جستجوی مقالات مرتبط با کلیدواژه "recovery" در نشریات گروه "مهندسی شیمی، نفت و پلیمر"

Energy and the environment are two important parameters in the development of countries. The flaring system is the main way to waste energy in refineries and operation units, which emits the highest amount of environmental pollutants. Large volumes of associated gases are of high fuel value. Therefore, paying attention to this section's reuse, performance, and modification is of great importance. In this study, Aspen HYSYS software was used. The combination of incoming gas to flare from the Ahvaz refinery was considered. Sweetening was done with methyl diethanolamine and piperazine. Then, the dehydrate was performed with triethylene glycol. Sweetened gas sent to LNG unit. The results of the output of the software show that the separation of carbon dioxide by 99.99% and hydrogen sulfide by 99.94% has been done. When the gas enters from the bottom of the absorption tower, i.e. tray number 20, it has severe temperature changes from 33.6 °C to 54.5 °C, which can be due to the selective absorption of H2S in the presence of CO2 by MDEA and the polarity of H2S. The movement of gas to the top of the tower is accompanied by an increase in temperature up to tray 19, whose temperature has reached 57.7 °C, which is due to the greatest absorption and mass transfer that has occurred in this tray. From tray 19 to tray 13, absorption and temperature decrease until the system reaches equilibrium. As a result, exhaust gas can be considered sweet gas. LNG production capacity in the liquefy unit is 386,700 kg/h, which economically can have a net profit of 32136,000 $ per year.

Leaching and recovery parameters controlling the releasing of selenium from Sar-Cheshmeh copper anode slimes are studied and determined.

Copper anode slimes is produced during the production of cathodic copper at the bottom of electrolyte cells, which is composed of insoluble anode components in the electrolyte. The copper anode slimes are made up of those components of the anodes, which are not soluble in the electrolyte. They contain varying quantities of precious metals like gold, silver, selenium and tellurium, and other precious metals in the anodic copper. They are being extracted as a by-product in the copper production process. Due to the fact that the main source of selenium is sulfur deposits such as copper and nickel. Copper anodic slimes is currently the only source of selenium in the world. In this study, the extraction of selenium from anodic copper slimes has been feasible. To do this, acid leaching has been used. Copper anodic sludge is the raw material for the production of more than 90% of the world selenium and is the main source of selenium production.[1-3]

In this paper, the effect of operational parameters such as acid concentration, temperature, process time and liquid to solid ratio on selenium recovery through copper slimes leaching was investigated. The optimum conditions of batch leaching For maximum selenium extraction from anodic copper slimes are attained at 3 mol L-1 of HNO3 concentration, 0.01 (W/V) solid to liquid ratio for 60 min contact time at 70 º C. Under the optimized conditions, the selenium leaching efficiency was 99%. The thermodynamic data showed positive values of both ΔH and ΔS which indicates that the leaching process is indeed endothermic and random while the obtained negative values of ΔG show that selenium dissolution process is spontaneous in nature.

Heavy metal ions (e.g., Cd2+, Pb2+, Cu2+, Mg2+) and organic pollutants (like dyes) present in industrial wastewaters are one of the major causes of pollution of groundwater sources. These pollutants are toxic to humans, plants and aquatic life and should be removed from wastewater before disposal. Various treatment technologies have been reported to treat pollutants from aqueous media, such as coagulation and flocculation, oxidation, membrane filtration, and adsorption. Most of these methods are associated with some shortcomings and challenges in terms of applicability, efficiency, and cost. Based on economical aspect, flexibility and simplicity of design, and availability of wide range of adsorbents, adsorption is recommended as an effective method for removal of organic/inorganic pollutants from aqueous media. Hydrogels are three-dimensional flexible polymeric networks with extensive applications in the biomedical, pharmaceutical, agriculture, biotechnology and separation processes fields. Due to the unique physical and chemical characteristics of hydrogels, such as hydrophilicity, swelling ability, high adsorption capacity, the presence of various specific functional groups and modifiability, an increasing research interest in the development and application of novel hydrogels in water and wastewater treatment has emerged. Hydrogels have exhibited superior performance in the adsorptive removal of a wide range of aqueous pollutants including heavy metals and toxic dyes. Due to the lack of an overview on applications of hydrogels in adsorption of pollutants, this review investigates the different steps involved in the hydrogel-based treatment systems, the influencing factors and mechanisms of pollutants removal. Major challenges about adsorption kinetics, operational pH range, interference, and hydrogel recovery are discussed. Finally, important considerations like stability, reusability of hydrogels and resource recovery are discussed for economic and sustainability concerns.

Machine-woven carpets are pile fabrics. Warp and weft yarns are used for making the backing surface an piles (i.e., upright loops or strands of yarns) are covering the upper surface of carpets. In this study, the relations between structural parameters of machine-woven carpets namely weft and warp yarns density, pile yarns count and kind of warp yarn denting with recovery after dynamic loading, thickness variation in static loading and finally the mass variation during the hexapod walker carpet tester were evaluated. Two pile yar counts (i.e. 18/3 Nm and 33/3 Nm), two levels of warp density 700 and 1200 per meter, two kind of dentin of warp yarn (i.e. one and two warp yarns per dent), and three levels of weft density (i.e., 2550,3000, and 350 per meter) were used to produce the samples. The results showed that the highest value of compressibility in dynamic loading was varied between 40.16% and 23.97%. The lowest value of mass variation in tetrapod walker testing was obtained in sample woven with highest value of warp and weft density. Moreover, bincreasing the count of pile yarn and the initial thickness of sample, the mass reduction was increased accordingly.

The combination of extraction methods and oxidative desulfurization due to high efficiency and good operating conditions can be considered as a viable alternative for conventional desulfurization methods. In this study, the oxidation/extraction desulfurization method was investigated to remove sulfur-containing compounds from gasoil fuel. Gasoil with a total sulfur content of 1550 ppm was selected as feed. Hydrogen peroxide-formic acid system was used as the oxidation system. The gasoil desulfurization and recovery after oxidation were 96.38% and 20.64%, respectively. Three polar solvents (i.e., acetonitrile, dimethylsulfoxide and dimethylformamide) were considered as potential candidates for the extraction of oxidized sulfur-containing compounds from gas oil. Acetonitrile solvent was rejected due to its low density close to gasoil density. Thus, the effect of solvent to fuel ratio (0.5-2) and number of extraction stages (1-3) were investigated for dimethylsulfoxide and dimethylformamide. It was found that the achieved desulfurization for dimethylformamide was higher than that of dimethylsulfoxide. But, the gasoil recovery after the extraction was higher for dimethylsulfoxide in comparison with dimethylformamide. The highest gasoil desulfurization and recovery were obtained 97% and 96%, respectively.

In recent years the market demand for electronic instruments with attention to their low life time is increasing rapidly which create a new environmental challenge. E-waste contains a vast range of hazardous metals which an improper management can threat human society seriously. On the other hand on average e-waste can supply about 40 million ton of materials. But the complex and non heterogeneous nature of this waste was the main barrier for recycling. Traditional methods are highly cost and produce hazardous intermediate material. Bioleaching is environmental-friendly and economical for recovery of metals from e-waste by using microorganisms such as bacteria and fungi. In this article, previous articles about bioleaching of e-waste are studied. The result showed bioleaching is an effective method for metal extraction from e-waste. Some base metals as like as Cu, Ni, and Zn were extracted totally and Au, a stable metal, can recovered about 50%.

The numerous applications and high cost of platinum group metals (PGMs), in addition to the scarcity of their sources and mines, has led the secondary sources of these metals to a high consideration. In this study, the hydrometallurgical recovery of platinum from spent catalysts was investigated. For this purpose, after the preparation and grinding, the catalysts were dissolved in HCl and HNO3, as an oxidant. Extraction of platinum from acidic solution was performed by magnetite nanoparticles. Firstly, the magnetite nanoparticles were synthesized by co-precipitation of ferrous and ferric salts in the presence of ammonium hydroxide. Because of the instability and tendency to agglomeration, the surface of nanoparticles was coated by tetraethyl silicate. Subsequently, the silica-coated nanoparticles were functionalized with diphenyl phosphine ligand, that had the ability to selective adsorption of Pt. Finally, in a time less than 15 minutes about 91% [PtCl4]2- was recovered from leach liquor.

Recovery of cobalt(II) from aqueous solution by polymer inclusion membrane with dinonyl-naphtalenesulfonic acid (DNNSA) as the ion carrier and plasticized with 4 different plasticizer was investigated. Carrier concentration as an important parameter in recovery efficiency was studied and the membrane composed of 15% (wt/wt) of carrier was found to be the most efficient. The studies included effects of nature of plasticizers. Transport accross membranes plasticized with dioctyl adipate, dioctyl phthalate, triethyl phosphate, tributyl phosphate in 8 hours were investigated and dioctyl adipate was selected as the best. The FTIR characterization showed that the membrane constituents remains as pure substance after synthesis. Recovery of cobalt(II) ions increased with increasing of rate of mixing up to 200 rpm and after that became constant. The effect of pH on recovery was investigated between 3-7.5 and the most efficient pH was 5. Finally, the kinetics was studied with optimized parameters by investigation of cobalt concentration of source phase as a function of time and were found to follow first-order kinetics.