Modeling of Activated Sludge Process Using Sequential Adaptive Neuro-fuzzy Inference System

In this study, an adaptive neuro-fuzzy inference system (ANFIS) has been applied to model activated sludge wastewater treatment process of Mobin petrochemical company. The correlation coefficients between the input variables and the output variable were calculated to determine the input with the highest influence on the output (the quality of the outlet flow) in order to compare three neuro-fuzzy structures with different number of parameters. The predictions of the neuro-fuzzy models were compared with those of multilayer artificial neural network models with similar structure. The comparison indicated that both methods resulted in flexible, robust and effective models for the activated sludge system. Moreover, the root mean square of the error for neuro-fuzzy and neural network models were 5.14 and 6.59, respectively, which means the former is the superior method

An Experimental Investigation of Reactive Absorption of Carbon Dioxide into an Aqueous NH3/H2O/NaOH Solution

In this research, the reactive absorption of carbon dioxide in an aqueous solution of NH3, H2O, and NaOH has experimentally been investigated. The experiments were carried out in an absorption pilot plant in different operational conditions. The composition and temperature of both gas and liquid phases were obtained during the column height. The concentration of molecular and ionic species in the liquid phase was calculated using the principles of electrolyte and Pitzer model. In the experiments, the effect of sodium hydroxide concentration on carbon dioxide absorption was considered. The results revealed that the concentrations of ionic and molecular species in the liquid phase drastically influence the absorption rate of carbon dioxide. Also, the results showed that the absorption rate of carbon dioxide was increased by increasing ammonia and sodium hydroxide concentration

Improved structure of Zr-BTC metal organic framework using NH2 to enhance CO2 adsorption performance

Abstract Modified mesoporous NH2-Zr-BTC mixed ligand MOF nanocomposites were synthesized via the hydrothermal method as a novel adsorbent for CO2 capture. The newly modified MOF-808 with NH2 demonstrated a similar mesoporous morphology as MOF-808, whereas the specific surface area, pore volume, and average particle size, respectively, increased by 15%, 6%, and 46% compared to those of MOF-808. The characterization analyses exhibited the formation of more active groups on the adsorbent surface after modification. In addition, a laboratory adsorption setup was used to evaluate the effect of temperature, pressure, and NH2 content on the CO2 adsorption capacity in the range of 25–65 °C, 1–9 bar, and 0–20 wt%, respectively. An increase in pressure and a decrease in temperature enhanced the adsorption capacity. The highest equilibrium adsorption capacity of 369.11 mg/g was achieved at 25 °C, 9 bar, and 20 wt% NH2. By adding 20 wt% NH2, the maximum adsorption capacity calculated by the Langmuir model increased by about 4% compared to that of pure MOF-808. Moreover, Ritchie second-order and Sips models were the best-fitted models to predict the kinetics and isotherm data of CO2 adsorption capacity with the high correlation coefficient (R 2 > 0.99) and AARE% of less than 0.1. The ΔH°, ΔS°, and ΔG° values were − 17.360 kJ/mol, − 0.028 kJ/mol K, and − 8.975 kJ/mol, respectively, demonstrating a spontaneous, exothermic, and physical adsorption process. Furthermore, the capacity of MH-20% sample decreased from 279.05 to 257.56 mg/g after 15 cycles, verifying excellent stability of the prepared mix-ligand MOF sorbent

The effects of operating parameters on stage efficiency in an Oldshue-Rushton column

In this research, stage efficiency has been measured in a 113 mm Oldshue-Rushton column for two systems including toluene-acetone-water and n-butyl acetate-acetone-water. The experiments performed in two directions of mass transfer. The effects of different parameters such as rotor speed, dispersed and continuous phase velocities and direction of mass transfer on the stage efficiency were investigated. The experimental data show that the stage efficiency is strongly dependent on the agitation rate and interfacial tension, but only slightly dependent on phase velocities. It was observed that the stage efficiency is better when the mass transfer direction of acetone is from the continuous to the dispersed phase in comparison to opposite direction due to the presence of oscillations created by surface tension gradient. The investigated column is one of the extraction columns with high stage efficiency. An empirical correlation is proposed to describe the stage efficiency in terms of Reynolds and Froude numbers. The predictions of the equation had good agreement with the experimental data

Investigation of Salt and precipitating agent effect on the specific surface area and compressive strength of alumina catalyst support

Nowadays, catalyst supports are extensively used to decrease the costs and increase the contact surface area in chemical reactions. Specific surface area, compressive strength, pore volume and pore size are some of the most important characteristics of a catalyst support. In this work, Sol-gel and peptization methods were applied to produce alumina catalyst support. Also the roles of aluminum salts and precipitating agents on the specific surface area and compressive strength of alumina catalyst support were investigated. In addition, various additives and common methods in the increasing surface area, compressive strength and adjusting the porosity and pore size are used in this study. The results show that using caustic soda as precipitating agent and aluminum chloride salt yields catalyst supports with the best compressive strength. Also, using aluminum nitrate and ammonia as precipitating agent produced alumina catalyst support with the highest specific surface area