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

SnO2 nanoparticles were first synthesized using a grape extract media, then characterized by XRD, FE-SEM, TEM, BET, and DLS techniques, and finally used as an efficient adsorbent for the removal of Pb2+ and Cd2+ ions from wastewater. The prepared sample had a tetragonal phase with an average crystallite size of 41 nm (XRD analysis), a specific surface area of 47.08 m2.g-1 (BET method)/46.25 m2.g-1 (BJH method), and a pore diameter of 6.49 nm (BJH method). The best conditions for adsorbing were a 30 ppm concentration of metal ions, ambient temperature, pH of 6, and 0.025 g of an adsorbent. The maximum adsorption for Pb and Cd ions was 97 and 93%, respectively. The Elovich model was matched as the most suitable kinetic model, indicating that the adsorption mechanism is chemical adsorption. The negative values of ΔG (Pb: -6.38 kJ.mol-1; Cd: -4.16 kJ.mol-1) represent the spontaneousness of the adsorption process. The negative values of the parameters ΔH (Pb: -63.0 kJ.mol-1; Cd: -42.95  kJ.mol-1) and ΔS (Pb: -188.8 J.mol-1; Cd: -128.4 J.mol-1) represent the exothermic nature of the adsorption.

Methanol is an important industrial chemical, and its synthesis and purification units are among the most widely used processes in the field of energy. The two-column separation unit of methanol has been analyzed from the thermodynamic and energy points of view in the present study. The simulation has been done by Aspen Hysys V11 and the SRK equation has been regarded as the most appropriate equation of state (EOS) for this simulation with the mean relative error (MRE) of 2 %. Then, the design of the heat exchanger network (HEN) has been calculated using the Aspen Energy Analyzer V11. Both distillation towers have been analyzed using pinch technology. As a result, the amount of hot and cold utilities used has been LP=1.482×〖10〗^8, MP=1.57×〖10〗^4, and Air =1.423×〖10〗^8, respectively. Besides, the total heating and cooling target of the process has been 1.482×〖10〗^8 and 1.423×〖10〗^8, accordingly. Then, the 〖∆T〗_min (minimum allowable temperature difference between hot and cold currents) and its effect on the annual cost have been investigated. The optimum value 〖∆T〗_min is determined to have better-operating conditions and to meet the design of the HEN economically. Reducing 〖∆T〗_min increases operating costs and reduces energy costs.

This paper presents a combined thermodynamic, economic, and environmental comparison of different configurations for co-production of power and desalinated water. Each configuration is analyzed both with inlet air cooling and without inlet air cooling. The most eminent characteristics for the comparison are cost of produced power, cost of produced water, total annual profit, CO2 emission, and CHP efficiency. The common portions of all configurations are the gas turbine and the desalination system. The primary distinctions between scenarios are arrangement and type of system components. Thermodynamic simulation determines mass flow rate of high pressure and low pressure steam, as well as net power and water production of each configuration. Economic simulation reveals the price of produced power, the price of produced water and the total annual profit of the plant. Also, Environmental analysis specifies the total CO2 emission per annum. Final results show that the third configuration, in which a double-pressure HRSG is utilized, has the lowest CO2 emission per MWh of produced electricity. Also, it is concluded that the second configuration, in which a single-pressure HRSG is utilized, has the lowest specific fuel consumption and consequently the highest CHP efficiency. Sensitivity analysis shows that increasing the inlet air temperature will increase the specific CO2 emission in the second configuration. On the other hand, inlet air temperature increase has a marginal impact on CO2 emission in the first and the third configurations. The economic analysis shows that the first scenario with inlet air cooling has the highest total annual profit.

In this study, Kaolin, Bentonite, and Feldspar were used as a low-cost source of Si and Al to synthesize the molecular sieve 13X. The synthesized Zeolites were characterized by XRD, FTIR, SEM, TGA, and BET analysis and used as a suitable adsorbent for CH4 adsorption. The surface areas were 591, 505, 472, and 588 m2/g for natural kaolin (13X-K), bentonite (13X-B), feldspar (13X-F) and commercial molecular sieve 13X (13X–C), respectively. The 13X-K had the highest thermal stability than 13X-B and 13X-F. The adsorption capacities (pressure >20bar) of 13X (kaolin), 13X (bentonite), and 13X(feldspar) were 3.6, 2.4, and 1.95 mmol/g, respectively. The adsorption data were fitted to some isotherms including Langmuir, Freundlich, Sips, BET, and Toth. It was found that the Sips model showed better fitting in comparison to other models. The thermodynamic of adsorption was also investigated; the positive value of ∆S_ads^0 revealed the increased randomness at the solid-solution interface during the gas adsorption. The thermodynamic study also indicated that the adsorption process was exothermic and spontaneous. The adsorption capacities of synthesized 13X samples were compared to other adsorbents; it was found that 13X–K showed considerable performance and can be introduced as a suitable adsorbent for applications on a large scale.

The removal of dyes from wastewater, is one of the major environmental concerns due to their high color density, and they are toxic at even low concentrations. Adsorption process by advanced oxidation processes (AOPs) has been found to be a more effective method than classical methods for treating dye-containing wastewater. This research, is to investigate the decolorization abilities of azo dye in order to treat organic polluted wastewaters efficiently by AOPs. Various operational parameters such as pH, initial dye concentration and catalyst loading were investigated on the use of ZnO/W in the adsorption of Reactive Red 31 (RR 31) dye. The study also focused on the kinetic and thermodynamic investigation such as activation energy (Ea), standard Gibbs free energy (ΔG0), standard enthalpy (ΔH0), and standard entropy (ΔS0). The kinetics of adsorption of dye followed a pseudo-first order kinetic model. Further, thermodynamic study showed that the photocatalytic decolorization of this dye is an endothermic and spontaneous reaction. This study represents a success of thermodynamic for the application in environmental area. Additionally, cost analysis of the process was discussed. The treatment effectiveness was reported as the electrical energy consumed per unit volume (EEO) of waste-water treated required for 100% decolorization of the investigated compound.

In this study, the adsorption of Reactive blue 19 onto pomegranate residualbased activated carbon was investigated in aqueous solution. The activated carbon prepared by phosphoric acid activation under air condition. PRAC was characterized for its surface chemistry by point of zero charge measurements, Scanning Electron Microscopy and nitrogen adsorption at 77 K. The effect of operational parameters including contact time, initial pH, adsorbent dose, initial dye concentration and particle size were studied. Results showed that an optimum dye removal efficiency (96.7%) was observed at initial pH=11, contact time of 5 min, adsorbent dose of 3.25 g/L, initial dye concentration of 200 mg/L, and particle size of 63-149μm. The adsorption process was found to follow the Temkin isotherm equation (R2=0.975) and second-order kinetic model (R2=0.999). Furthermore, thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated.