In this paper, the surface modification of silk fiber using anhydrides to graft the polysaccharide chitosan and dyeing ability of the grafted silk were studied. Silk fiber was degummed and acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), in different solvents (dimethyl sulfoxide (DMSO) and N,N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L:R) and reaction time on acylation of silk were studied. The polysaccharide chitosan was grafted to the acylated silk fiber and dyed by acid dye (Acid Black NB.B). The effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated silk were investigated. The physical properties show sensible changes regardless of weight gain. Scanning electron microscopy (SEM) analysis showed the presence of foreign materials firmly attached to the surface of silk. FTIR spectroscopy provided evidence that chitosan was grafted onto the acylated silk through the formation of new covalent bonds. The dyeing of the chitosan grafted-acylated silk fiber indicated the higher dye ability in comparison to the acylated and degummed silk samples. The mechanism of chitosan grafting over degummed silk through anhydride linkage was proposed. The findings of this research support the potential production of new environmentally friendly textile fibers. It is worthwhile to mention that the grafted samples have antibacterial potential due to the antibacterial property of chitosan molecules.
Herein, 1,4-benzenedicarboxylate (BDC) and 2-amino-1,4-benzenedicarboxylate (NH2-BDC) as organic linkers and tetraisopropyl orthotitanate as a metal source were used to synthesize several metal-organic frameworks (MOFs) nanomaterials. Five Materials Institut Lavoisiers (MILs) as MOFs include MIL-125(Ti), NH2-MIL-125(Ti) and three MILs with different organic linkers molar ratios (BDC/NH2-BDC: 75/25, 50/50 and 25/75 denoted as MIL-X1, MIL-X2 and MIL-X3, respectively). The synthesized nanomaterials were used for ultrasound-aided adsorption of cationic dyes (Basic Red 46 (BR46), Basic Blue 41 (BB41) and Methylene Blue (MB)) from single and multicomponent (binary) systems. The BET, XRD, FTIR, SEM, TEM, TGA and zeta potential were used for characterizing the MILs. Dye removal followed pseudo-second order kinetics with constant rate of 0.20833, 0.00481 and 0.00051 mg/g min for BR46, BB41 and MB, respectively. In addition dye adsorption obeyed the Langmuir isotherm model and the experimental dye adsorption capacity for BR46, BB41 and MB was 1296, 1257 and 862 mg/g, respectively. The synthesized MIL showed high reusability and stability over three cycles. The adsorption thermodynamics data presented that dye removal was a spontaneous, endothermic and physical reaction. The free Gibbs energy for dye removal by the NH2-MIL-125(Ti) at 308K was −19.424, −15.721 and −17.413 kJ/mol for BR46, BB41 and MB, respectively.
In this research, modified zinc ferrite nanoparticle by 3-amino propyl triethoxysilane was synthesized and its dye removal ability was studied. The synthesized adsorbent was characterized using Fourier Transform Infrared and Scanning Electron Microscopy. Acid bule 25 (AB25), Direct green 6 (DG6) and Direct red 23 (DR23), were used as model compounds. The effect of operational parameter such as adsorbent dosage, pH, dye concentration and salt was evaluated. The isotherm and kinetic of dye adsorption were studied. The maximum dye adsorption capacity (Q0) of adsorbent for AB25, DG6 and DR23 was 333 mg/g, 53 mg/g and 167 mg/g, respectively. It was found that dye adsorption onto adsorbent followed with Langmuir isotherm. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. The results showed that the modified zinc ferrite nanoparticle being a high dye adsorption capacity might be a suitable adsorbent.
The magnetic adsorbent nanoparticle was modified using cationic surface active agent. Zinc ferrite nanoparticle and cetyl trimethylammonium bromide were used as an adsorbent and a surface active agent, respectively. Dye removal ability of the surface modified nanoparticle as an adsorbent was investigated. Direct Green 6 (DG6), Direct Red 31 (DR31) and Direct Red 23 (DR23) were used. The characteristics of the adsorbent were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of adsorbent dosage, initial dye concentration and salt was evaluated. In ternary system, dye removal of the adsorbent at 90, 120, 150 and 200 mg/L dye concentration was 63, 45, 30 and 23% for DR23, 97, 90, 78 and 45% for DR31 and 51, 48, 42 and 37% for DG6, respectively. It was found that dye adsorption onto the adsorbent followed Langmuir isotherm. The adsorption kinetic of dyes was found to conform to pseudo-second order kinetics.
This paper investigates the mineralization and numerical finite element model for simulation of decolorization of Solophenyl Red 3BL (SR) by nanophotocatalysis using immobilized titania nanoparticle. A simple and effective method was developed for the immobilization of titania nanoparticles. UV–vis, ion chromatography (IC) and total organic carbon (TOC) analyses were employed to obtain the details of the photocatalytic decolorization and mineralization of SR. The nitrate and sulfate anions were detected as photocatalytic mineralization products of SR. Ninety-two percent total organic carbon can be eliminated after 240min of irradiation time.The SEEP/W model was incorporated into the CTRN/W model and modified to solve mathematical equation describing decolorization process. The numerical model was first calibrated with an analytical equation for a simple mass transport problem through groundwater flow system. The simulation results were then compared to those results obtained from an experimental test for the decolorization of SR by nanophotocatalysis process and close agreement was achieved.
No abstract is provided for this article.
In this paper, the surface of polyacrylonitrile (PAN) nanofiber was modified by polyamidoamine (PAMAM) and its dye removal ability was investigated.In this regard, PAN polymer was functionalized by diethylenetriamine (DETA), and the PAMAM dendrimer molecule was grafted to the surface of functionalized nanofiber by glutaraldehyde.The characterization of nanofibers showed that PAMAM molecules were attached to DETA through the formation of amine groups.Scanning electron microscope images of functionalized and surface grafted PAN nanofiber showed a rough surface and deposition of a dense layer on the nanofiber surface, respectively.Also, the surface average roughness of nanofibers increased from 42.4-46.4nm and 68.6-81.9nm for PAN-DETA and PAMAM grafted PAN-DETA compared to untreated PAN nanofiber, respectively.The result of the adsorption study showed that the adsorption process followed Langmuir isotherm and pseudo-second-order kinetic models.The dye removal conditions were optimized by the response surface methodology (RSM) model.The RSM result indicated that pH variable is more effective in dye adsorption.It was observed that the amounts of the dye adsorbed onto the prepared nanofiber were influenced by the initial pH, contact time, initial concentrations of the dye solutions, and ionic strength.The prepared nanofibers showed good regeneration ability and high adsorption capacities even after ten adsorption/desorption cycles.
We have studied the structural, electronical and optical properties of pure α-Al2O3(corundum) and doped with manganese by the first principles calculations method based on the density functional theory (DFT), with generalized gradient approximation (GGA). Obtained results show that α-Al2O3 has an energy gap of 6.3 eV and the substitution of manganese decreases the energy gap so that spin splitting effect is observed. Calculated optical results show that with adding this impurity, reflectivity increase at low energy and decreases at high energy; also static refractive index increases. Key words: Corundum, manganese, density functional theory (DFT), energy gap, refractive index.
Herein, a thin film nanocomposite (TFN) membrane was prepared through deposition of a very thin mixed matrix layer of PEBAX®1657/chitosan-wrapped multiwalled carbon nanotubes (CWNTs) on an ultraporous polyethersulfone (PES) substrate. The eco-friendly CWNTs were synthesized via non-covalent functionalization of MWNTs by carbohydrate polymer chitosan. They were then incorporated into PEBAX®1657 matrix at different loadings (0, 0.1, 0.5, 1 and 2 wt%). The membranes were analyzed using SEM, AFM, FTIR, XRD and contact angel analyses. Furthermore, pure water fluxes through the membranes were investigated at 1, 2 and 3 bar and Malachite green separation properties of the membranes were evaluated at 2 bar. The results showed that the highest permeate flux (∼13.85 L/m2h) and rejection (∼98.7%) were obtained at 1 wt% and 0.1 wt% CWNT dosages, respectively. Additionally, the slight flux decline of the membranes during 5 h indicated the improved antifouling properties.
This study presents the adsorption performance indicator for the evaluation of thermal power plant CO2 capture on mesoporous graphene oxide/TiO2 nanocomposite. To begin, this adsorbent was synthesized and characterized using N2 adsorption-desorption measurements (BET and BJH methods), X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM) and FT-IR spectroscopy. Subsequently, the pure single-component adsorption isotherms measured at 298 K and the Ideal Adsorbed Solution Theory (IAST) solved with direct search minimisation were applied to estimate the selectivity of the synthesized mesoporous graphene oxide/TiO2 nanocomposite for CO2 over N2 and predict CO2 adsorption capacity in the CO2:N2 binary gas mixtures, including the molar ratio of 5:95, 10:90 and 15:85. Finally, the results validated by the breakthrough experiments at a fixed-bed column were applied to estimate the Adsorption Performance Indicator (API) for the evaluation of CO2 separation from N2 in the Pressure Swing Adsorption (PSA) process with respect to different types of thermal power plants.
No abstract is provided for this article.
Excessive discharge of synthetic azo dyes into the aquatic ecosystem is a global concern. Here, we develop a green approach to remediate dye pollutants by fabricating an easily separable bio-nanocomposite, based on nanofibrils from whey protein concentrate together with montmorillonite. The nanocomposite was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and surface area analysis. Nanofibrils lead to a uniform dispersion of montmorillonite in the matrix and also reinforce the nanocomposite. The adsorption efficacy was monitored using cationic (Chrysoidine-G, Bismarck brown-R), reactive (reactive black-5, reactive orange-16), acidic (acid red-88, acid red-114) and direct (direct violet-51, Congo red) dyes. The nanocomposite adsorbed different dyes with different kinetics, cationic dyes quicker and reactive dyes slower. Greater than 93% of Chrysoidine-G was adsorbed over a wide range of dye concentration and pH. Acidic pH and higher temperature are more favorable for the process. Equilibrium adsorption data were reasonably fitted with a linear (Nernst) isotherm model indicating the existence of an unlimited number of adsorption sites which is consistent with the high experimental uptake of 731 mg/g. Kinetic data were well-described by pseudo-second-order and intra-particle diffusion models. We conclude that this environmentally friendly nanocomposite has good potential for use in wastewater treatment and related purposes.
In this paper, the effect of activated carbon (AC) on the photocatalytic degradation of dyes using photo-Fenton process was investigated. Reactive Red 198 (RR198) and Reactive Red 120 (RR120) were used as model dyes. The surface characteristics of AC were investigated using Fourier transform infrared. Photocatalytic dye degradation was studied using UV–Vis spectrophotometer and ion chromatography. The effects of AC dosage, initial dye concentration, pH, and salt on dye degradation were investigated. Formate, acetate, and oxalate anions were detected as dominant aliphatic intermediates, where they were further oxidized slowly to CO2. Nitrate, chloride, and sulfate anions were detected as the photocatalytic mineralization products of dyes. The results indicated that the AC/Fe could be used as an eco-friendly material to remove dyes. In addition, AC has synergistic effect when degrading dyes from colored wastewater using photo-Fenton process.
Herein, novel ZIF-67/CS/PVA (CNF-2) nanofiber composites using a two-step seed-assisted in situ electrospinning method, with cobalt-based zeolitic imidazolate framework (ZIF-67) as the precursor was prepared. SEM, EDX, AFM, FTIR, and XRD analyses revealed the optimal formation of ZIF-67 nanoparticles both inside and on the surface of CS/PVA nanofibers without compromising the structure of these electrospun nanofibers. The unique porous structure and heterointerfaces of the ZIF-67/CS/PVA (CNF-2) nanofiber composites demonstrated remarkable adsorption capacities for cadmium (Cd) and tetracycline hydrochloride (TCH), achieving 1137.94 and 1029.5 mg/g, respectively. The adsorption effectiveness for Cd and TCH was 94.83 % and 85.79 %, respectively, under optimal adsorption conditions: pH 8, adsorbent dosage of 0.01 g, initial Cd and TCH concentration of 80 mg/L, and a contact time of 120 min. The study of coexisting Cd and TCH adsorption on CNF-2 under varying pH conditions (4–8) reveals a significant enhancement in Cd adsorption efficiency, increasing from 41.91 % to 97.49 %. Conversely, TCH exhibits a more modest improvement, with its adsorption efficiency rising from 72.53 % to 85.96 %. Kinetic and equilibrium studies revealed that the adsorption followed pseudo-second-order kinetics and the Langmuir isotherm. The prepared nanofiber adsorbed 60 % of Malachite green dye. The engineered adsorbent demonstrated impressive regeneration potential, maintaining its efficiency over three successive adsorption–desorption cycles.
This study investigated the potential use of a low-cost inorganic powder (Persian Kaolin) for removal of Basic Yellow 28 (BY28), Methylene Blue (MB) and Malachite Green (MG) from aqueous solution. Kaolin was characterized via a laser particle size analyzer (PSA), scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. The effect of adsorbent dosage, dye concentration, initial pH and the presence of various electrolytes was studied. The isotherm data of dyes were correlated reasonably well by the Langmuir adsorption isotherm. The values of the adsorption capacity of kaolin towards the cationic dyes ranged from 16mg/g to 52mg/g, being probably dependent on the geometry of the dye molecules. The resulting degrees of dye removal were 65–99% for initial dye concentration of 10mg/L and for kaolin loadings of 0.8–2.5g/L. It was found that the adsorption of dyes on kaolin followed a pseudo-second order equation. The recovery and reuse of kaolin for a second and third time have also been studied. The thermodynamic studies showed that the dye adsorption onto kaolin is a spontaneous, endothermic and a physical reaction.
Herein, Fe3O4 nanoparticle was first synthesized, then its surface was modified with tetraethyl orthosilicate, and finally, metronidazole was covalently fixed on its surface to synthesize Fe3O4@SiO2@(CH2)3-Metronidazole (FSCM). Synthesized materials were characterized. The catalytic activity of MNPs Fe3O4@SiO2@(CH2)3-metronidazole was studied by the aromatic bromination/iodination of aromatics under solvent-free conditions. Bromination/iodination products were characterized using 1H NMR and 13C NMR. The conversion yield of aniline to 4-bromoaniline using 0, 100, 200, 300, 400, and 500 mg of Fe3O4@SiO2@(CH2)3-Metronidazole at 25 min and 25 °C were trace, 76, 85, 96, 89, and 79 %, respectively. The catalyst showed high catalytic performance with excellent yields at short reaction times. The results showed that Fe3O4@SiO2@(CH2)3-Metronidazole can be used as a heterogeneous catalyst after 5 cycles without significant loss of catalytic activity (89%) for the bromination and iodination of aromatic hydrocarbons with KBr/KI.
The presence of tetracycline and dye as organic contaminants has led to the poisoning of wastewater. The aim of this study is to synthesize a novel biocomposite material by decorating natural starch polymer granules with metal-organic framework (MIL100) and cobalt ferrite magnetic (CoFe2O4) nanoparticles. The synthesized ternary magnetic biocomposite (Starch/MIL100/CoFe2O4) was used for the photocatalytic degradation of methylene blue (MB) and tetracycline (TCN) using LED visible light. The synthesis of the biocomposite was confirmed through comprehensive analyses (XRD, SEM, FTIR, BET, EDX, MAP, DRS, pHzpc, TGA, and Raman). The evaluation examined the influence of initial pollutant concentration, catalyst dosage, pH, and the impact of anions on pollutant removal. The results show that the pollutant degradation ability of biocomposite has been significantly improved, so that the base biopolymer, starch, achieved 18% tetracycline degradation, but when decorated with MIL100 and cobalt ferrite, it increased to 91.2%. It was observed that the degradation for methylene blue improved from 12% for starch to 96.6% for the magnetic biocomposite. The tetracycline degradation decreased by more than 20% in the presence of NaCl, NaNO3, and Na2SO4. The finding shows that the biocomposite adheres to first-order kinetics for both pollutants. The scavengers test identified hydroxyl radicals as the most effective active species in the degradation process. High stability, even after passing 5 cycles of recycling was observed for the biocomposite. The results indicated that the facile and green synthesized Starch/MIL100/CoFe2O4 magnetic biocomposite could be used as an effective photocatalyst for the degradation of Tetracycline and dye at room temperature.
