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In current research, Pseudomonas putida @ Chitosan hybrid biosorbent capability for U(VI) biosorption in a fixed bed column was investigated. The results showed that the increase in inlet concentration from 50 to 200 mg/L increased the biosorption capacity from 188.75 to 429.28 mg/g. In the column system, the sorption capacity was higher than that of the batch system because fixed bed column make best use of the inlet concentration difference as sorption driving force. Decrease in inlet flow rate through increase in the residence time for better diffusion or interaction as well as greater access to binding sites for uranium ions caused an improvement in column performance. Decline in the biosorption capacity due to increase in the inlet flow rate demonstrated that intraparticle diffusion was the rate-controlling step. With decreasing in the sorbent particle size from 1.5 to 1 mm, a significant increase in the biosorption capacity from 179.02 to 296.87 mg/g was achieved. FTIR and potentiometric titration confirmed that while –NH₃⁺ was the dominant functional group in the chitosan, –NH₃⁺, –NH₃, –OH, –COOH were responsible for the hybrid biosorbent. In conclusion, the present study indicated that Pseudomonas putida @ Chitosan could be a suitable biosorbent for U(VI) biosorption from aqueous solution in the continuous system.

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The enhancement of energy consumption and increasing demand for oil have led to using improve oil recovery methods. Chemical enhanced oil recovery methods are among the most widly used techniques. Generally, the effect of these methods has been less than the predicted amounts by the studies. One of the leading causes, could be due to the loss of chemicals by adsorption or precipitation of the surfactants on the rock surface. The mineralogy of the reservoir rocks is effective in determination of the interaction between the bulk of the fluid phase and rock surface. This effect will change in the surface charge of the adsorbent and wettability alteration of the rocks.
Research subject: In this study, the adsorption of AOT surfactant on the surface of a hydrophilic adsorbent of carbonate reservoir was investigated. For this purpose, after the preparation of rock and fluid samples, the adsorption of surfactant was investigated in concentrations below and above the CMC.
Research approach: Batch adsorption experiments were conducted to measure the amount of surfactant adsorption on the surface of carbonate rock. First different concenteration of AOT solutions and carbonate rock as adsorbent were combined. After 48h, the equilibrium concentrations were determined by using the calibration curve and. The amount of surfactant adsorption can be calculated by knowing the maqnitudes of  equilibrium and initial concentration of the surfactant.

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Research subject: In this study, the occurrence of flooding due to the accumulation of sediment in the downcomer area, which led to an excessive increase in liquid on the upper trays of the distillation column was investigated in a refinery.
Research approach: Vacuum pressure in the upper area of the column, boiler feed water flow from the inlet to the condenser and the discharge of the net product as three very important and effective operational parameters in controlling the severity of the flooding phenomena and the amount of coking value as an important laboratory parameter to reduce the volume of inlet sediments entering the distillation column. Data and results of changes made on each of these three operational parameters showed their effectiveness in controlling the severity of the flooding phenomena.
Main results: In order to control and reduce the problems caused by the simultaneous flooding phenomena around the vacuum pump, the boiler feed water flow of the inlet to the condenser and the flow of the net output product were proportionally increased until the operating conditions of the distillation column are normalized. In this study, how to control the flooding phenomena and reduce the adverse effects due to the accumulation of sediments in the downcomer area of tray No. 22 and above was investigated.
To overcome these problems, first the vacuum pump rotation speed was increased from 850 rpm to 1250 rpm and the boiler feed water inlet to the condenser from 1.95 m³/hr to 3.2 m³/hr was increased. On the other hand, in order to prevent contamination of the pure product, the net output product flow rate also increased from 925 kg/hr to 2300 kg/hr. Also, with regular and accurate control of the coking value index as a very important laboratory parameter, the volume of coke sediments in the coal tar feed entering the distillation column was reduced from 37.5% by weight to 18.4% in a 30-day period after centrifugation.

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Research subject: Nowadays, due to the prevalence of coronavirus and the increasing use of disinfectant solutions and gels, the use of glycerin has also increased dramatically. But the suggested processes in this field need to be optimized in terms of production and energy consumption.

Research approach: In this paper, the transesterification method has studied and simulated, during which vegetable oil is converted into biofuel, and glycerin is also produced as a by-product of this process. For this purpose, process simulation of a conventional unit with 5.5 m³/min feed has been done in Hysys. Also, due to the importance of equipping the transesterification reactor, by importing the necessary process information, this equipment has been simulated in COMSOL MultiPhysics and the effective parameters have been studied in order to optimize the of product conversion. After validation of model, to better understand the factors affecting the performance of the transesterification reactor, the effect of selected parameters first examined by one-variable at the time design of experiment approach.
Main result: Finally, it has been shown that the feed temperature and the flowrate both have significance impact on quantity and quality of product and while providing a model for calculating the amount of glycerol produced per unit of energy consumed, the effective parameters are optimized by the response surface method. In optimal conditions of the ratio of product production to energy consumption, the temperature value was 470.7 K and the feed flow rate was 0.586 m³/s. According to the gained results, it can be obtained by adjusting the flow rate in the optimal amount, using a preheater in the production processes of biofuels and glycerin can have a significant effect on the amount of products produced so that the optimal temperature for the output of this preheater is at least 470.7 K should be considered. In the current research an optimization scheme has been suggested which can be used for different Biodiesel-Glycerol production units with varies range of flowrate.
 

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Research subject: Bio-hydrogen is a renewable energy source with many economic and environmental benefits as a fuel. Controlling the concentration of the substrate in the reactor has a significant effect on the amount of hydrogen production. However, bio-hydrogen production is a nonlinear process that requires the implementation of nonlinear control methods. In this paper, substrate concentration in an anaerobic bio-reactor is controlled using the feedback linearization method.
Research approach: The model employed for the simulation is a well-known model consisting of three state variables. The proposed controller is a globally linearized controller (GLC) designed based on the feedback linearization technique. In this method, the nonlinear system is precisely linearized by a transformation of the coordinate system. As a result, the linearized system can be controlled using a linear controller. In order to linearize the system, a nonlinear compensator is designed using the design model and applying the concepts of differential geometry. Proportional-integral (PI) controller is adopted as a linear controller. GLC controller performance has been compared with a nonlinear controller (NC) and a PI controller. The performance of these controllers has been studied by numerical simulation based on the integral of time-square error (ITSE).
Main results: The simulation results show that substrate concentration control can contribute to the hydrogen production. The control method applied has better set-point tracking than the other two control approaches. The ITSE performance index for the feedback linearization method is lower than the other two methods. The nonlinear feedback controller fails if the kinetic parameters are changed by 25%, but the PI method and the feedback linearization are robust against model uncertainty. An efficient controller guarantees stable bio-hydrogen production. Comparing open-loop and closed-loop simulation results shows that controlling the substrate concentration increases hydrogen production by 90%.

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Abstract
Research subject: The combustion of fossil fuels to supply energy produces large amounts of carbon dioxide. Carbon dioxide emissions have led to rising global temperature and many natural disasters, including floods, hurricanes, rising sea levels, and widespread droughts, that threaten ecological systems and human life. Therefore, the uptake and removal of carbon dioxide from sources or the environment play a key role in countering the threat of global warming.
Research approach: In this study, a venturi scrubber was utilized to eliminate CO2 from the air stream on a semi-industrial scale. The effects of different parameters including inlet air flow rate to the venturi scrubber, solvent flow rate, and solvent loss during the scrubbing process were investigated on CO2 absorption by a nanofluid solvent containing iron oxide/water at the presence of tetramethylammonium hydroxide (TMAH) as a surface-active material.
Main results: The surface-active material of TMAH prevents the agglomeration of nanoparticles in the base fluid and stabilizes the fluid. The maximum efficiency of absorption and the highest molar flux of CO2 were achieved when iron oxide nanoparticles were used along with graphene nanosheets with the ratios of iron oxide nanoparticles (25%) and graphene nanosheets (75%) at the presence of TMAH surface-active material due to their nature. The reason is the better agitation (of the solution) by iron oxide nanoparticles that results in an increased displacement of graphene nanosheets. The random Brownian movements of nanoparticles create micron size eddies that increase mass transfer at the gas-liquid interface. In addition, molar flux and CO2 gas absorption efficiency decreased by increasing the concentration of nanoparticles.
Keywords: Hybrid nanofluid; Venturi scrubber; Gas absorption; Iron oxide nanoparticles; Graphene nanosheets

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Subject
Petroleum coke calcination is a chemical process during which the petroleum coke loses moisture and volatile combustible materials due to the increase in temperature and ultimately improves the physical properties of the calcined coke. In this study, A 2-Dim model was developed for the petroleum coke calcination process via rotary kiln using the CFD approach. Understanding the temperature, concentration, and fluid movement behavior are the main goals for developing the simulation model, by using which the rotary kiln control and design can be performed.
Methodology
Comsol Multiphysics was applied to develop the simulation model. Petroleum coke rotary kiln calcination consists of two solid and gas phases, which cross each other counter-currently. All governing physics in the system, including chemical reactions, heat transfer via conduction, convection, and radiation, intra-phase and interphase mass transfer, evaporation or evolution of components from the solid phase into the gas phase, fluid turbulency and all complex relationships were considered. Using the finite element method, the governing equations of the model were solved, and consequently, the variation of temperature, components concentration, and fluid velocity was calculated.
The main results
It is concluded that tertiary air injection significantly affects the temperature profile and combustion reactions in the bed (About 100 degrees increase in temperature). In addition, the maximum temperature of 1910 °C has been achieved in the kiln. Concentration changes of components in the gas phase were also seen mainly in the bed entrance and in the areas near the tertiary air injection. Comparing the results with similar works showed the high accuracy of the developed model