جستجوی مقالات مرتبط با کلیدواژه « تبادل یونی » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

In recent years, low salinity water-flooding has received much attention as one of the enhanced oil recovery methods because of its cheapness and low operating limitations. Tuning of injected water composition and concentration can induce a significant effect on the oil recovery during the spontaneous imbibition process and forced oil displacement in the fractured reservoirs. Numerous lab and field studies have been conducted to realize the mechanisms and factors affecting the low salinity and smart water injection. Despite these researches, some of the related mechanisms and determining factors in carbonate reservoirs, such as the initial water saturation and temperature, have not yet been fully understood. Therefore, extensive experiments are needed to optimize the conditions of injected water. In this study, the oil recovery of spontaneous imbibition by low salinity and smart water containing divalent ions has been investigated when the initial water saturations were in relatively small and high amounts in carbonate cores. Then, the coreflooding experiments were conducted with various temperatures, including equivalent and below the reservoir temperature. Based on relative permeability and capillary pressure measurements, the mechanism leading to higher oil recovery during smart water injection was also investigated. The results showed that the oil recovery was increased during spontaneous imbibition of low salinity and smart water under ambient conditions as the initial water saturation increased. It was also observed that elevating the temperature from 80 °C to 105 °C in secondary water injection could improve oil production significantly. The reduction of residual oil saturation in the relative permeability and capillary pressure diagrams due to the presence of sulfate and magnesium ions confirmed that the carbonate rock became more water-wet at the ambient temperature.

In the present research, the photocatalytic water splitting process has been carried out over titania nanoparticles immobilized on parent clinoptilolite and ion exchange-treated clinoptilolite with the aim of understanding the effects of chemical treatment method on the physicochemical properties and performance of catalyst, and assessing the effects of operational parameters including irradiation time, photocatalyst dosage and solution pH. To this aim, 10 wt.% of TiO2 nanoparticles were loaded over zeolitic supports using facile and cost effective solid state dispersion (SSD) method. Moreover, the synthesized photocatalysts were characterized by XRD, FESEM, EDX, BET, PL and UV-vis techniques. The characterization results indicate that less population of surface particle aggregates, a better dispersion of titania particles and stronger metal-support interaction as a result of higher surface area and more accessibility of the zeolite micro-channels were achieved using modified clinoptilolite support. The fine dispersion of TiO2 particles reflects higher surface density of active sites and separation efficiency of electron-hole pairs, which accounts for their better photocatalytic performance. Employing the ion exchange- treated clinoptilolite as support led to 30% increase in the photocatalytic activity of TiO2-treated clinoptilolite for hydrogen evolution compared to that of TiO2-based composite containing the bare clinoptilolite. By assessing the influence of the operational conditions on the efficiency of water splitting, a maximum hydrogen evolution (859.74 µmol g-1 h-1) was obtained with optimum condition set at irradiation time of 4 h, solution pH of 10 and photocatalyst dosage of 1 g L-1, which is about 12 times greater than that of pure TiO2 as the reference sample.

Recovery of the nobel metals, platinum and rhenium, from a spent aromatization catalyst of naphta is reported, using ion exchange method by anion exchange resin.The catalyst is soluted in a mixture of some acids and the produced solution is passed through a column which contain the ion exchange resin. The platinum and rhenium that exist in the solution are absorbed by the resin, then the resin is washed by means of a suitable acid. platinum and rhenium thus leave the resin and come into solution again. Various parameters which affect the process of elution and absorption are also studied and the optimum conditions for maximum recovery are determined. The efficiency is 100 % in the absorption process and over 95 % in the disorption process.

Adsorption process is one of important separation processes for recovery of organic acids with ion exchange resins. Generally ion-exchange resins are made on matrix non soluble long polymer, usually polystyrene. The results have indicated among strongly anionic resins, Amberlite IRA-400 is suitable for recovery of Lactic Acid. In the present work, efficiency of lactic acid recovery in 10/40 chromatographic column in 45 °C was studied. Also the effect of volumetric flow rate for washing of resin with distilled water and normal sulfuric acid and the recovery efficiency was obtained. Generally the results have indicated in the best volumetric flow rate, the recovery efficiency was obtained almost 96%.