Green synthesis of MOF-on-MOF is an effective method to prepare the environmentally friendly photocatalyst using metal–organic frameworks (MOFs). Herein, ZIF-8 was synthesized on MIL-100 (Fe) (ZM composites) with different weight percent ratios of ZIF-8 and denoted as ZM21, ZM11 and ZM12. They were investigated as environmentally friendly photocatalysts for the degradation of Methylene Blue (MB) using visible light. XRD, FT-IR, SEM, EDX, and DRS were used to characterize the synthesized materials (ZIF-8, MIL-100, ZM21, ZM11, and ZM12). The ZM11 composite had the highest dye degradation ability. The MB photocatalytic degradation for the ZIF-8, MIL-100, ZM21, ZM11, and ZM12 were 12.59%, 31.27%, 29.45%, 86.3, and 31.51%, respectively. MB degradation by ZM11 composite followed the first-order kinetic model. The effective radical for the MB photocatalytic degradation was the superoxide radical (•O2 –). The ZM11 composite had the ability of 76% dye removal from water after 3 cycles of MB degradation.
This research tried to perform a comprehensive evaluation of dye (Reactive Red 120 (RR120)) removal by the surfactant-modified montmorillonite (Mt). For this purpose, the experiments were carried on at two levels. In the first level, the adsorption behavior of cetylpyridinium chloride monohydrate (CPCM) and alkyl dimethyl benzyl ammonium chloride (ADBAC) onto Mt was assessed by electrical conductivity technique. In this manner, the critical micelle concentration (CMC) point of ADBAC and CPCM were achieved 0.41 g/L and 2.02 g/L, respectively. Next, modified Mt, as efficient adsorbent, was utilized to toxic anionic dye adsorption from model wastewater. The attraction force between the positive surface charge of modified Mt and the negative charge of RR120 dye molecules leads to the high adsorption capacity. The mostly-known adsorption isotherm models were applied to the experimental data. The obtained data of surfactants adsorption onto Mt, as well as the adsorption data related to RR120 dye removal using modified Mt, were well fitted with the Langmuir isotherm model. The maximum Langmuir capacity for CPCM and ADBAC adsorption by Mt was achieved 183.0 mg/g and 311.8 mg/g, respectively. This amount was found 227.3 mg/g and 243.09 mg/g regarding RR120 adsorption by ADBAC and CPCM-modified Mt, respectively. Also, the hydration inhibitive ability of surfactants was investigated, and the characteristic of them was examined through extensive inhibition evaluation experiments, including settlement, zeta potential, XRD, FTIR, particle size, and SEM analyses.
Herein, MIL-101 (Fe)/phosphotungstic acid (PA) composites were synthesized and characterized. Materials Institute Lavoisier (MIL-101 (Fe)) composites as metal-organic frameworks (MOFs) with 0, 0.347, 0.694 and 1.042 mmol of PA were synthesized and denoted as MIL, MP-1, MP-2, and MP-3, respectively. The synthesized MOFs were used to remove organic contaminants from binary systems (BB:Basic Blue 41 and MB:Methylene Blue). The synthesized materials were characterized in detail. Pollutant removal obeyed the Langmuir isotherm and pseudo-second-order kinetic. The free energy of adsorption for MP-2 at 298, 308, 318 and 328 K was −15.24,-15.93, −16.63 and −17.32 kJ/mol for BB and −15.04, −15.02, −15.01 and −14.99 kJ/mol for MB, respectively. Adsorption by the synthesized materials was spontaneous and endothermic process. The multicomponent dye removal data indicated that the synthesized MIL-101 (Fe)/phosphotungstic acid (PA) composites could be used as efficient adsorbents for treating colored wastewater. In addition, the synthesized MOFs were recyclable and regenerable adsorbents.
No abstract is provided for this article.
Reduced graphite oxide (rGO)-based materials have demonstrated promising potential for advanced oxidation processes. Along with its distinctive 2D characteristics, rGO offers the prospect of catalytic degradation of various kinds of organic pollutants from aqueous environments. The practical application of rGO as a metal-free catalyst material to promote the Fenton reaction depends on the degree of rGO reduction. In this regard, the rGO was prepared according to oxidation by modified Hummers' method and two-step reduction via hydrothermal and calcination in the N2 atmosphere. The as-prepared rGO was characterized in terms of X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, UV-vis absorption spectroscopy, and transmission electron microscopy. The effectiveness of as-prepared rGO as a photocatalyst and the metal-free catalyst to decolorize different textile dyes, including basic red 46, basic red 18, and methylene blue, was investigated in visible/rGO and visible/rGO/H2O2 systems. The impact of operational factors such as catalyst dose, pH, and initial dye concentration was examined. The dye degradation process was investigated by the pseudo-first-order kinetic model. In addition, the recyclability of rGO in the visible/rGO/H2O2 system was examined.
In this paper, the corrosion inhibition of cationic gemini surfactant, in the absence and presence of halide salts (NaCl, NaBr and NaI) on steel in HCl was investigated at 20±1°C. The effects of pH, immersion time and salt concentration on the corrosion inhibition of steel were studied using weight loss, open circuit potential and electrochemical impedance spectroscopy. Inhibition efficiency increases by increasing surfactant concentration. Synergistic effect between surfactant and salts was studied. The inhibition efficiency increases by increasing salt concentration. This composite inhibitor containing gemini surfactant and halide was efficient and low-cost for steel corrosion inhibition in HCl.
Laccase was immobilized onto manganese ferrite nanoparticle (MFN) and dye decolorization from single and binary systems was studied. The characteristics of laccase immobilized manganese ferrite nanoparticle (LIMFN) were investigated using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Direct red 31 (DR31), Acid blue 92 (AB92) and Direct green 6 (DG6) were used. A least square support vector machine (LSSVM) was developed to predict the decolorization efficiency of various single and binary systems based on the obtained laboratory data under different experimental conditions. Statistical and graphical quality measures were also employed to evaluate the performance and accuracy of the developed intelligent models. It is shown that the predictions of the designed LSSVM models are in close agreement with the experimental data. The effects of LIMFN dosage, pH and dye concentration on dye decolorization from single and binary systems were evaluated. Decolorization kinetics followed Michaelis–Menten Model.
In this paper, the preparation, characterization and dye adsorption properties of novel biocompatible composite (Sodium Alginate/titania nanoparticle) (SA/n-TiO2) were investigated. Titania nanoparticles were immobilized onto Sodium Alginate. Physical characteristics of SA/n-TiO2 were studied using Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and wavelength dispersive X-ray spectroscopy (WDX). Two textile dyes, Direct Red 80 (DR80) and Acid Green 25 (AG25), were used as model compounds. The effect of operational parameter such as SA/n-TiO2 dosage, initial dye concentration and pH was evaluated at 25°C. The isotherm, kinetic and thermodynamic of dye adsorption were studied. The data were evaluated for compliance with the different isotherm models. It was found that DR80 and AG25 followed with Langmuir isotherm. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. The thermodynamic data showed that adsorption process was spontaneous, endothermic and physisorption reaction. Based on the data of present investigation, one could conclude that the SA/n-TiO2 being a biocompatible, eco-friendly and low-cost adsorbent might be a suitable alternative for elimination of dyes from colored aqueous solutions.
In this paper, the preparation, characterization and dye adsorption properties of soy meal hull activated carbon (SMH-AC) were investigated. Physical characteristics of SMH-AC were studied using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Two textile dyes, Acid Red 14 (AR14) and Acid Red 18 (AR18), were used as model compounds. The effects of operational parameter such as SMH-AC dosage, initial dye concentration, pH and salt on dye removal were evaluated. The isotherm of dye adsorption was studied. The data were evaluated for compliance with the Langmuir and Freundlich isotherm models. It was found that AR14 and AR18 followed with Langmuir isotherm. Based on the data of present investigation, one could conclude that the SMH-AC being an eco-friendly and low-cost adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions.
No abstract is provided for this article.
In this paper, cadmium selenide quantum dot (CdSe QD)-zinc oxide (ZnO) nanocomposite (CdSe QD-ZnO) was synthesized and characterized and its photocatalytic dye degradation ability was investigated. The XRD, FTIR, UV–Vis, AFM and SEM were used to characterize the synthesized nanomaterials. The correlation coefficient of pseudo-first-order kinetic reaction is 0.98. The rate constants from 20 to 30 mg/L of pollutant concentrations was reduced by the order of 0.9. The temporal change in dye concentration reduces as the photocatalyst dosage increase up to optimum value of 0.04 g/L, then beyond that value the increase in the dosage becomes detrimental. Antibacterial activity of the synthesized nanocomposite as a safe photocatalyst was studied in details. Antibacterial activity of as prepared samples was also examined against Escherichia coli (E. coli). For in vitro study, Human umbilical vein endothelial cells (HUVEC) was utilized for the modeling of toxicity of each as prepared samples as representative of human normal cell line. In vivo study was conducted using leeches (Hirudo orientalis). In the presence of ethanol as hydroxyl radical (OH) scavenger, the removal efficiency significantly depresses compared to the di methyl sulfoxide as electron scavengers suggesting OH possesses a major role in photocatalytic dye (Basic Red 18: BR18) decolorization. By coupling with CdSe QD, the zone of inhibition was greatly increased suggesting the size dependent inactivation of E. coli. The results presented that the composite had no significant effect on the proliferation of HUVEC normal cells. In addition, the treatment of cells with ZnO and the composite does not impact on the cell morphology.
In this paper, CuO–NiO nanocomposite was synthesized and used to remove cationic dyes from wastewater. The scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were used to characterize the nanocomposite. Basic Red 18 (BR18) and Basic Blue 41 (BB41) were used as cationic dyes. Artificial neural network (ANN) model was used to predict the efficiency of dye removal. The effect of adsorbent dosage and dye concentration on dye removal was evaluated. The studied operating variables were used as the input to the constructed neural network to predict the dye removal at any time as the output or the target. The backpropagation neural network with Levenberg–Marquardt training algorithm was used to predict adsorption efficiency with a tangent sigmoid transfer function (tansig) at hidden layer and a linear transfer function (purelin) at output layer. The results showed the dye adsorption kinetics followed pseudo-second-order kinetics model. Dye removal isotherm was fitted with Temkin and Freundlich models for BB41 and BR18, respectively. The linear regression between the network outputs and the corresponding targets were proven to be satisfactory with a correlation coefficient. In addition, ANN modeling could effectively predict and simulate the behavior of the process.
Nanofibers and metal-organic frameworks (MOFs) have been widely used in water and wastewater treatment. In the present work, α–Fe2O3 nanofiber was synthesized and developed by the synthesis of zeolitic imidazolate framework-8 (ZIF-8) on it. The α–Fe2O3 nanofiber was successfully fabricated by one-step electrospinning of PVA followed by a hydrothermal reaction on PVA nanofiber and calcination of the electrospun PVA-Fe3O4 fiber. ZIF-8/Fe2O3 composite nanofibers (ZFCN) with different amounts of Fe2O3 nanofiber (5, 10 and 20% wt denoted as ZFCN-5, ZFCN-10 and ZFCN-20) were made by green method at room temperature and atmospheric pressure and characterized using SEM, AFM, Zeta potential, FTIR, and XRD. The photocatalytic activity of these composites was investigated for degrading Reactive Red 198 (RR198). According to the results, ZFCN-20 showed the highest dye decolorization (94%). The kinetics of RR198 degradation was zero-order for both ZIF-8 and Fe2O3 nanofiber and first-order for decolorization by ZIF-8/Fe2O3 composite nanofiber.
