the raw wastewater the same factor was changed from 4.7 to 9.4 in two different experimental runs. Absorbance measurements at 508 nm show that the investigated azo dye found in the azo dye aqueous solution was completely degraded after only 600 s. At this initial period a substantial fall of TOC (Total Organic Carbon) (up to 45%) was noticed, but the rate was exponentially decreased at longer reaction times up to a TOC removal no higher than 60%. The ozonation was also responsible for reducing the apparent color of the raw wastewater to almost 10% of its initial value at the optimum pH (9.4 ± 1.5). The effect of pH was important on apparent color, but it had absolutely no influence on the kinetics results of COD (Chemical Oxygen Demand), which were kept constant over the entire period of reaction.

The effect of annealing on photocatalytic properties of nanostructured titanium dioxide thin films

The photocatalytic degradation of a non-biodegradable azo dye called (C.I. Direct 80, Red Sulphonyl 3BL) was investigated using TiO 2 thin films in aqueous solution under irradiation of a mercury lamp Philips (UV-C) light source. The effect of operational parameters, i.e., annealing temperature of thin film, substrate nature on which TiO 2 films were deposited, film thickness, pH of the solution, dye concentration, and irradiation time on the degradation rate of azo dye aqueous solutions was examined. Results show that the employment of efficient photocatalyst and the selection of optimal operational parameters lead to complete decolorization. The best conditions for maximum photocatalytic degradation were found to be pH 1 at 5 ppm concentration of dye over TiO 2 thin films deposited on glass substrate coated with indium-tin oxide having 350 nm thicknesses annealed at 550 °C. The samples are all in the complete anatase phase and the particle size is in nanometer scale which is confirmed by XRD pattern analysis.

Oxidation of commercial reactive azo dye aqueous solutions by the photo-Fenton and Fenton-like processes

This paper evaluates the degradation of two azo reactive dyes, C.I. Reactive Yellow 84 (RY84) and C.I. Reactive Red 120 (RR120) by photo-Fenton and Fenton-like oxidation. All experiments were performed on a laboratory scale set-up. The effects of different reaction parameters such as initial pH, contact time, effect of light and hydrogen peroxide concentrations on the oxidation of the dye aqueous solutions have been assessed. Effective system conditions were found to be pH of 3, hydrogen peroxide-to-iron molar ratio of 20:1 and UV or solar irradiation. The color removal efficiency at the optimum conditions during different Fenton-like processes was also evaluated. The results show that the color removal of RY84 after 15 min reaction time follows the decreasing order: solar/Fe(II)/ H 2O 2>UV/Fe(II)/ H 2O 2>UV/Cu(II)/Fe(III)/ H 2O 2>UV/Fe(III)oxalate/H 2O 2>UV/Fe(III)/ H 2O 2>dark/Fe(II)/ H 2O 2>solar/Fe(III)oxalat/H 2O 2>UV/H 2O 2>UV/Fe(II)=UV. During the same reaction period the relative order for RR120 removal rate was slightly different: solar/Fe(II)/ H 2O 2>UV/Fe(II)/ H 2O 2>UV/Fe(III)/ H 2O 2=UV/Cu(II)/Fe(III)/ H 2O 2>UV/Fe(III)oxalate/H 2O 2=UV/H 2O 2>UV. The toxic potential of the dye’s degradation was investigated by the bioluminescence test using the LUMIStox 300 instrument and results were expressed as the percentage inhibition of the luminescence of the bacteria Vibrio fisheri. Formate and oxalate, identified as fragmental oxidation products of investigated dyes, could also be detected after 15 min irradiation time.