Textile industry consumes considerable amounts of water during various processes such as dyeing. The existence of color and aromatic rings in the form of aromatic amines in textile wastewater is a very important problem. In this paper, photocatalytic decolorization and aromatic ring degradation of Direct Red 80 in a fixed bed photocatalytic reactor, utilizing a very simple analytical method, direct UV–vis spectrophotometric detection, has been investigated. Photocatalytic decolorization and aromatic ring degradation processes performed using a 5l solution containing Direct Red 80. The initial concentration of Direct Red 80 was 50mgl−1. The radiation source was two 15W UV-C lamps. A batch mode immersion photocatalytic reactor was utilized. The effect of variables such as pH and H2O2 concentration were studied. Bench scale simulated colored textile wastewater was completely decolorized in a relatively short time after UV irradiation with a low concentration of hydrogen peroxide. The lack of any absorbance in the UV–vis spectra was indicative of the complete aromatic ring degradation. Kinetics analysis indicates that the dye photocatalytic decolorization rates can usually be approximated pseudo-first-order model. UV/TiO2/H2O2 process proved capable of the complete degradation of the Direct Red 80.
The current investigation has utilized a simple and constructive stratified method to synthesize a binary (Cs/Z-8: chitosan (Cs) and zeolitic imidazolate framework-8 (Z-8)) and ternary Cs/Z-8/Z-67 (Z-67: ZIF-67) biocomposites at room temperature. A certain amount of Cs/Z-8 (0.05, 0.1, and 0.2 g) was used to prepare ternary biocomposites (denoted as Cs/Z-8/Z-67-0.05, Cs/Z-8/Z-67-0.1, and Cs/Z-8/Z-67-0.2, respectively). The synthesized materials were characterized. Through the adornment Cs, a non-toxic biopolymer, with Z-8 and Z-67, the desired efficacy in removing pollutants (TCN: Tetracycline, AB92: Acid Blue 92, and MB: Methylene Blue) was achieved under LED visible light. TCN removal in the presence of visible light by Cs, Z-8, Cs/Z-8, Cs/Z-8/Z-67-0.05, Cs/Z-8/Z-67-0.1, and Cs/Z-8/Z-67-0.2 was 22.6 %, 47.3 %, 69.0 %, 77.0 %, 95.5 %, and 65.0 %, respectively. The trapping test showed that TCN degradation by adding ascorbic acid, methanol, and IPA was 44.8 %, 66.9 %, and 78.5 %, respectively. It could be concluded that the O2 – play the decisive role for the destruction of TCN. The reusability of Cs/Z-8/Z-67-0.1 as a photocatalyst indicated that it had the capability to preserve its stability and performance for three successive cycles of use (95.5 %, 89.0 %, and 84.0 %). Also, Cs/Z-8/Z-67 had dye degradation ability (39.0 % for Methylene Blue and 81.0 % for Acid Blue 92).
This paper presents photocatalytic decolorization, computational fluid dynamics (CFD) modeling of decolorization and mineralization of textile dyes, Astrason Blue FGGL (AB) and Solophenyl Yellow FFL (SF), by photocatalysis using immobilized titania nanoparticle. UV-Vis spectrophotometry, Ion chromatography (IC) and total organic carbon (TOC) analyses were employed to obtain the details of the photocatalytic decolorization and mineralization of AB and SF. The CFD model was used to solve the mathematical equation describing decolorization process numerically taking into account finite volume descretization scheme. The CFD model predictions were compared to those results obtained from experimental tests for the decolorization of dyes by photocatalysis and close agreement was achieved. Ninety-five percent total organic carbon of both dyes can be eliminated after 240 min of irradiation time.
The functionalized copper oxide–zinc oxide nanocomposite (FCZN) was synthesized and characterized using Fourier transform infrared, scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and BET. Dye removal from aqueous solution was done in a batch system using FCZN as an adsorbent. The effects of adsorbent dosage, initial dye concentration, pH, temperature, and additive salts on dye removal were investigated. Isotherms, kinetics, and thermodynamics of dye adsorption were studied. Equilibrium and kinetic data were fitted by Langmuir isotherm and pseudo-second-order kinetic, respectively. The thermodynamic data showed that dye adsorption was spontaneous, endothermic, and physical reaction. In addition, genetic programming (GP) was applied in order to predict dye removal using an explicit formula. The results of proposed GP models were in close agreement with the experimental data.
Herein, Zeolitic imidazole framework-8 (ZIF-8) as a 3D nanoporous support was synthesized and its surface was functionalized to attain amino-functionalized nanoparticles. Laccase enzyme was covalently immobilized onto ZIF-8 nanoparticles via glutaraldehyde (GA) as the linker to prepare a novel MOF-based nanobiocatalyst (NBC) for degrading organic pollutant (Acid Blue 92: AB92). The FTIR, FESEM, TEM, XRD, BET, and TGA were employed for characterizing of all prepared samples. The effect of catalyst mass, AB92 concentration, temperature, and pH were studied on dye decolorization of. The results showed that the biodegradation amount of AB92 followed by the Michaelis-Menten kinetic model.
The present paper investigates the surface modification of activated carbon (AC) by alkaline (NaOH) and dye removal ability of the surface modified activated carbon (SMAC). Acid Red 14 (AR14) and Acid Blue 92 (AB92) were used as the dye models. The surface characteristics of SMAC were investigated using the Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and surface area. The possible mechanism of the adsorption process and dye interaction with SMAC surface was analyzed. The effects of adsorbent dosage, initial dye concentration, and pH on the dye removal were investigated. The isotherm and kinetic of dye adsorption were studied. The adsorption isotherm of the dyes onto AC and SMAC followed Langmuir and Freundlich isotherms, respectively. The kinetic of dyes onto both AC and SMAC followed pseudo-second-order kinetic model. The results indicated that the alkaline (NaOH) treatment of AC was an efficient method to modify the AC. The maximum adsorption capacity (Q max) of AR14 and AB92 was 2.50 and 0.69 mg/g onto AC and 9.17 and 11.77 mg/g onto SMAC, respectively. Dye desorption tests (SMAC regeneration) showed that the maximum dye release of 85% for AR14 and 83% for AB92 was achieved in an aqueous solution at pH 12. In addition, the SMAC could be used as an eco-friendly adsorbent to remove the dyes from colored wastewater.
In this paper, copper oxide nanoparticle was synthesized and its surface was functionalized to remove dyes from single systems. The characteristics of the adsorbent were studied using Fourier transform infrared, X-ray diffraction, and scanning electron microscopy. Direct Red 31 (DR31) and Direct Red 80 (DR80) were used as model dyes. Least-squares support vector machine was used to predict dye removal. The model shows better performance in predicting dye removal compared to the kinetic models with average absolute percent relative error of 3.278 and 3.787% for DR31 and DR80, respectively, and correlation coefficients close to unity. Therefore, the used model could be reliable for prediction of the dye removal efficiency.
Poly(quaternary ammonium salt) (PQAS) as a cationic polymeric adsorbent was synthesized and characterized by FTIR. Isotherm, kinetic and thermodynamic of dye removal from single and binary systems was investigated. Acid Blue 25 (AB25) and Acid Red 18 (AR18) were used. The effect of operational parameters (adsorbent dose, pH, dye concentration and salt) on dye removal was studied. The dye removal followed the Langmuir isotherm and pseudo-first order kinetics. The adsorbent maximum dye adsorption capacity (Q 0) was 2000 and 1667mg/g for AB25 and AR18, respectively. The thermodynamic data showed that dye adsorption was spontaneous, endothermic, and a physisorption reaction.
Herein, metal-organic framework (MOF-199) as a nanoporous material was synthesized and characterized using FESEM, EDS, FTIR, XRD, BET and TGA. Basic Blue 41 was used for investigating the photocatalytic activity of MOF-199. The SEM image showed that a nanoporous MOF was synthesized. The effect of catalyst dosage, initial pollutant concentration and pH on decolorization was studied. Contaminant degradation increases by increasing catalyst dose and decreases by initial dye concentration. Decolorization rate decreases by decreasing the pH of solution due to the electrostatic repletion of the cationic dye from the surface of MOF-199. The UV–Vis spectra of dye solution during pollutant degradation by MOF-199 showed that the dye absorbance in visible region of spectrum diminished because of the azo band destruction. The data indicated that the synthesized nanoporous metal-organic framework-199 could be used as a photocatalyst for decolorizing wastewater.
