جستجوی مقالات مرتبط با کلیدواژه « dye » در نشریات گروه « علوم پایه »

With the ex-potentially increase pollutants of dyes, the purification of cationic dye waste water has been an urgent environmental problem. As a new kind of porous adsorbent, hydrogel modified activated carbon frameworks still face challenges in agglomeration, regeneration, reuse ability, and synthesis environmentally un-friendly. In this work, activated carbon was grown in situ on the surface of sodium alginate (AAc-AM) beads to fabricate (AAc-co-AM)/AC. This study works to examine the elimination of Brilliant Blue (BB), a harmful and persistent dye that could cause extensive ecological damage, from an aqueous solution via adjusting the amount of acrylamide (AM) and the degree of co-polymer cross-linking. The co-polymer of hydrogels efficiently removes BB in a brief time frame. The synthesized hydrogel was characterized via FESEM and TEM. The best adsorption efficiency of the nanocomposite was 114.4 mg.g-1. Reactivation appears to indicate that the material could be utilized repeatedly and has a better ability to resist interference. In addition, the percentage removal of BB dye by hydrogel from aqueous solution were above 91.40%. Therefore, the hydrogel appears great potential for the wastewater.

The research presents the synthesis and fabrication of dye-sensitized solar cells (DSSCs) on the influence of sodium arsenic on the enhancement of TiO2/dye as photosensitizers, where Hibiscus sabdariffa (roselle) and Vernonia amygdalina (bitter leaf) were used as a source of the chlorophyll, sodium arsenic (NaAs) material of different concentration (0.1-0.4 mol), was synthesized as a layer on top of TiO2. The surface morphology study of TiO2/NaAs0.1, TiO2/NaAs0.2/ bitter leaf dye, TiO2/NaAs0.3/ roselle dye, and TiO2/NaAs0.4/the mixture of bitter leaf dye and roselle dye revealed that the micrograph is usually defined with the granular shape of nanotubes. The grain size of TiO2/NaAs0.1 is not too large and delineated by an immense sum of aggregated nanoparticles. The cells structure is polycrystalline with a most outstanding peak at 2 theta angles of 26.73° and 51.84o corresponding to hkl index numbers (111) and (202). The films have a very high absorbance from the plot, and the absorbance of the films increases as the dye molecules vary. The high absorbance of the films shows that the DSSCs will be a good material for photovoltaic applications. The fill factor of the films is 0.54, 1.24, 1.23, and 0.99 respectively while the conversion efficiency of 0.86%, 4.48%, 3.44%, and 1.81% was recorded.

The kinetics of catalytic degradation of methyl violet using biosynthesized silver   nanoparticles was studied spectrophotometrically. The biosynthesis process synthesized the silver nanoparticles using Azadirachta indica leaves extract and characterized by spectral techniques. Uv spectra showed the reduction of silver nitrate into silver nanoparticles. Atomic force microscopy analysis showed the configuration, morphology, and size of silver nanoparticles. It was observed silver nanoparticles are spherical and produced in high percentages. The kinetics of degradation of methyl violet with silver nanoparticles was analyzed by observing the change in absorbance with respect to time at 583nm as a function of pH, concentration of nanoparticle, catalyst, and temperature. The reaction follows pseudo-first-order kinetics depends on the concentration of nanoparticles and is independent of the concentration of methyl violet. The degradation process was found to be more favorable at low temperatures and in the basic medium at pH 11 The activation parameters are also evaluated.

Phenols have attracted global interest in the sphere of environmental management due to their potential toxicity on human health. This study determined concentrations of three priority phenolic compounds in effluent and water of a local textile industry in Abeokuta, Nigeria.  During tie-dye production, triplicates of effluent, well water, stream and control water were collected three times from five points to give a total of forty-five samples. Physicochemical parameters of samples including temperature, pH, electrical conductivity (EC), total suspended solids (TSS) and total dissolved solids (TDS) were determined according to standard methods while the concentrations of the priority phenolic compounds (4-nitrophenol, 4-chloro-3-methylphenol and 2, 4-dinitrophenol) were determined using High Performance Liquid Chromatography equipped with Ultra-Violet detector (HPLC/UV). Data obtained were subjected to descriptive (mean and standard deviation) and inferential (ANOVA) statistics. pH, EC and TSS of effluent and water samples were higher than the permissible limits of World Health Organization (WHO) and Federal Environmental Protection Agency (FEPA) while temperature of the effluent samples and TDS of the well water samples were within standard values. Higher concentrations of the priority phenolic compounds occurred in effluent than water samples but 4-nitrophenol was below detection limit (DL) in water samples. Concentrations of 4-nitrophenol, 4-chloro-3-methylphenol and 2,4-dinitrophenol in effluent exceeded stipulated standard of WHO (0.01 mg/L) and water samples. High concentrations of phenols in water bodies at the local textile industry suggest uncontrolled discharge of effluent from the industry which could eventually reach surface and ground water with potential significant health implications to the populace.

In this study, a microwave assisted hydrothermal technique was employed for the synthesis of CNT/ZnO nanocomposite. Carbon nanotubes were obtained from incineration stacks in furnaces. They were treated with concentrated (0.1 N) H3PO4. The structures of nano-composites were characterized via utilizing powder (FE-SEM), and (TEM). Specific surface area (BET), total pore volume, and mean pore size were too studied through utilizing Bruneuer Emmatt Teller (BET) technique to refer to the properties surface of the nano-composites. Several operational factors like initial concentration of GRL dye, amount of CNT/ZnO nanocomposite, solution of pH, and temperature solution by utilize of CNT/ZnO nanocomposite in the adsorption of GRL dye. It was found that removal percentage E % rises with increase weight of the nanocomposite until all the active sites of the nanocomposite are saturated. The percentage removal of GRL dye rises from 45.42% to 90.853% for solution pH increase about 3.2-10.5. The result of the kinetic was studied by means of several model kinetic like first model, the second  model,  and Elcovich model was found to be the maximum kinetic model second-order (R2=0.9986) for our adsorption investigation. The thermodynamic factor having change Gibbs energy (ΔG), change entropy (ΔS), and change enthalpy (ΔH). The negative value of ∆H (-9.043 kJ.mol-1) was estimated for the adsorption method and the adsorption is a physical and exothermic, positive value ∆S (13.8469 J.mol-1 K-1), and the values negative of (∆G) in the range temperature of 10-30 oC, confirming that the dye adsorption on to Nano composite was spontaneous.

The excitation wavelength (λex= 490 nm) at room temperature was determined to examine the impact of pH on the absorption and emission spectra of an eosin y compound dissolved in ethanol at a concentration of 1×10-5 M. The relative fluorescence intensity of eosin in ethanol at the concentration of 1×10-5 M was decreasing with the increasing of acidity (pH < 7) and the red shift of fluorescence was decreasing by adding a few drops of 1N solution of HCl, (pH normal = 7.26). However when a few droplets of NaOH were added, it was observed that the opposite, the relative fluorescence intensity was increasing with increasing basicity (pH > 7) and the red shift of fluorescence was decreasing with increasing basicity. Characteristics like fluorescence and absorption wavelength were further measured, along with graphical correlations like the one between pH and the relative fluorescence intensity. The relative fluorescence intensity of eosin in ethanol at the concentration of 1×10-5 M was decreasing with increasing acidity and the red shift of fluorescence was decreasing with increasing acidity (pH 7). However when a few droplets of NaOH were added, it was observed that the opposite was true: the relative fluorescence intensity was increasing with increasing basicity and the red shift of fluorescence was decreasing with increasing basicity.

Water contamination by various pollutants, such as conventional pollutants like dyes and other emerging micropollutants, is of great concern. Nowadays, there are a host of processes for the removal of dyes from contaminated water. Due to its greater surface area, mechanical properties, and thermal properties, PANI got wide acceptance. It is prepared by chemical, electrochemical, or photochemical polymerizations. Smart properties of PANI are further enhanced by adding dopants which may be inorganic or organic, like HCl, H2SO4, and nicotinic acid. Due to π conjugated electrons, PANI nanocomposites photo-catalytically degrade dye components from wastewater. However, adsorption is the most efficient and promising one. These composites become good hosts to adsorb dye components on their surface by cationic π-interaction or anionic π- interaction. The unique doping and dedoping properties of PANI change its morphology, pore size, and surface charge, enhancing the adsorbate-adsorbent interactions and the adsorption performance. The adsorption mechanism of dye on the surface of the PANI nanocomposite involves H-bonding, van der Walls interactions, covalent interactions, and electrostatic interactions. In the end, future perspectives on removing dyes using PANI are discussed.

In the present work, dye-sensitized solar cells (DSSCs) were fabricated by using natural dye extracted from eight different flowers namely: [(MN1) Turkish Hibiscus sabdariffa, (MN2) Iraqi Hibiscus sabdariffa, (MN3) Rosehips, (MN4) Lavandula, (MN5) Nerium oleander, (MN6) Red Bougainvillea, (MN7) Pomegranate flower, and (MN8) Pink Bougainvillea] extracts as a photosensitizer. The UV-Vis absorption spectra for all eight samples were recorded at room temperature by using a mixture of 0.1 mol.L−1 HCl and ethanol, and also in different solvents. In addition, the effect of the pH value of these dyes on absorbance were investigated. Moreover, the Fourier transform infrared (FT-IR) spectra of all dyes were recorded. The lamp power used to evaluate the DSSCs performance is 1000 W/m2. The power conversion efficiency (η) of extracted dyes was reached as follows: (MN1) =1.589 %, (MN2) =1.229 %, (MN3) =0.602 %, (MN4) = 0.927 %, (MN5) =0.684 %, (MN6) =1.317 %, (MN7) =1.059 %, and (MN8) =1.149 %.

NaY zeolite was impregnated by TiO2 to prepare a novel catalyst for the adsorption and photocatalytic degradation of methylene blue (MB). The samples were characterized by XRD, SEM, EDS, and FT-IR techniques. The percentage adsorption of MB on NaY reaches 88% and an adsorption capacity of 6.55 mg/g under optimized parameters ([MB] = 10 mg/L, pH = 6, S/L = 2 mg/L, and T = 25°C). The MB adsorption process follows Langmuir isotherm. The thermodynamic parameters were investigated and showed an endothermic and physical process. The MB adsorption also follows a pseudo-second-order kinetic. The photo-degradation of the MB dye was successfully carried out on the TiO2/NaY catalyst under sunlight. The MB photo-degradation also follows a Langmuir-Hinshelwood first-order kinetic.

Methyl orange (MO) is a common anionic azo dye that is a serious harmful pollutant to the environmental aquatic systems, so it must be treated before it can be discharged. Photocatalysts are usually semiconducting solid oxides that create an electron-hole pair by absorbing photons. These electron holes can react with molecules on the surface of the particles. Photocatalysts are used in water purification, self-cleaning glasses, the decomposition of organic molecules, etc. Photocatalysts are environmental cleaning materials that remove pollution from surfaces and can destroy organic compounds when exposed to sunlight or fluorescence. The photocatalytic process follows the following principles. Bentonite mineral is a natural adsorbent material that has good adsorption capacity. In this work, zinc oxide nanoparticles doped with cerium were prepared by the sol-gel method (SGM) and deposited on bentonite clay to degrade methyl orange (MO) dye. Important parameters that affected degradation efficiency such as contact time, amount of nanocatalyst, and initial dye concentration were investigated and optimized. Results showed that 100% degradation efficiency was obtained at 60 mg of nanocatalyst and 50 mg L-1 of methyl orange in 120 minutes. The Kinetics of the degradation process was consistent with pseudo-second-order and the adsorption isotherm of MO dye on nanocatalyst was fitted with the Langmuir isotherm model. The reusability of the synthesized nanocatalyst showed that the nanocatalyst was applied successfully seven times without a significant change in degradation efficiency.

Nanoparticles materials with good structural properties can serve as an excellent candidate for the remediation of wastewater. In this study, mesoporous gamma-alumina was synthesized from kaolin using polyoxyethylene (40) stearate (PS) surfactant. The XRD diffractogram of the alumina revealed broad peaks that signifies small crystallites, while the FTIR spectrum indicates that the alumina possessed both tetrahedral and octahedral structure. The surface area, average pore diameter, and pore volume obtained from the N2-sorption study are respectively 76.0 m2/g, 4.4 nm, and 0.14 cm3/g. The XRF result revealed up to 98% Al2O3 composition, indicating a very high purity of the alumina. The alumina (Nano-Al) was applied for the adsorption of Eriochrome Black T dye, and the process optimized using RSM analysis by Box-Behnken Design (BBD) model. From the optimization results, the model's R2 (0.8736) value implies 87.36% on the percent dye removal could be due to the variation in the independent variable. While the F-value of 7.68 implies the model is significant. Consequently, 98.2% dye removal was achieved under the optimum conditions. This may be attributed to the enhanced structural properties of the Nano-Al. The experimental data were fitted to Langmuir isotherm, and the adsorption kinetics data were fitted to pseudo-second-order model.

Adsorption capacity of nano metal oxide synthesized from waste hen egg shell for the removal of methylene blue dye from aqueous solution was investigated using batch and density function theory (DFT) process. The prepared egg shell nano particle (PESNP) were characterized using done using proximate X-ray fluorescence, Scanning electron microscopy, (SEM) and Thermogravimetric analysis. The results obtained indicated that PESNP is a good adsorbent for methylene blue. Their adsorption capacity was found to be influenced by initial dye concentration, adsorbent dose, pH, temperature and by the period of contact. The adsorption of the dye onto PESNG was found to be physical, spontaneous and best described by Freundlich and Temkin adsorption models. Adsorption kinetic study indicated that a pseudo second order kinetics is favoured. Result from the quantum chemical study indicated that the adsorption of methylene blue onto PESNP will preferentially occur through the sulphonium sulphur, nitrogen and benzene ring.

In this study, the adsorptive removal of two dyes (crystal violet (CV) and methylene blue (MB)) with HNO3 pre-treated water hyacinth powder (WHP) adsorbent was analysed. The experiments were designed using response surface methodology (RSM) with variable input parameter pH (2-12), adsorbent dose (0.5-3 g/L), initial dyes concentration (25-200 mg/L) and time (10-180 min). The optimization condition for dye removal were (pH = 7.22, adsorbent dose = 3.0 g/L, initial dye concentration = 195.28 mg/L and time of contact = 99.29 min) for CV with removal of 98.20% and (pH = 9.82, adsorbent dose = 2.96 g/L, initial dye concentration = 199.36 mg/L and contact time = 111.74 min) for MB with removal of 97.843%. The above findings observed that pre-treated water hyacinth powder can be utilised as a cost-effective and efficient adsorbent for dye effluent wastewater treatment.

We reported that the ultrasonically synthesized nanocrystalline cellulose (NCC) from microcrystalline cellulose has the capacity for use as natural and green matrices for the synthesis of silver nanoparticles. Cationic surfactant cetyltrimethylammonium bromide (CTAB) was employed as a modifier and stabilizer for NCC. The structure of as-synthesized composite (Ag/CTAB/NCC) was characterized by Fourier transform infrared spectroscopy (FT-IR); field emission scanning electron microscopy (FE-SEM); Transmission electron microscopy (TEM); Energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The XRD pattern confirmed the single cubic phase of Ag nanoparticles with a crystallite size of about 30 nm. The catalytic activity of Ag/CTAB/NCC has been analyzed by performing the reduction of certain toxic azo methyl orange dye (MO) (by two methods) and aromatic nitro compound of 4- nitrophenol (4-NP) in shorter time. The reduction of MO to hydrazine derivatives and 4-NP to 4-aminophenol takes place with pseudo-first-order rate constants. The reduction time regularly decreased and the rate of reduction (k) increases (3 fold) with increasing catalyst amount in method (2) (mmol NaBH4/mmol MO = 250 and 42 mg catalyst) compared to the method (1) (mmol NaBH4/mmol MO = 400 and 5 mg catalyst). The results indicated that spherical AgNPs immobilized CTAB-adsorbed NCC showed better catalytic activity and shorter reduction time towards the removal of methyl orange (k = 14.2 × 10-3 s-1, t =150 s) and 4-nitrophenol (k = 5.4 × 10-3 s-1, t = 180 s) compared with previous works that could be introduced as an effective method for the catalytic treatment of wastewater.

Water chemical pollution originates from a wide range of toxic derivatives, especially heavy metals and dyes. Its destructive effects on humans and the ecosystem have been considered as a serious environmental disaster. Therefore, there is a need to develop technologies to remove toxic pollutants from the environment. Adsorption is one of the most common methods of removing contaminants from wastewater among all the proposed methods. Adsorption is an optional method for industrial sewage treatment and a useful instrument for environmental protection. In recent years, numerous studies have been conducted to achieve low-cost, efficient, and environmentally friendly adsorbents. Among the low-cost adsorbents, the application of agricultural waste, as bio-adsorbent, is the most widely used for removing heavy metals and dyes. The advantages of using these compounds are low cost, good efficiency, minimal energy, simple maintenance and high adsorption capacity. This study deals with the risks, effects, and resources of manufacturers of heavy metal and dyes in addition to examination of agricultural wastes as low-cost adsorbents. Moreover, equilibrium, kinetic, and thermodynamic behaviors of the process of adsorption of heavy metal ions and dyes, using Langmuir and Freundlich adsorption isotherms, and Pseudo first and second-order kinetic models, and thermodynamic parameters were studied.

Cationic dye Acridine orange (AO) has wide applications especially in biologicalfields such as analysis of lysosomal and mitochondria content by flow cytometryand so on. In the current work, spectroscopy of acridine orange (AO) dye at bothlow concentrations (mdye/mwater=6.25×10-5, 3.12×10-5) and high concentrations(mdye/mwater=0.002, 0.001) was studied in confined water nanodroplets withinwater/AOT/n-hexane microemulsions (MEs) at a constant water content (W=[Water]/[AOT]=10) and as a function of mass fraction of droplet (MFD) usingabsorption and fluorescence spectroscopic techniques. The absorption spectraof the dye at high concentrations of Acridine orange (AO) dye molecules showedthat the absorption spectra of the samples deviated from Beer’s law, and arebroadened at larger MFD due to the interactions of AO dye molecules. Thefluorescence spectrum investigated at two higher concentrations (0.002, 0.001)and low concentrations (6.25×10-5, 3.12×10-5). At high concentration of the dye,quenching of fluorescence intensity observed due to the accumulation of the dyemolecules, coupled with a red shift with increasing MFD. However, in the lowerconcentration regime, enhancement of fluorescence intensity was observed withincreasing MFD. The Stokes’ shift of the dye for both high and low concentrationsincreased with MFD, but largely at high concentrations compared to that at lowconcentrations.