نشریه شیمی و مهندسی شیمی ایران
سال سی‌ام شماره 1 (پیاپی 60، بهار 1390)

In the present research, extraction of chitin from shrimp shell was optimized. The optimized parameters consisted of temperature, reaction time and sodium hydroxide and hydrochloric acid concentrations in extraction processes including demineralization and deproteinazation. In literature, deproteinazation process before demineralization is reported, but our research revealed that the deproteinazation process after demineralization will result in higher yield. According to results, the best time and concentration for hydrochloric acid in the demineralization process are 8 h and 55 °C, respectively. The best time and concentration for sodium hydroxide in deproteinazation process are 12 h and 65 °C, respectively. We found that in the process of demineralization, use of 3N hydrochloric acid instead of 4N, 25% less uses of HCl. For the deproteinazation process 3N sodium hydroxide is the best concentration.

Biotechnical methods have the potential to offer significant improvements for traditional pulp and paper manufacturing processes due to their specificity and possible environmental advantages. Current deinking processes use large amounts of expensive, potentially environmentally damaging chemical which makes the method expensive and highly environmentally damaging. The use of enzymes could be an attractive alternative to chemicals in deinking. This research was carried out to study the influence of enzymatic deinking on optical properties and mechanical strengths of old newspaper deinked pulps. In order to perform this research, we did pulping operation with cellulase and lipase enzyme, in 4% consistency for 2.5 minutes in neutral PH, in two temperatures of 20 °C and 50 °C. After we made the pulps, we started deinking process by washing on the sieve having 120 meshes. Following this, we did statistical analyses the effect of enzymatic andtemperature treatment on optical properties and mechanical strengths of shandsheets. Results got from measuring optical properties showed that enzymatic deinking of papers leads to brightness promotion and reduces the dirt count and dirt area of handsheets. The highest brightness level and lowest dirt count and dirt area were observed in repaired samples having cellulase in 50 °C. For handsheets made from control pulp the values of folding endurance, TEA, elongation, brightness, dirt count and dirt area were 3, 34.625 J/m2, 1.74 %, 42.46 %, 51 and 1.008 mm2, respectively. On the contrary, for enzyme treated pulps the optimum values of folding endurance, TEA, elongation, brightness, dirt count and dirt area were 4, 51.54 J/m2, 2.03 %, 43.91 %, 15 and 0.245 mm2, respectively. This investigation showed that enzymatic deinking can be a suitable alternative instead of current deinking in paper recycling industries.

This paper presents a method for controlling and optimization of an oil production system using natural gas lift concept. The process of natural gas lift consists of commingled production of an oil bearing formation with a gas bearing formation. In this process, gas is entered to oil well in a controlled manner. Ever-increasing development of Smart Well technology and various applications of downhole monitoring and controlling instruments along with new methods of data transmission make it possible the natural gas lift system to be controlled and optimized more effectively and faster than before. With this technology it is possible to monitor the downhole conditions of gas and oil zones and to control the inflow valves in gas and oil zones. In this work, a Proportional Integral Differential (PID) feedback controller has been used to smartly control the entrance of gas from gas zone to oil well. The optimization of this process to determine the optimum setpoint of controller has been done by Differential Evolution method.

Simulation results of bubbling gas-solid fluidized bed using two-fluid model integrating the kinetic theory of granular flow are presented. Results of solid hold-up at different axial locations and radial directions are shown. Simulations are performed at high gas velocities. Particle motion and bubble behavior at two gas velocities of 0.35 and 0.9856 m/s in the bed are predicted and compared with the experimental data. Predicted results show that the gas velocity and ratio of the static bed height to width of the bed are important parameters for prediction of solid particles motions in a bubbling fluidized bed. Current work indicates the sensitivity of the CFD results to the drag model. Arastoopour’s drag model is the best choice for this study.At high gas velocity of 2.1824 m/s the standard k-e turbulent model and laminar models are compared. In general, the model predictions are in a good agreement with the experimental data. Current model reduces simulation’s errors compared with previous works. The minimum error is 8 % and the maximum error is 13.7 % in lower and upper part of the bed in radial direction, respectively.In addition, the error in axial direction is 4.5 %. The gas velocity values has a significant effect in solid particles motions.

In the present study saltation velocity of particles during pneumatic conveying was calculated by Computational Fluid Dynamic (CFD). The Lagrangian approach was used for particle motion. The optimum condition in pneumatic conveying is achieved by minimum energy loss. The gas and particle motion equations were solved using a finite volume discretisation and Runge-Kutta schemes respectively. The results of CFD simulations and experimental correlation for uniform particles are in good agreement (average error 17.6%). In order to study the effect of Particle Size Distribution (PSD) on saltation velocity the real PSD of injected pre- polymer into gas phase polymerization reactor was used.

In recent years, heat transfer enhancement technology has been widely applied to heat exchangers to be used in many industrial processes. By applying this technology, the need to increase the number of heat exchangers to receive higher heat rates can be ablated that economically is of great interest. In the present work, the application of three turbulators: Wire coil insert, low density matrix insert and high density matrix insert in two-phase air-water flow was investigated. The results show that these turbulators have increased the heat transfer coefficient by 26.48, 37.52 and 59.12 percentage, respectively. By comparison, there has been seen a 13.89 percentage of deviation between the experimental and choosed reference data. Moreover, from the experimental data for that abovementationed system of Insert-applied two-phase air-water flow, separately, certain new correlations were attained and evaluated.

Since The stability of methane hydrate is vital for storage and transport of natural gas, the effects of temperature and initial gas content on the dissociation rate of methane hydrate have been investigates. In order to formation of hydrate with various initial gas contents, the formation experiments have been accomplished in different condition. After formation of hydrate, the dissociation experiments have been performed at atmospheric pressure, different temperatures (ranging from 270.2 K to 262.2 K) and various initial gas in hydrate (n0=0.03 & n0=0.06). In constant temperature, the results show that the dissociation rate and instability of hydrate decreases, because an ice layer covers the hydrate surface. This phenomenon is called self-preservation effect of gas hydrate. Also the dissociation rate decreases with reduction of temperature. Increase in the initial gas content in hydrate, results in the increment of the dissociation percentage of hydrate, since the quantity of ice has been reduced in the system. A model has been developed for prediction of methane hydrate dissociation percent by correlating the experimental data received from the related experiments.

Lead is one of heavy metals.This toxic metal has more application in several industry for example, battery manufacture, tetraethyl lead manufacture, armament, paint manufacture. This wastewaters are more toxic and they vacate are more hazardous for environment, in this paper benefical of magnetite iron nano particles pollution of lead decreased up to standard (0.5ppm)andby alteration of chemical and phisycal parameters determined foremost term for adsorption of lead namely, PH, concentration of magnetite iron nano particles, temperature and designed freundlich and langmuir diagrams. at the end showed diagram industrial application. result of this research detect high removal percent of lead(70%) in the PH =5.5-6.

This report describes adsorption of hydrogen fluoride gas in a tower containing sodium fluoride pellets by using gas mixture of hydrogen fluoride and nitrogen. At the initial time of the adsorption all of the entering hydrogen fluoride was adsorbed by the tower. Adsorption of hydrogen fluoride gas on pellets is reversible. The pellets in hot conditions were regenerated without sufficient physical deterioration. Maximum loading of adsorbent is 5.96% by weight of sodium fluoride pellets. Due to low rate of adsorption kinetic, breakthrough curve is wide.

Transportation of a waxy oil from a cold environment leads to a decrease in the solubility of paraffinic component and formation of a deposit on the pipe wall. The observation of the deposit structure helps to study hardening process. The study shows that deposit structure is changed from plate shape to mal-crystals and spherulites during its growth. Based on the result, the diffusivity of wax deposit participated in hardening process was modified.

TriCalcium Phosphate (TCP) is used as suspension stabilizer in styrene polymerization process. Particle size of TCP plays an essential role in the particle size, distribution and geometric form of polystyrene product. As the particle size of TCP is reduced, there will be much better chance to surround the styrene particle. The higher the number of TCP particles surrounding each styrene particle, the lesser will be their tendency to form a large particle after collision. Therefore the percentage of spherical polystyrene with small particle size and narrow distribution in the product are increased. In this study addition of polyphosphate salts and nacconol to the reaction mixture of TCP precipitation process and their effect on the particle size of TCP are investigated. The result show that addition of sodium hexa metaphosphate to the reaction mixture decreases the crystal growth rate and prevents precipitates to agglomerate. So the mean particles size of TCP is reduced from 5µm (without SHMP) to 1.5 µm (with SHMP).

In this research work, The methoxy- m-Terphenyls are demethylated with boron tribromide solution in dichloromethane.The methoxy - m -Terphenyls required, are prepared from the reaction of methoxy- aryl- grignards with 2, 6- dichloroiodobenzene in refluxing THF. The hydroxy- m- Terphenyls can be used for the preparing polyesters, polyethers, cyclophanes, benzoquinones and other derivatives of Terphenyls.