Iranian Journal of Chemistry and Chemical Engineering
Volume:42 Issue: 6, Jun 2023

The non-toxic BSA-based NanoParticles (NPs) are developed without any additives with hydrothermal SubCritical Water Treatment (SCWT). The optimum BSA-based NPs are gained by applying Response Surface Methodology (RSM) based on particle size, zeta potential, and polydispersity. The SCWT conditions are optimized in terms of these three dependent variables, which have significant impacts on the BSA-based NPs application. The optimum BSA-based NPs prepared with 2.73% (w/v) of initial BSA solution concentration, the lowest initial concentration that is used to synthesize BSA-based NPs by now. The SCWT condition of 173 °C and 2.07 min of SCWT holding time shows that the zeta potential of -38.87 mV with the finest particle size and PI (147.32 nm and 0.24, respectively) is the optimized composition. The fabricated BSA-based NPs are characterized by the UV-vis, screening electron microscope (SEM), and stability assessment study.

In this study, a series of LaCoO3 perovskite catalysts with varying calcination temperatures were synthesized hydrothermally, and their structure, morphology, and optical properties were investigated using X-Ray powder Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray electron spectroscopy analysis (XPS), Magnetic Property Measurement System (MPMS), and other characterization techniques. Using phenol as the target degradation product, the photocatalytic degradation reaction was carried out in the presence of visible light. In addition, the photocatalytic mechanism of LaCoO3 perovskite was also discussed. The experimental results showed that the LaCoO3 perovskite catalyst has been prepared with good crystallization. The particle size of the catalysts ranged from 10 to 40 nm, and the specific surface area decreased with calcination depth. Moreover, all the LaCoO3 catalysts showed strong paramagnetism, and the particles were regularly agglomerated under the action of magnetic force. LaCoO3 catalyst (the calcination temperature of 750 °C) exhibited high photocatalytic activity. In addition, the study of photocatalytic mechanisms revealed three degradation pathways for degrading phenol into inorganic small molecules such as CO2 and H2O via highly active HO•, HO2•, and h+ radicals.

In the present work, a polyacrylamide-pumice stone (PAAm-PMC) composite has been synthesized and used as an adsorbent for the fast removal of copper ions from wastewater. The PAAm-PMC composite was synthesized by the conventional free radical polymerization method and characterization has been done by Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscope (SEM). Effects of various parameters on the adsorption capacity of the synthesized PAAm-PMC composite were studied and optimized. The optimized values of various parameters found were: contact time (60 minutes), pH value of solution (6.5), composite dose (0.05 g), Cu(II) concentration (1500 mg/L), and temperature (323 K). The kinetic studies reveal that the rate of adsorption of copper on the composite, increases with time and the maximum adsorption achieved for copper ions is ~ 96 %. The fast adsorption kinetics followed pseudo-second-order kinetics when modified composites were used. Among three different isotherm models, Langmuir adsorption isotherm model has been found to be the best-correlated model with experimental data based on a higher correlation coefficient with a maximum Langmuir loading of 500 mg/g. The positive entropy during the adsorption process for both the materials (ΔS0= (55.6855 J/(mol.K) for PAAm and 151.0737 J/(mol.K) for PAAm-PMC at 303K) suggests, that the adsorption process is thermodynamically favorable and increases with the increase in temperature. Gibbs free energy values are found to be higher for composite material suggesting higher equilibrium constant values (ΔG0 = -5.0191 kJ/mol for PAAm vs -8.0059 KJ/mol PAAm-PMC at 303K). Structural strength and stability of the synthesized composite can be accessed, as modified composites were used up to three times for the adsorption removal of Cu(II) ions from waste-water, after regeneration. These investigations confirmed that the synthesized PAAm-PMC composite can work as an effective adsorbent for the economical and fast removal of Cu(II) ions from wastewater.

In the present study, the adsorption capacities of two intercalated smectites, Na+-PMt and Ca2+-PMt with the Zr pillar were investigated on fluorescent dye adsorption. The modified clay sample was characterized in detail using X-Ray Diffraction (XRD), and Fourier Transform InfraRed spectroscopy (FT-IR). The values of interlayer spacing are similar about 16 Å for all samples. The adsorption isotherms fit well with the non-linear Langmuir isotherm model and the maximum adsorption capacities of all materials are determined. For all samples interlayer spacing after interactions between the dye and the modified clay are similar about 18 Å as measured by X-ray diffraction. The pillar improves the adoption capacity to wards fluorescein due to its location inside interlayer space. Interestingly, the time-resolved fluorescence shows that the dye is not released in solution as is the case for the pristine clay.

The present study evaluates the performance of the lignocellulosic fibers Momordica Charantia for the sequestration of lead (II), zinc (II), chromium (VI), and copper (II) ions from a liquid medium. The biomass has been analyzed and depicted by Fourier-transform infrared spectroscopy and scanning electron microscope. The biosorption rate of these toxic metals depended on contact time and pH solution. The maximum biosorption rate was found at pH = 6.0 for the biosorption of divalent metals and for hexavalent chromium the maximum rate was obtained at pH =2.0. At optimal conditions, the experiment results elucidate that metal uptakes are rapid systems at 60 min equilibrium time, and the order of uptake metal ions is lead > Chromium >Zinc> Copper. The adsorption isotherms were studied and modeled using Langmuir, Freundlich, and Temkin equations. The Langmuir isotherm model presents goodness fit for all metals studied by height coefficient of coloration, with a maximum capacity of 8.9, 5.9, 4.67, and 3.9 mg/g for lead (II), chromium (VI), Zinc (II), and Copper (II), respectively. Kinetic modeling elucidates that the biosorption processes followed better the pseudo-second-order model. Furthermore, the thermodynamic factors demonstrated that the biosorption behavior of heavy metals was favorable, spontaneous, and exothermic processes. Finally, this study showed that the M. Charantia threads could be considered an excellent biomaterial to be employed as an effective sorbent for removing heavy metals in the liquid environment.

This research investigates the electrode-based dielectrophoretic (eDEP) separation of live and dead yeast cells with diameters of 6 and 5 μm using COMSOL Multiphysics 5.6 software. Five electrodes are placed on one side of a rectangular microchannel with three inlets and three outlets. A non-uniform electric field is created inside the microchannel by applying an alternating electric field (AC) to the electrodes. Microchannel inlets include an inlet for injecting a sample fluid consisting of deionized water containing two species of live and dead yeast cells and two inlets for injecting deionized water as a sheath flow to concentrate the cells before reaching the area affected by the electric field. The study is conducted in two dimensions and the effect of various factors, including the electrical voltage applied to the electrodes, the frequency (f), the length of the electrodes, their distance from each other, and the inlet velocity on the efficiency and purity of cell separation is examined. In addition, the optimal conditions for achieving complete separation of live and dead yeast cells utilizing the proposed microfluidic device are presented as follows:  = 60 μm/s,  = 360 μm/s,  = ±4.35 V, and f = 3.18 MHz.

Determination of organophosphorus pesticide diazinon (DZ) in water was described based on localized surface plasmon resonance of citrate-capped silver nanoparticles (CC-Ag NPs) in this study. The surface plasmon resonance band was scanned by UV–visible spectrophotometer and Transmission Electron Microscopy (TEM) was employed to reveal the interaction, surface characteristics, and particle size. With adding DZ to the CC-Ag NPs, it was adsorbed onto silver nano-spheres in an aqueous solution and the color of the silver nanoparticles changed from light yellow to orange or brown depending on DZ concentration. As a result of aggregation, the absorption peak of silver nanoparticles around 393 nm decreased and a new peak appeared in 520 nm. The wavelength and intensity shifts were characteristic of the pesticide structure and concentration, respectively. The interaction between the sensor and the pesticide was a result of the soft metal surface binding to the soft sulfur atom of the pesticide. Under optimized conditions, a linear relationship between DZ concentration and the absorbance ratio of A520/A393 and the limit of detection was found in the range of 2- 80 µM and 0.12 µM, respectively. The present method has good repeatability reproducibility and good stability. The proposed method was used for real water samples and the results are in good agreement with other methods of analysis.

Herein, we reported an Activated Glassy Carbon Electrode (AGCE) for the detection of L-tryptophan (Trp). AGCE was made by successive cyclic voltammetric potential scanning of glassy carbon electrode (GCE) from -1.5 V to 2.5 V in 0.1 M pH 7.0 phosphate buffer as a supporting electrolyte. The surface morphology of AGCE and Un-Activated Glassy Carbon Electrode (UGCE) was characterized by a Scanning Electron Microscope (SEM). The voltammetric sensing of Trp is carried out using Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV). The electrochemical properties of the AGCE and UGCE were also examined by CV and Electrochemical Impedance Spectroscopy (EIS). AGCE exhibited enhanced anodic peak current and less overpotential for the oxidation of Trp than UGCE. LSV was used for the quantitative determination of Trp. Two linear ranges were obtained for the determination of Trp using LSV from 2.5 μM – 20.0 μM and 2.0 μM – 100.0 μM. The limit of detection (3σ/m) was 0.098 μM.  The current method was successfully used to detect Trp in urine and healthy human serum.

Determining the band edges of Quantum Dots (QDs) in electrolytes with different redox is still a serious challenge for many researchers. A new and innovative method to trace Valence Band (VB) and Conduction Band (CB) edges is Electron Exchange Magnitude (EEM) determination with logarithmic scaling in Cyclic Voltammetry (CV) curves. The EEM method is an adaptation of the Tafel method, which determines the equilibrium currents in the logarithmic scale in the potential current curves. Accordingly, the equilibrium currents on the surface of QDs can be related to the currents occurring at the band edges. Since the band gap varies with the size of the QDs, the shift of the band edges occurs as the size of the QDs changes. In this study, PbS QDs were deposited on ITO/ZnO by the SILAR method and considered as a photoanod. The band edges were investigated by EEM method in electrolytes with and without Sulfide polysulfide redox. In this way, the minimum value of EEM in the anodic and cathodic range was considered as the VB and CB edges, respectively. Investigations show that some results of this research are in good agreement with the observations and results of others in matters such as determining the PbS QDs bandgap, although there are significant differences in determining the exact position of the band edges.

Hybrid MMCs are a new class of materials that exhibit superior characteristics and functional response when compared to monolithic alloys and mono-reinforced MMCs, and thus have tremendous potential for widespread application in modern industrial and engineering applications. Since the manufacturing fraternity is proliferating, a cyclic evaluation of understanding the behavior of hybrid MMCs and their evolution is needed. Therefore, to address this necessity, this paper presents a detailed review of hybrid MMC manufacturing methods, materials (matrix and reinforcement) used, physicomechanical, tribological, and corrosion properties, and challenges associated with hybrid MMCs. This retrospective investigation presents the state of the art of hybrid MMC materials in the categories involving matrix materials and their alloys, ceramics reinforcements and secondary reinforcements, and the applications and formation of microstructures. This paper also discussed the overview and the status of various matrix and reinforcement materials in manufacturing hybrid MMCs using different fabrication methods. Further, the significant challenges associated with the fabrication of hybrid MMCs using different manufacturing methods, such as distribution of reinforcement, wettability, and other common limitations identified in the literature, are presented. This paper provides a broad-spectrum attitude on hybrid MMCs techniques, challenges, and future research directions.

Modern aircraft engine components with thin-walled structures and complex shapes pose enough difficulties in the processing of materials which compel the aerospace industry to adopt the use of layered Additive Manufacturing (AM) technology. The aerospace industry is looking toward more durable, smaller, and lightweight components. However, AM technology suffers certain obstacles in the mass production of aircraft components due to critical issues such as part anisotropy, poor mechanical properties, and inadequate surface quality. Therefore, various surface modification and post-processing methods have been proposed to improve the surface characteristics of AM-manufactured parts. In this review, we have overviewed the historical developments, various post-fabrication methods, and applications concerning different metal AM processes. Several kinds of AM and their comparison for aerospace applications, their post-processing technologies, and their integration with AM processes are discussed in this review towards the possibility of future advancement in this field.

An experimental investigation of Sanitary Ceramic Waste (SCW) for use as raw material in the manufacture of vitreous china bodies is presented. The gradual substitution of feldspar by sanitary ceramic waste and its effects on the technical and physical properties of sanitary bodies have been studied. The rheological behavior of sanitary slip is improved using Na-electrolyte. The characterization of the fired vitreous bodies at 1230 ◦C shows that 10 wt. % SCW substitution is the ideal value for the composition of a vitreous china body.  FTIR and DRX analyses confirmed that the crystalline phases (quartz and mullite) are stable during the addition of sanitary ceramic waste with a significant increase in their intensities. SEM micrographs show an increase in the porosity when the addition of sanitary ceramic waste exceeds 10wt. %, as a result of the reduction of the vitrified phase. From physical-mechanical characterization, an improvement in flexural strength (33 to 41MPa), and a reduction in water absorption (0.36 to 0.31 %) were recorded. These positive results open very promising prospects for the valorization of sanitary ceramic waste, with many technical, economic, and environmental benefits.

Minimizing the environmental impact and optimizing the performance of the cement manufactured is the magic formula sought to define the glorious trio of performance, cost, and environmental impact. The use of industrial by-products such as phosphogypsum can help to achieve the sustainability of the cement industry. An industrial cement series was used to investigate the effect of low phosphogypsum content on Portland cement reactivity with percentages ranging from 1 to 4%. The raw materials, clinker, gypsum, and phosphogypsum, were characterized by X-ray fluorescence, and the clinker mineralogy was determined by X-ray powder diffraction coupled with the Rietveld method analysis. The reactivity of cement was followed by isothermal calorimetry, compressive strength, conductivity measurement, and thermal analysis. The results revealed that there is an influence of phosphogypsum in this range of composition on the early cement reactivity. However, it may enhance the long-term cement reactivity and the concrete performance. It has been found that the isothermal microcalorimetry analysis method, is able to detect the formation of an exothermic component due to the precipitation of phosphorus in the form of apatite even at very low phosphogypsum integration rates.

In this research, a numerical study was conducted to analyze a novel design for overcoming the detrimental effect of high‑temperature operating conditions on the separation efficiency of a square-based cyclone. This kind of cyclone can be utilized in the Circulating Fluidized Bed (CFB) boiler and it was shown to become one of the most appropriate cleaning tools for high-temperature gases. Previous studies found that the separation efficiency of a cyclone reduced remarkably with the increment of inlet temperature resulting in weaker swirling flow over cyclones at extremely high temperatures. Hence, it is vital to develop an effective approach to prevent this detrimental impact. The novel cyclone design is based on the idea of altering the inlet shape on the flow field and enhancing the cyclone collecting efficiency in high‑temperature operating conditions. Three separate inlet configurations, namely flat, oblique, and curved inlets were particularly developed and investigated numerically through the Computational Fluid Dynamics (CFD) method to maximize the low separation efficiency of a square cyclone influenced by the high‑temperature operating condition. For simulating the flow of particles, the Eulerian-Lagrangian methodology is implemented for solving Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. The Discrete Random Walk (DRW) is utilized for modeling fluctuations of velocity. Numerical results indicated that using oblique and curved inlets generated a raising in pressure drop but they significantly improved the separation efficiency of the cyclone separator. Among all inlet shapes, oblique inlet dramatically enhanced the separation efficiency by up to 15% at an inlet velocity of 12 m/s.

In this work, the impact of Ionic Liquid (IL) pretreatment of Spent Coffee Grounds (SCG)  is assessed using three analytical techniques. Four different classes of ILs were employed to compare the effect of cations and anions. Thermogravimetric analysis under the N2 environment was done to collect analytical data at 20 °C/min. Reactivity analysis evaluated mean relative reactivity (Rm) and pyrolysis factor (PF), kinetic analysis determined activation energy (Ea) and pre-exponential factor (A), while thermodynamic analysis helped to find enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS). IL treatment aided thermal breakdown by increasing the mass loss % from 93% for untreated SCG to 97% after IL treatment. The decomposition rate for the IL-treated samples was calculated to be in the range of 6.7-7% min-1. All the ILs increased Rm, with the largest increase from 2.42*102 to 2.57*102 % min-1°C-1; they also decreased the Ea of SCG from 42.25 to as low as 29.91 kJ/mole. This might be induced by the breakdown of the lignin structure of SCG by IL treatment leaving it sensitive to heat treatment. IL-treated SCG ΔS values indicate increased disorder and thermal instability. Among the studied ILs, relatively inexpensive and infrequently used [P66614] [Cl] and [N1444] [Cl] fared better than imidazolium-based ILs. This study could provide useful knowledge in finding effective cations for designing task-specific ILs for the thermochemical conversion process.

An ebulliometer designed with automated feeding was tested and verified in this work. The ebulliometer is made of stainless steel. The feeding of the substances is automatically controlled with a computer. In the equipment, both the liquid and vapor phases are recirculated.  The binary mixtures isobutyl acetate + 1–propanol and isobutyl acetate + 2–propanol were studied and the vapor–liquid equilibrium of these mixtures was determined at 101 kPa. The isobaric T–x–y data are reported, including the azeotropic point of the isobutyl acetate + 1–propanol binary system. The calculations have been carried out considering the non–ideal vapor phase and the activity coefficients of the liquid phase have been obtained. The thermodynamic consistency of the system was verified with the Van Ness point–to–point test. The f–f approach was used to evaluate the data reproducibility by considering the Perturbed Chain–Statistical Associating Fluid Theory (PC–SAFT).

In an impinging air jet, nozzle shape noticeably impacts heat transfer between jet and plate by affecting the velocity profile at the jet exit and thereby potentially modifying the behavior of the air jet vortex structures. This study analyzed the influence of four different injections (0 to 80 mm). They all possess the same free area and the equivalent diameter is D = 9 mm. Experiments have been conducted for Reynolds numbers 192.61< Re<1661.26, for orifice-to-plate distances 0.67 < H/D< 16, and for the temperature of the jet was conducted 115oC. In this effect which is greater in the round shaped orifice was taken. The velocity profile at the jet exit (6.4 and 9.2 m/s), for a distance from the point of impingement (x/D = 0 to 160) presents a shape for the round orifice (0.5 to 3 mm). Thermal results also show that a round orifice on higher heat transfer rate for injections. The measurements of parameters on the behavior of local heat transfer characteristic values on the impingement surface and the effect of the velocity values were discussed. From the results, it was observed that the peak of the heat transfer obtained at the impinging point higher jet velocity of 9.4m/s.

Semi-circular cylinders provide better space economy than circular and other non-circular cylinders. The cylinders are frequently used in a tandem arrangement in heat transfer equipment. The present study aims to obtain the flow and heat transfer characteristics for the tandem arrangement of semi-circular cylinders. The cylinders are placed in a vertical channel with a blockage (β) of 0.2. The upward flow under the reverse gravity is considered here. The influence of various parameters such as Reynolds number (Re), Prandtl number (Pr), Richardson number (Ri), and spacing between cylinders (YC) is observed. The governing parameters are varied in a range of 1 ≤ YC ≤ 6, 1 ≤ Re ≤ 50, 0.7 ≤ Pr ≤ 50, and 0 ≤ Ri ≤ 2. The numerical results are obtained by solving governing equations using FVM (Finite volume method). The velocity field, thermal field, drag coefficient (CD), pressure coefficient (Cp), and average Nusselt number (Nuavg) are presented. The increase in Re and Pr has enhanced the Nuavg and CD, whereas Ri and YC have shown complex dependency. The obtained results show that the mutual interaction of upstream and downstream cylinders has vanished for YC > 4. The upstream and downstream cylinders have shown different behavior at identical operating conditions. The drag coefficient for the upstream cylinder varies with YC for 1 ≤ Re ≤ 10, whereas for 10 ≤ Re ≤ 50, it shows negligible change except for the case of Pr = 0.7 and Ri = 2. The drag on the downstream cylinder increases monotonically with an increase in YC. The average Nusselt number for both cylinders increased with an increase in YC except for the downstream cylinder at Re = 1 and Pr = 0.7. Overall, the complex interplay of governing parameters has been observed in the flow and thermal characteristics.

The water level control in boiler drums is a crucial process in many process industries. In industries, water spillage or overheated tubes of the water boiler are the serious consequences of extremely high or low-level drum water level maintenance. The boiler drum is a MIMO system, consists of dead time nonlinearity and thereby there exists a transportation lag between the input and the system. Also, they possess high dynamic variations. Hence, the control of the boiler drum level is of great importance. Though, conventional PID controllers are employed in industries, due to the presence of nonlinearity, boiler drum performance can be affected when it is controlled by a PID controller. Moreover, the PID controller produces a larger settling time. Here, a robust controller for the boiler drum level control based on the H-infinity technique is designed. The first-principle mathematical model of the boiler drum is formulated. The uncertainties namely: structured uncertainty, unstructured uncertainty, and nonlinear uncertainty are modeled by incorporating the boiler drum dynamics including its inherent nonlinearity. The boiler drum level control is carried out using the H-infinity controller scheme with the uncertainties accounted for and the performance is compared with that of a conventional PID controller. The qualitative and quantitative comparison of performances of the above control schemes reveals that the H-infinity controller has a quick rise time and faster settling time.

With the advancement of technology, food packaging has gradually changed to make changes for the consumer's convenience. Self-heating packages allow customers to heat drinks by using exothermic reactions. In this study, a cylinder made of 316L stainless steel was used to heat 200 mL tea and 200 mL low-fat pasteurized milk using silicon dioxide and aluminum reactions. For this purpose, after pouring the reactive material and closing the cylinder lid, the heating process began by placing it inside the beverage. As a result, the temperature inside the cylinder after 82 s (1 minute and 22 s) increased from 28.1 °C to 122.6 °C and this amount of heat led to an increase in the temperature of the tea from 26.3 °C to 40.9 °C in 277 s (4 min and 37 s). Also, after 563 s (9 min and 23 s), the milk temperature increased from 24.8 °C to 38.1 °C. Then, the heating of the cylinder containing this reaction inside the mentioned beverages was simulated and modeled using COMSOL Multiphysics software. It has been determined that the experimental data and simulated models were properly fitted.

Microalgae are used for various purposes, mainly as food supplements by people because of the protein, carbohydrate, fatty acids, vitamins, minerals, pigments, and many other compounds they contain. Efforts to utilize microalgae as a raw material for the production of biodiesel are increasing, especially in European countries. In this study, the effects of different light sources (Led, Incandescent, Green, Yellow, Blue, Red)  and cycles 10:14,12:12,14:10,0:24(night: day) on the growth and lipid production of Chlorella protothecoides and Chlorella  ESP-6 species were investigated. All of the experiments were conducted in 100ml flasks that contained culture medium BG 11.  The results showed that Chlorella ESP-6 reached 0.25 gdw/L maximum cell concentration under the incandescent lamp (3.16 Klux), whereas 0.39 gdw/L maximum cell concentration under the 14:10 light cycle. Chlorella protothecoides attained a maximum cell concentration of 0.18 gdw/L, and 0.26 gdw/L under the led lamp (3 Klux) and 0:24 light cycle respectively. No significant effects of different light sources on the microorganism lipid content were observed. The average lipid content of microorganisms each for applied light intensity was determined to be 45% and 17% for Chlorella protothecoides and Chlorella ESP-6 respectively. On the other hand, with the effect of the light cycles on the microorganism lipid content, it was seen that the lightness phase for Chlorella ESP-6 increased considerably. There was no significant effect on Chlorella protothecoides. The highest lipid contents were determined as 17% and 48% for both microorganisms respectively.

Recently, the synthesis of biolubricants has been the focus of researchers because of their good lubricating properties and environmentally friendly products. This study was performed to optimize reaction parameters for the enzymatic transesterification reaction between waste edible oil methyl ester (biodiesel, FAME) and trimethylolpropane (TMP) by using Response Surface Methodology (RSM). The parameters that affect the enzymatic transesterification reaction were chosen as temperature (35–55°C), amount of catalyst (0–10 %wt. of mixture), TMP-to-FAME molar ratio (0.17-0.33), and reaction time (0–96 h), to produce TMP triester (biolubricant). Response surface methodology (RSM) and three-level–four-factor Central Composite Design (CCD) were employed to evaluate the effects of these synthesis parameters on the percentage conversion of FAME by transesterification. Enzyme amount and reaction time were the most important variables. The optimum reaction conditions were determined to be the temperature at 50°C; the amount of catalyst, 5%wt; molar ratio, 0.25 and 48 h of reaction time, under these conditions 91% TMP ester's yield was obtained. The interaction parameter of the lipase quantity with the FAME to TMP molar ratio was found to be the most important among all of the other parameters.

Date Stem By-products (DSB) have been used as agricultural feedstock to perform bioethanol production in a batch bioreactor. To study the effect of an optimal mixture of fruit hydrolysates (20%dates, 20% Figs, and 20% sugar beet) on ethanol yield, different parameters have been followed up, including pH, total sugars, and ethanol yield. The optimal ethanol concentration was found for date stems by-products +20% dates, it was about 19.38 g/L after 72h fermentation process, in such case, the higher initial sugar concentration is close to 204.5 g/L, and the pH dropped from 4.5 to 4.21, while it was only about 18.48, 13.08 and 4.72 g/L for DSB+20% sugar beet, DSB+20% Figs, and DSB, respectively. The maximum bioethanol production rate (Rm) was about 2.633 (g/L/h) in the case of DSB+20% dates, which is higher compared to the other selected mixtures. The effect of some physical properties on the addition of ethanol/ETBE (Ethyl tertiary-butyl ether) to super-premium gasoline has been studied. It was found that the addition of 20% ethanol or ETBE to super-premium gasoline increased the Research Octane Number from 96 up to 99.3 and from 96 up to 99.8 in the case of DSB+20% dates and ETBE, respectively.

Poly (γ-glutamic acid) is a versatile biopolymer that can be used on an industrial scale if efficient methods are developed to increase production. In this study, first, based on the central composite design method of the response surface module, the effect of operational variables including temperature in the range of 30-44 °C, pH 4.5-8.5, and stirring in the range of 600-1000 rpm on poly (γ-glutamic acid) production was investigated in the batch fermentation of Bacillus licheniformis ATCC 9945a for the first time. Under optimal conditions viz. T of 37.4 °C, pH of 6.6, and agitation rate of 784.2 rpm, 15.5 g/L γ-PGA was obtained. According to the statistical analyses, adjusted R2 was 0.9572, and analysis of variance explicated that T-T, pH-pH, and agitation-agitation effects indicated the lowest p-values and had the most significant influence on biopolymer synthesis. Under the optimal conditions, glutamate (a novel feed) pulse feeding (as poly (γ-glutamic acid)-based monomer) was optimized, for the first time, using the one-factorial method to achieve a maximum of 42.13 g/L of biopolymer production (highest in comparison with others’ studies of this strain) by the two-pulsed feeding method. The chemical confirmation and novel physical characterization of the powdered product indicated a pure poly (γ-glutamic acid) sample suitable for biological, biomedical, and biopharmaceutical applications.

Chalcopyrite is the most abundant copper mineral in the world, and its bioleaching suffers from low dissolution rates, which is often attributed to passivating layers. Hence, these passivating layers must be overcome to use bioleaching technology to its full potential to process chalcopyrite. Leaching must occur at a low Oxidation/Reduction Potential (ORP) to prevent these passivating layers from forming, but chemical redox control in bioleaching heaps is difficult and costly. As an alternative, selected weak iron-oxidizers could be employed that are incapable of scavenging exceedingly low concentrations of iron and, therefore, raise the ORP just above the onset of bioleaching but not high enough to allow for the occurrence of passivation. This study isolated four bacterial strains from acid mine drainage in one of Mongolia’s most significant copper mining sites. Three of these strains were identified based on their partial sequence of the 16S rRNA gene. Also, we studied the electrochemical properties of the bioleaching process of sulfide ore by one of the isolates obtained from the acid mine drainage. Our results show that strains ER-1a and ER-1c are closely related to Candidate division OP10 bacterium P488 (AM749768), and ER-1d is closely related to Fimbriimonas ginsengisoli Gsoil 348 (GQ339893). Bioleaching of copper concentrate was monitored by the electrochemical method. During 18 days of oxidation, only three types of oxidations were observed. The solubility of copper reached 615 mg/L and 53.37%, while 83.7% of ferrous ions were converted to iron (III). The CV-cyclic voltammetry oxidation current peak intensity gradually increased until day 15 and then decreased on day 18 during the bioleaching experiment.

Some human activities cause soil and groundwater pollution. Physical and chemical processes are used to eliminate or reduce this contamination. However, these techniques are very expensive and can be very invasive to ecosystems. Bioremediation is a remediation process that uses bacteria's metabolic capacity to degrade organic pollutants. Certain parameters, however, have a significant impact on the development of the bacteria, namely the level of oxygen and the nutrient content, particularly nitrogen and phosphorus (N and P). In this study, the effect of these two parameters on bacterial reproduction and decontamination power on soil polluted by diesel oil at 10 g/kg was investigated. Bubble column bioreactors have been used; each bioreactor was filled with polluted soil. The experiments were carried out in two configurations, A and B, to characterize separately the biodegradation rate generated solely by bacterial activity and the removal rate generated by aeration. In the first case, bio-stimulation was used to increase the bacterial flora, while in the second, the bacterial flora was neutralized by using HgCl2. The contaminated soil was amended using NH4Cl, and KH2PO4, salts according to C/N/P molar ratios of 100/10/1, 100/5/1, 100/25/1, 10/10/3, and 100/10/0.33. The results showed a significant relationship between airflow rate, C/N/P molar ratio, and diesel oil removal on the one hand, and biomass growth on the other. After 26 days, the removal rates were 58, 70, 79, 78, and 97% for 0.25, 0.5, 1, 1.5, and 2 L/min, respectively, for a C/N/P molar ratio of 100/10/1. Furthermore, after 12 days, the best biodegradation rate was 36% with an airflow rate of 1 L/min and a C/N/P molar ratio of 100/10/1. It would be interesting to continue this research to determine the best conditions for increasing the rate of biodegradation.