جستجوی مقالات مرتبط با کلیدواژه « dye » در نشریات گروه « محیط زیست »

In this study, the adsorption of methylene blue (MB) from an aqueous solution on copper-alginate (Cu(II)-A) granules containing activated carbon derived from polyethylene terephthalate (PEtAC) with different experimental conditions was investigated. The composition and structure of the granules were characterized by SEM and BET methods. The effect of various variables including dye concentration, pH, adsorbent amount, and contact time was investigated by batch method. Equilibrium data were evaluated using Langmuir, Freundlich, and Temkin isotherms. The adsorption isotherm fits well with the Langmuir model (0.9973), which shows that the MB dye adsorption on the granules is homogeneous. The maximum adsorption capacity under optimal conditions for the removal of MB was 86.96 mg/g. Kinetic data were analyzed using the first-order and second-order Lagergren equations. The quasi-second-order model showed the best fit for the synthetic studies (R2 = 0.9997). In addition, no obvious decrease was observed after up to five adsorption cycles, indicating that the PETAC/Cu (II) -A adsorbent has good stability and reusability. Overall, the results show that the prepared granules can be used an am efficient adsorbent for the treatment of colored effluents.

Advanced oxidation processes (AOPs) are recognized as the most effective and capable available methods to remove and degrade different kind of dyes. Among various advanced oxidation processes, Fenton process is one of the most effective techniques that are used successfully to remove dyes without producing additional toxic by-products.

In the present study, all experiments were performed in a 500 mL rectangular plexiglass cubic reactor. The effect of different system parameters including pH, [Fe2+] to [H2O2] ratio, initial dye concentration, H2O2 concentration, stirrer velocity and temperature were examined and optimized using one- factor- at- a- time (OFAT) method.

The results obtained from this study showed that Fenton process can remove 96 percent of Acid Blue 25 from aqueous solution. The optimal condition using Fenton process included initial concentration of 150 mg/l, pH= 3, molar ratio of [Fe2+]/[H2O2] = 0.3, stir. vel.= 100 rpm, temperature 43°C and 10 min contact time.

Fenton process is suggested as a suitable method for the removal of Acid Blue 25.

Conversion of agricultural wastes to valuable products is one of the sustainable method to prevent air pollution thet arises from biomass open burning. One of these new and valuable products are lignocellulosic aerogels, which due to their superior characteristics, such porous structure and large surface area can be used for removal of various pollutants such as dye. In this study, lignocellulosic aerogel obtained from rice straw were used to remove the Acid Orange 7 (AO7) from water and the effect of absorption process parameters on adsorption were investigated. The results demonstrated that the efficiency of adsorption greatly influenced by solution pH and temperature. For various concentrations of dye, the equilibrium was reached at 120 minutes. Isotherm data were well adapted to the Langmuir model and maximum adsorption capacity estimated from linear Langmuir was 52.1 mg/g that was approximately twice of the rice straw adsorption capacity. The kinetics results well interpreted by pseudo second order mode, indicating chemisorption as the rate-limiting step which correspond to the interactions between the active sites of aerogel surface and the functional groups of dyes.

Many pollutants in industrial wastewaters, such as dyes, can't be removed easily by the conventional physical, biological and chemical purification processes, because of their complexity and intractability. Therefore, it is necessary to find an effective treatment technology that can degrade complex bio-refractory molecules or can breakdown them into smaller molecules which can be further degraded by conventional methods. Cavitation is one such recent technique which has been extensively studied for the treatment of complex wastewater due to its ability of generating highly reactive free radicals. Hydrodynamic cavitation has a potential of application on larger scale due to its capability in generating hydroxyl radicals at ambient condition, easy scale up and less material cost making it more economical to employ. The purpose of this study was application of hydrodynamic cavitation process for removing Reactive Black 5 and optimization the affecting parameters (pH, inlet pressure, hole diameter and initial concentration of dye) based on the amount of efficiency and energy consumption. Material and methods: In this research, removal of Reactive Black 5 with the use of hydrodynamic cavitation process was studied. 8.25 liters of colored solution was examined in each test. The cavitation was produced by orifice plate and pump. In order to optimize process, various trials were performed in pH of 3 to 11 and also using different orifice plates with hole diameter of 2, 3, 5 and 7 mm at inlet pressures of 2, 3, 4 and 5 bar and dye concentration of 30, 50 and 100 ppm. Due to the constant voltage of urban electricity, the electric current was measured as an indicator of energy consumption by ammeter. According to the results by reducing the pH, dye removal was increased and orifice plates with larger hole diameter in upper pressures had better efficiency. It was observed that increasing the initial concentration of dye resulted in decreasing dye removal efficiency. The orifice with 7 mm hole diameter at 5 bar inlet pressure yielded the highest efficiency, but by involving the amount of energy consumed and considering the process efficiency to energy consumption, the orifice with 7 mm hole diameter at 4 bar inlet pressure was chosen as the best. The pH of 3, orifice with 7 mm hole diameter at 4 bar pressure and initial concentration of 30 ppm (with regards to pump energy consumption obtained from measuring the electrical current and the efficiency of process) were selected as optimum conditions. In these conditions after 120 minutes, 38.21% dye removal was obtained using hydrodynamic cavitation. Hydrodynamic cavitation has a potential of application on larger scale due to its capability in generating hydroxyl radicals at ambient condition. It was found that the energy consumption was an effective factor in selecting the optimum conditions. By reducing the initial dye concentration and pH, dye removal was increased and orifice plates with larger hole diameter in upper pressures had better efficiency.

Colors are one of the most important pollutants of water, and only one entry into the water can significantly reduce the quality of water. In addition, due to the synthetic origin and the presence of complex molecules in the structure of colors, the purification process is sometimes accompanied by some problems. Colloidal nanoparticles play an important role in technology, especially in the manufacture of glass and ceramics, and are used as a suitable method for cleaning pollutants in water and wastewater. In this study, a chemical regeneration method was used to synthesize colloidal silver nanoparticles. Then, to evaluate the efficiency of synthetic silver nanoparticles, several solutions of dye and pigments such as sulfur, azo, reactive, cationic and anionic dyes were prepared and synthetic material was used for degradation of different colors. Finally, the effect of this colloidal nanoparticle on each of them was studied and compared. The results showed that silver colloidal nanoparticles have the ability to degradation and removal of methyl orange and methyl red dyes from aqueous samples, and these nanoparticles can be used for treatment the water and wastewater containing these dyes.

Nowadays, protecting environment, especially aqueous medium is a crucial task in modern world. Because of their nature, dyes have not only negative impacts on the aesthetic aspects of the environment, but also result in serious biological and chemical side effects on the environment. Various processes have been applied for removal of dyes from effluent. The aim of this research was to assess the removal of Cat Blue 41 from aqueous media using Fe:TiO2 in the presence of sunlight. Based on a descriptive-laboratory scale experiment using RSM design experiment, the effect of independent variables of pH, nanoparticles dosage, initial dye concentration, H2O2 concentration and contact time on the photodegradation of the dye was carried out through 26 experimental run. Analysis of the proposed model was performed using ANOVA. The proposed model for the removal of dye was statistically significant at the 95 percent confidence level. The removal efficiency was function of the independent variables of nanoparticles dosage, initial dye concentration, and contact time. The photodegradation of Cat Blue 41 showed high photodegradation efficiency of Fe:TiO2 nanoparticles under sunlight irradiation. It was found that increasing the nanomaterials dosage, contact time, and H2O2 concentration results in increasing removal efficiency so that increasing nanomaterials dosage from 0.3 to 3 g/l resulted in increasing dye removal efficiency from 48.6 to 88.9% respectively. In addition, increasing pH and initial dye concentration led into reducing removal efficiency so that increasing dye concentration from 25 to 200 mg/l resulted in decreasing its removal efficiency from 69.8 to 35.5% respectively. Therefore, design of experiment suitably optimized the removal process and reducing the number of runs resulted in increasing efficiency of the pollutant removal.

Adsorption process is proven as one of the world''s best water purification technology according to its efficiencies and widespread usage. Up to now، very valuable efforts have been done to the application of municipal and industrial solid waste usage in wastewater treatment. The use of agricultural waste is appropriate as a low cost adsorbent، based on their effect on reducing the cost of waste disposal and on helping to protect the environment. In this study، the adsorption efficiency of various agricultural wastes in removal of hazardous pollutant، such as heavy metals and organic dyes from wastewater، have been investigated. Analyzing the respective literature، it seems that the agricultural wastes have a great potential for the removal of pollutants. The related studies about heavy metals removal showed that maximum absorption efficiency was obtained by the rice husk، green pistachio peel and orange peel with more than 99 percent efficiency، and the minimum performance occurs in the pomegranate peel with 55 percent efficiency. For dyes removal، the maximum absorption efficiency was occurred by hazelnut shell، maize stem، and pistachio shell with over than 99 percent and the minimum color removal efficiency was approximately 44 percent by removal of potato peel.