Iranian Journal of Chemistry and Chemical Engineering
Volume:42 Issue: 2, Feb 2023

In this computational research, the solvent effect is probed on HDAL of C20 with I to yield Ia compound. So, in going from the gas phase to non-polar, and in turn to the polar solvent, a good consistency appears between the dielectric constant of the solvent (ε) and the released solvation energy (∆El-g). The stability and polarity of Ia appearances are proportional to ε, and the probability of the H-bonding. While the obtained endo-isomer from HDAL is anticipated thermodynamically more stable than exo- analogue; here we found that the formation of exo-isomer is only the obtained product from this HDAL. Subsequently, exo-isomer is more stable than endo-analogue; due to the disappearance of the resulting electronic effect and ring-strain effect from π-stacking between the aromatic rings of I and nanocage. The possibility of HDAL is ruled out by the lowest energy barrier of 5.1 kcal/mol probed for exo Transition State (TS) in the gas phase, while the highest energy barrier of 9.4 kcal/mol is investigated for endo TS in H2O. Hence, the designed HDAL is distinguished as an attractive and promising procedure for ligation in biochemistry due to its higher rate and selectivity in H2O. Fascinatingly, similar to stable C60 nanostructure, exo HDAL of unstable C20 nanostructure with the scrutinized diene can be carried out thermally at room temperature and may be a potential candidate for efficient and selective HDAL in living systems. 

Cyanidation of gold depends on the amount of oxygen in the reaction medium. In this study, the interaction of O2 molecules with crystalline surfaces of gold (110surf0 and 110surf+1 surfaces) is investigated by using density functional theory (DFT). The results showed that the interaction of O2 with Au2 cluster was weak, which leads to overlapping orbitals of the 5dz2-Au and the pz-O2. Oxygen reacts vertically with the surface was almost similar to its reaction with the Au2 cluster. However, the parallel interaction of O2 on the (110surf0) and (110surf+1) surfaces of Au is stronger than the vertical interaction state. Also, the interaction energy of CN- with (110surf+1) surface obtained about 13 kJ/mol more than (110surf0) surface.

A series of Nb2O5/SiO2 catalysts with varying Nb2O5 loadings (5–25 wt%) were prepared using the sol-gel technique. The catalytic activity of the materials was evaluated by nitration of toluene. Nb2O5/SiO2 catalyst showed good catalytic activity, selectivity, and reusability for the nitration of toluene. Under the optimal conditions, conversion of toluene by 86% to mono-nitrotoluene was achieved with 100% selectivity. Experiments were designed by Minitab software, and the effect of reaction conditions was examined on the amount of meta isomer. The optimal reaction condition was also achieved for the lowest amount of meta isomer using this software. The reusability of the catalyst also was studied in this work at the same operating conditions, and the catalyst was stable for four runs without losing catalytic activity.

Three organotin carboxylate complexes were synthesized by condensation of the reaction of methanolic tryptophan solution with Tri, and Diorganotin chloride for 3-4 hours to obtain the corresponding complexes (1-3) with good yields. These complexes were also diagnosed with several techniques, including infrared spectroscopy, Sn119,  and proton NMR, in addition to elemental analysis of the elements. These complexes were applied to find out the antioxidative activity of tryptophan and the prepared complexes by using DDPH and CUPRAC techniques. The results of the antioxidant activity in both ways showed that the prepared complexes are more effective than tryptophan from which they are derived. Also, complex 1 showed more anti-oxidant activity than other complexes.

This study shows the efficient investigated processes of the Advanced Oxidation Process (AOP) (batch and continuous), which has been used for the degradation of the phenol in aqueous solutions by (UV/CuO nanoparticles). The effects of CuO nanoparticles' initial concentration, pH, and irradiation period were investigated in a batch system. The following ideal settings resulted in the maximum removal rate of Phenol from the stock solution (99%): In batch tests, 55 mg/L from CuO nanoparticles as a stimulant, irradiation time  120 min of and at pH 6. The effects of flow rate, number of UV lamps, and reaction time were investigated in a continuous system; the results showed that the efficiency of decomposition decreases as the flow rate of solution in the reactor increases; the maximum removal efficiency of the process (UV/CuO nanoparticles) was 90 % at 20 mL/min and 120 minutes of irradiation time. Copper oxide nanoparticles are useful in general because of their strong Phenol adsorption capability in the presence of UV, as well as the fact that they reduce the amount of Phenol in the stock solution.

Here we report efficient biomass-based Hg (II) bioadsorbent. Quercus Coccifera Shell (QCS) was recycled and modified with glutamic acid by esterification as QCS-glutamate. After the FT-IR, SEM, and BET characterizations, related optimizations like the amount of adsorbent, initial concentration, temperature, and initial pH were studied to reach optimal adsorption efficiency. Then the adsorption and kinetic studies of the produced QCS-glutamate showed that Hg (II) was successfully adsorbed on QCS-glutamate with high adsorption maxima (qmax) and followed the Lagergren pseudo-second-order reaction and Langmuir adsorption isotherm model (R2≥0.99). The maximum adsorption capacities (qmax) of QCS and QCS-glutamate were found as 35.71 and 70.42 mg/g, respectively while standard enthalpy (DHo) standard free energy (DGo) and standard entropy (DSo) were found as 34.31 kJ/mol, 87.58 kJ/mol and -178.74 j/mol K respectively. This finding suggests that a novel bioadsorbent QCS-glutamate is a cost-effective and promising bioadsorbent for the removal of Hg (II) ions from wastewater. 

 Superabsorbent polymers (SAPs) have recently been designed to meet the requirements of various applications such as agriculture. In this study, a new formaldehyde cross-linked poly (acrylate-co-acrylamide) (FCP(Ac-co-Am)) SAP was successfully synthesized using the solution polymerization and based on the co-polymerization of acrylic acid and acrylamide in the presence of potassium persulfate as an initiator and formaldehyde as a crosslinking agent. Fourier Transform InfraRed (FT-IR) and Proton Nuclear Magnetic Resonance (HNMR) spectroscopy along with ThermoGravimetric Analysis (TGA) were applied to determine the molecular structure and characterization of the synthesized SAP. The swelling properties of the (FCP(Ac-co-Am)) SAP such as free absorbency, wicking capacity, and swelling rate were evaluated, and the values of 15000 ± 650 %, 0.12 ± 0.004 g/g, and 270 ± 12 s were obtained respectively. Moreover, the impact of the synthesized SAP in the improvement of soil properties was examined using real-time- polymerase chain reaction (RT-PCR), MTT, fluorescent microscopic, and, DNA Ladder assays. The obtained results showed that the (FCP(Ac-co-Am)) SAP did not inhibit germination, beneficial soil microbes and, normal plant growth. The effects of the synthesized SAP on soil and agricultural achievements in Iran, an arid country were tested and satisfactory results were obtained.

Researchers have made remarkable achievements in natural fiber-reinforced polymer composite materials based on their superior properties over other materials for usage in engineering fields over the last four decades. Agricultural-based residues are primarily available in various countries; Nowadays, these residues are used to reinforce fiber material for preparing composites. Zea is one of the agricultural residues-based fibers. The present effort investigates the thermal property, hardness, water absorption property, and dynamic behavior of the composite material in the form of plates comprising polyester matrix reinforced with zea fibers. These properties are characterized by the composite plate possessing superior mechanical strength. The reinforcements are randomly oriented in the polyester matrix which is manufactured by compression molding technique. The experimental results showed that the composite plate exhibited superior mechanical and thermal properties. 

Sn-doped zinc oxide (ZnO:Sn) thin films were deposited onto the ultrasonically cleaned pre-heated glass substrates by employing a simplified spray pyrolysis technique using a spray gun at a constant temperature 250oC. The films were deposited on the substrate for various solution volumes by taking 0.05M of Zinc acetate as precursor concentration along with 0.0001M & 0.0003M Stannic chloride. The thickness of the films was calculated by the gravimetric weight difference method. The effects of Sn concentration on the structural and optical properties of films were investigated. The deposited films of Sn-doped ZnO showed that the films are c-axis oriented with hexagonal wurtzite structure and preserve their (002) preferential orientation. The grain sizes decreased depending on the increasing Sn concentration. From the optical spectra, all the film exhibits a better transparency of about 80% to 90% in the visible region along with a sharp absorption edge observed which is suitable for optoelectronic applications. The optical band gap slightly increases with increasing Sn doping concentration.  The electrical properties of the films show that the resistivity of the film decreases with the increase of Sn concentration with ZnO. The results suggest the potential application of Sn-doped ZnO thin film as a transparent conducting oxide layer for different optoelectronic and photovoltaic devices.

A study of the partial substitution of feldspar by Blast Furnace Slag (BFS) and its effects on the properties of sanitary ceramics, has been carried out. Characterization of rheological behavior, thermal, structural, physical, and mechanical properties of fired sanitary-ware bodies, show that 10wt. % is the optimal value for BFS in the formulation of sanitary ceramic. DRX, SEM, and FT-IR analyses confirmed that the starting crystalline phases (quartz and mullite), with the gradual appearance of anorthite, allow a non-negligible improvement in flexural strength (33 to 38 MPa), and a reduction in water absorption (0.35 to 0.10 %). From DTA/TG data, a little change in weight loss during the firing process (8.83 to 9.66 wt. %), was recorded. The Na-electrolytes with a mass ratio Na2CO3/ Na2SiO3 = 1.5, and a combined mass percentage (0.375 wt. %), are found to give the optimum values for good quality sanitary ceramic slip.

The motion of a single droplet rising in quiescent yield stress fluids was investigated experimentally. By using a high-speed camera to follow the rising droplet, the images of the recorded frames were digitized and analyzed using MATLAB, and the aspect ratio and terminal velocity of the droplets were obtained. The results show that the droplet aspect ratio decreases with the increase of dimensionless numbers such as Eötvös number and Tadaki number, and the droplet gradually changes from spherical to ellipsoidal. The larger the yield stress, the larger the Bingham number, which limits the lateral stretching of the droplet, and the droplet shows a spherical shape. The experimental drag coefficient and aspect ratio were compared with correlations in literature, and the comparison showed that these correlations do not give fully satisfactory results in predicting the drag coefficient and aspect ratio of droplet rising in yield stress fluid, showing a big relative error. Therefore, two new empirical correlations were proposed to predict the aspect ratio and the drag coefficient, respectively. It was found that the calculated results by the present correlation agree well with the experimental data.

The performance of surfactants especially in two-phase systems, depends on their type, Hydrophile-Lipophile Balance (HLB) number, concentration, and whether the surfactant is ionic or non-ionic. The current work was conducted to study the effect of the presence of Cetyltrimethylammonium Bromide (CTAB), a cationic surfactant, in air-water systems. Thus, the behavior of a single air bubble rising in aqueous CTAB solutions was studied experimentally. The independent test variables are solution concentration (0.4-1.6mM) and bubble diameter (3.5-4.6mm). The effect of these variables on rising velocity, bubble shape, and drag coefficient has been studied. Due to the importance of the drag coefficient in two-phase fluid, the effect of Reynolds number, Eötvös number, and aspect ratio on it has also been evaluated. Experiments have been performed at high Reynolds numbers (850<Re<1000), which are obtained by increasing the surfactant concentration. The results showed that the selected ionic surfactant had a more tangible effect on bubble behavior than nonionic surfactants. Moreover, there is no noticeable difference in the behavior of the bubble rising at concentrations above and below of Critical Micelle Concentration (CMC) of CTAB, which can be attributed to its high aggregation number compared to other surfactants.

 Tonka250 is a liquid fuel containing equal percentages of triethylamine and xylidine which has attracted the attention of space industries due to its favorable performance characteristics. Tonka250 has a low Ignition Delay (ID) time in the presence of AK27 as a liquid oxidizer (about 24 ms) and can be used as a starter fuel in engines working with a non-hypergolic combination of fuels and oxidizers. In recent years, due to the carcinogenic effect of Tonka250, novel fuels have been introduced to replace it with high-performance properties and non-carcinogenic effects. A combination of tetramethyl ethylene diamine (TMEDA) and dimethyl aminoethyl azide (DMAZ) can be a candidate for this purpose. According to the results obtained from the current research, the equal weight percentage of TMEDA and DMAZ has an ID time of 14 ms in reaction with AK27. The ID time was measured through the cup test method with a fuel droplet in the liquid oxidizer. The density and density specific impulse of fuel TMEDA-DMAZ are close to those for Tonka250 while the values of specific impulse for fuel TMEDA-DMAZ are about 6 seconds more favorable than Tonka250 at the chamber and exit pressures 6.8 MPa and 0.1 MPa, respectively. Therefore, it seems that fuel TMEDA-DMAZ is a good candidate for replacement for Tonka250.

A plant was developed that uses a sulfur-ammonia thermochemical water-splitting process for H2 production. Hydrogen is beneficial as a fuel in different industries and automobiles. Aspen Plus was used for the simulation of hydrogen plant modeling. This process consists of electrolytic oxidation of ammonium sulfite and the thermal breakdown of potassium pyro sulfate and SO3 in the oxygen production half cycle. The reactions are carried out by solar thermal energy. The inlet stream is water, and the product streams are H2 and O2 gas. This research focuses on scrutinizing the economic strength of hydrogen production by electrolysis. During the research, it is clear that this type of study has great potential to reduce carbon emissions. That there is concluded economic potential for the electrolytic system. The model is for the full-scale operation that will produce approximately 1.3 lac kg H2 / day. It is equal to 370MW. Design specifications were placed in strategic areas of this model to aid in its conversions. Model convergence is complex because of various material and energy recycle loops within the plant. The overall electricity needed to start the process is intramural from squandering heat. The thermal energy storage system will operate continuously without any shutdown. Three substitutes for hydrogen production from solar thermal energy have been inspected from both an efficiency and economic point of view. This observation shows that the possible alternative using solar energy with the help of thermochemical water splitting to manufacture H2 is the best one. The other methods consider the direct conversion of solar energy into electrical energy by Si cells and H2O analysis. The usage of solar energy to power a vapor cycle leads to the production of electrical energy.

This paper presents a biogas water vapor reforming system for hydrogen production. The biogas mixture contains a large percentage of methane and carbon dioxide and small amounts of other gases. Thermodynamic modeling (energy and exergy) is performed on the proposed system, and a study on the effect of various system parameters such as temperature and the molar ratio of carbon dioxide to methane in the biogas mixture on hydrogen production, energy, and exergy efficiency of the whole system has been done in this paper. The results show that the increase in steam reforming reactors in a constant molar ratio of carbon dioxide to methane in the biogas mixture increases hydrogen production and the energy and exergy efficiency of the system. However, increasing the molar ratio of carbon dioxide to methane in the biogas mixture at high temperatures reduces hydrogen production per mole of methane. As a result, the energy and exergy efficiency of the whole system is reduced. Also, the highest energy and exergy efficiency of the entire system in the conditions where the amount of hydrogen production is maximum is 52% and 42%, respectively. 

As climate change becomes a more severe problem each day, the need to respond to it firmly grows in importance. For decades many scientists believed fusion, or, as it is called in the engineering society, the artificial sun was the future of unlimited clean and cheap energy sources. Since 2007 when the international nuclear fusion research and engineering megaproject started as a mega cooperation project between several industrial countries, this ambition seemed to be at hand more than at any other time. This mega project was a turning point for the fusion sub-projects to emerge in many countries and regions. But as fusion projects grow in number, similar to all other energy systems, a need to analyze using the second law of thermodynamics becomes a great matter of importance. This paper aims to study the European demonstration fusion power reactor pulse integrated power plant and its waste heat recovery potential to produce hydrogen, considering the primary heat transfer system, the intermediate Heat Transfer System, including the Energy Storage System’s first option to ensure power continuity. This study shows that the fusion power plant is among the most efficient stand-alone energy systems with an overall efficiency of (85.07 and 89.1% in energy storage and auxiliary heater arrangements, respectively). Using waste heat assessments to produce hydrogen resulted in even more efficient plants and an increase of the plant’s overall efficiency to more than 94.15 and 92.05% in energy storage and auxiliary heater arrangements, respectively, close to the Carnot efficiency of a similar ideal plant, and means that the irreversibility is in its minimum state.

This study attempts to interpret the physical mechanism of temperature affecting the emission of VOCs from building materials from the viewpoint of thermodynamics. VOCs adsorbed onto building materials are assumed to form a condensed thermodynamic system. The kinetic energy of VOCs molecules takes values from zero to infinite. It is assumed that only VOCs molecules with a kinetic energy greater than the critical value can escape from building materials. Based on the Maxwell velocity distribution function, the correlation between the initial concentration of VOCs within building materials and temperature is derived. By use of the Laplace transform technique and the theorem of the initial value, the correlation between the initial emission factor and temperature is further presented on the basis of the diffusion mechanism. The present thermodynamic model was validated through experimental data in the literature. A good agreement between the present thermodynamic model and experimental data is obtained. The present thermodynamic model can also explain the effect of temperature on the emission of other gases from materials.

Multi Effect Evaporator (MEE) is an important unit operation in industrial waste effluent treatment where water recovered from MEE can be reused for industrial operations thus reducing fresh water demand of the industry leading to Zero Liquid Discharge (ZLD) and environmental sustainability. Economically, multi-effect evaporators in many industries are used to improve the steam economy and cut down the waste handling cost.  In this study, a dynamic mathematical model for a seven-effect evaporator has been developed and the model is validated against the real-time data collected from an industrial evaporator available in the Common Effluent Treatment Plant (CETP) located at Pallavaram, Chennai, India. Parametric sensitivity analysis is carried out to study the effect of various input parameters on the concentration of the output stream. Parametric studies reveal that input parameters namely heat transfer coefficient and steam flow rate have more influence on the concentration of the output.  Lyapunov-based MPC (LMPC) scheme is implemented to achieve important performance characteristics like a low salt concentration in the water discharge, disturbance rejection, and stability.  The disturbance rejection efficiency of LMPC is tested by adding 1% positive disturbance in feed concentration. Also, stability is assessed by introducing an additional delay of 2 seconds in the process. The performance of LMPC is compared with other controllers like IMC-PID and MPC. The closed-loop performance of all the proposed controllers for MEE is evaluated using error criteria and settling time. In LMPC,  ISE, IAE value,, and settling time are drastically reduced by 68.15%, 88.39%, and 21.79% respectively with respect to MPC. Thus better setpoint tracking, quicker settling time and better stabilization of product concentration will pave the way for ZLD and improved water quality of the recycled water.

This paper presents a systematic procedure to obtain the decentralized and centralized PID controller settings for a non-square stable Multi-Input and Multi-Output (MIMO) system using a simultaneous relay autotuning method with the incorporation of higher-order harmonics. In general, the assumption of filtering the higher-order harmonics will be acceptable when the system has the characteristics of a low-pass filter. However, higher-order harmonics have an impact on the controller parameter evaluation and it needs attention. Therefore, this research addresses the control of non-square stable MIMO systems in their original non-square form instead of squaring them by adding or deleting variables, and also the significance of higher-order harmonics in non-square stable MIMO systems is considered. To enhance the controller performance, higher-order harmonics are taken into consideration by observing the initial dynamics of the relay response. The decentralized and centralized control systems' performances are explored by simulation on two different 3 inputs and 2 outputs models with different levels of interactions. For these models, simulation studies were carried out for both servo and regulatory operations. The performance of the centralized control system is improved for systems with interaction (relative gain is more than 1) by 18-41% for servo operation and 14-31% for regulatory operation. Also, the performance is improved for decentralized controllers for systems with a relative gain of less than one. The time integral analysis comparison between centralized and decentralized control schemes with the incorporation of higher-order harmonics using the simultaneous relay autotuning method is implemented. The effectiveness and performance of the proposed scheme are also analyzed even in the presence of robustness and the effect of measurement noise.

In this study, the extraction of phycobiliprotein pigments from Spirulina Platensis dried powder was optimized using ultrasound-assisted extraction (ultrasonic water bath) combined with the freezing-thawing method. Response surface methodology (RSM) using Central Composite Designs (CCD) was employed to investigate the combined effect of two process variables of ultrasound time (30-90 min) and freezing-thawing time (5-12 h) on the amount of allophycocyanin (A-PC), C-phycocyanin (C-PC), phycoerythrin (PE), C-PC purity (EP), and the yield of C-PC. The purification of C-PC extracted from optimal and control conditions (extracted via freeze-thawing method without ultrasound) was performed, and the C-PC powder was evaluated by FT-IR spectroscopy and XRD. Results showed that at the optimal conditions of sonication time (55.5 min) and freezing time (5h), the average values of PE, A-PC, C-PC concentration, C-PC purity, and C-PC yield were (0.095±0.009), (0.051mg/g), (0.109±0.051mg/g), (0.498±0.25), and (2.32±0.21 %), respectively. The comparison of scanning electron microscopy images of algae biomass indicated that freezing alone and for a long time had caused more destruction of cells. The damage caused by ice crystals and large pores led to the production of extract with low purity. The ultrasonic pretreatment (5.5 min) for extracting the C-PC pigment from Spirulina Platensis compared to the control sample (12 h freezing without ultrasound) did not destroy the functional groups in the pigments.

Apple juice can be clarified by ultrafiltration; however, fouling is a limiting factor against the industrialization of the process. A scraped-surface membrane unit was designed and constructed to reduce fouling during membrane clarification of apple juice using a polyether sulfone membrane with a pore size of 4 kDa. The effects of blade rotation speed (0, 600, 1400, and 2200 rpm), transmembrane pressure (0.5, 1, and 1.5 bar), feed flow rate (10, 15, and 20 mL/s), and distance between the blade and the membrane surface (2 and 5 mm) were evaluated on the permeate flux. The results revealed that increasing the blade rotation speed up to 600 rpm would increase the permeate flux, but further elevation of rotation did not affect the permeate flux. The optimized operating condition was obtained at low transmembrane pressure, feed flow rate, and short distance between the blade edge and the membrane surface. The study of the physicochemical properties of apple juice during clarification indicated that the designed system could reduce the turbidity of the juice by more than 99%. Other properties also changed to almost the same extent as in non-rotating systems.

Soybean is one of the oilseed plants, among the most important products with high nutritional and economic value. The present research was realized by using 5 soybean varieties (Arısoy, Ataem, Derby, Safir, S-312) that were sown 2 different dates (1st – 15th July) as a second crop for 2 years (2017-2018) with 3 replications. Following ranges of fatty acid values were determined; palmitic (10.42-11.20%), stearic (4.55-5.08%), oleic* (23.62-25.16%), linoleic (51.87-53.36%), linolenic* (5.62-6.25%), arachidic* (0.77-0.96%), total* (99.22-99.66%), SFA (15.94-16.81%), MFA* (23.63-25.17%), PFA (52.68-54.22%), total UFA (77.51-78.26%), w-6/w-3* (8.41-9.05%) while changes in the fatty acids were statistically significant that were affected by sowing time (linolenic and w-6/w-3), variety (arachidic, total) and interactive (oleic, arachidic, MFA) effects. It was concluded that Arısoy and Ataem varieties can be used in breeding studies focusing on oil quality while late sowing caused to decrease in total UFA. As a result, it was concluded that the fatty acid composition quality could be changed depending on the sowing time for oil quality. In addition, it was revealed that ecology, planting time, and cultivar had significant effects on fatty acid composition. The lipid profile in soybeans can be evaluated to improve human health with appropriate variety selection and sowing time. Furthermore, these varieties which can be grown successfully as a second crop, show a wide variation in fatty acid quality and can be used in breeding studies.

Recently the demand for dietary fiber-enriched foods has increased due to consumers' interest in the nutritional and health benefits of functional foods. Date Seed Powder (DSP) is rich in dietary fiber and other nutrients such as minerals, antioxidants, unsaturated fatty acids, amino acids, and tocopherols. It is applicable as a cheap and valuable source to produce functional foods. In this study, DSP was added to the cupcake formulation at 5 levels (0.0, 2.5, 5.0, 7.5, and 10.0%), and the effect of this substitution on the physical, chemical, microbial, and sensory properties of the final product was investigated during 28 days of storage at 4 °C. Based on the results, adding DSP to the cake formula significantly increased the amount of fat and fiber of the cake. Substituting wheat flour with DSP increased the total phenolic compounds and moisture content of enriched cakes compared to the control. Furthermore, the peroxide, para-anisidine, and stiffness of fortified cakes were more than the control at all storage times. Adding DSP to the cake reduced the specific volume, L* and b* of crust and crumb. The highest overall acceptance of fortified cakes with DSP was 2.5% DSP. According to the response surface models, the optimal quality of cakes was observed at the DSP ratio of 3.6 % and 0 days after preparation. Results demonstrated that DSP could be used as a dietary fiber supplement for cake enrichment.

The CO2 Compression and Purification Unit (CPU) is an auto refrigeration system that works based on the Joule-Thomson effect, which requires high energy for compression and refrigeration. Therefore, optimization of this system has been an attractive research field in recent years. However, this system is applied for capturing CO2 from Oxy-Fuel Combustion (OFC) flue gases. The OFC refers to fuel combustion with approximate pure oxygen which in practice is usually produced from a cryogenic air separation unit (ASU). In this study, CO2CPU system was redesigned based on oxygen stream effluent from cryogenic ASU. The results obtained by analyzing a sample of combustion gas showed that only the oxygen gas stream produced in the ASU unit, which is being prepared to enter the combustion chamber is sufficient to condense and refrigerate the CO2CPU system. The performance of the proposed design was compared with three recently proposed schemes for a given feed. The results showed that the proposed system can perform at lower operating pressure and needs a significantly smaller heat-transfer area. In addition, the integration of CPU and ASU decreased the number of compressors and reduced the heat exchange area of cold boxes by at least 79% and the compressor energy consumption by at least 29%. It also allowed the delivery of the final CO2 product in the subcooled liquid phase. Therefore, instead of the expensive compressor, the pump can be used to increase the pressure to transfer CO2. Furthermore, optimization and sensitivity analysis were performed on this system using the Response Surface Methodology (RSM), which indicated that the inlet pressure and the temperature of the second separator had the most significant effect on this system.

Salmonella is among the most common foodborne pathogens that affect millions of people annually, sometimes with severe and fatal outcomes. In recent years, significant efforts have been made to develop natural antibacterial compounds, such as essential oils. Based on GC/MS analysis, Pulegone (33.10 %), Carvacrol (10.60 %), Piperitenone (9.33 %), Eucalyptol (8.01 %), -Terpineol (5.46 %) and L-Menthone (4.79 %) were the major components of phytochemicals of Ziziphora clinopodioides essential oil (ZEO). Encapsulation of ZEO using maltodextrin and gum arabic as wall in ratio of 1:1 with ZEO concentrations of 30 % (w/w) and 2.5 % (w/w) was done by spray drying method. The research results showed that, if the concentration of essential oil increased, the antimicrobial properties increased. The microbial population in the encapsulated ZEO treatment was lower than in the free ZEO treatment. The lowest inhibitory effect of ZEO was related to the concentration of 0.25 % (w/w) in the free state. The highest inhibitory effect of ZEO was related to the concentration of 1% (w/w) in the encapsulated state. The bacterial inhibitory property at the concentration of 0.5 % ZEO (w/w) in the free state was approximately equal to the concentration of 0.25 % ZEO (w/w) in the encapsulated state. The inhibitory properties of bacteria at concentration of 1 % (w/w) in the free state was better than the concentrations of 0.25 and 0.5 % (w/w) in the encapsulated state. Based on the results, formulation of ZEO in minced beef can prolong its shelf life and control microbial changes during storage at 4 oC. ZEO is insoluble in water, but a water-soluble microcapsule can be produced using this method. ZEO can be used as a natural and effective preservative for reducing pathogenic bacteria and increasing the shelf life of food.

With the expansion of commercial centers such as hotels, restaurants, markets, etc., the amount of waste generated by these institutions has become an important challenge in large cities. On the other hand, the application of new biotechnologies to convert biodegradable waste into valuable materials such as biogas and other biofuels is increasing dramatically. The aim of this study was to investigate the potential of biogas production from a mixture of cow dung and restaurant wastes using an anaerobic bioreactor. Operational parameters such as pH, Carbon to Nitrogen ratio (C/N), mixing ratio of restaurant and cow wastes in weight percentage (0:100, 50:50, 70:30, and 100:0), total solids (TS) (%5, %10, and %20), temperatures (35, 45 and 55 °C) and Oxidation-Reduction Potential (ORP) were evaluated. The results showed that the maximum yield and percent of the biogas produced from cow manure digestion separately was 1003 mL/day and %52.82. Digestion of the mixing of restaurant and cow wastes showed the best mixing ratio, total solid and temperature were 70:30 (w/w), %20 and 55°C respectively, and biogas production yield and percent was obtained 5430 mL/day and %74.4 respectively. The ORP obtained in this study was -327 millivolt (mv), which indicates the appropriate conditions of the anaerobic process in biogas production and confirmation of methanogenesis.

Corrosion is a spontaneous process that affects valuable metal products, is dangerous, and causes expensive damage to many industries. There are many kinds of corrosion; among them is microbial corrosion. The effect of Microbiologically Induced Corrosion (MIC) can be explained in three steps: development of biofilm, alterations of the environment of the metal surface, and metal degradation (or corrosion). Common bacteria responsible for inducing MIC are sulfate-reducing bacteria, iron-reducing bacteria, and acid-producing bacteria. Metals and alloys have been treated with corrosion inhibitors to prevent microbiological corrosion. Expensiveness, toxicity, and in certain instances, ineffectiveness of these inorganic inhibitors have shifted the attention towards the organic green inhibitors. These green inhibitors used against corrosion are derived from plant extracts and organic substances. In addition to being ecologically acceptable and environmentally friendly, plant extracts are readily available, inexpensive, and renewable. This review paper explains microbial corrosion in metals and the mechanisms of MIC. In addition, this paper also reviews metal corrosion inhibition, green inhibitors, their types, and the impact of molecular structures on corrosion inhibition.