bizhan honarvar

Activated carbon is known an as appropriate adsorbent due to its high adsorption capacity for most pollutants, especially heavy metals. In the present study, activated carbon was synthesized from orange wood by employing the chemical activation method. Additionally, cysteine amino acid was used to modify the activated carbon surface, leading to an enhancement in adsorption ability because of having a nitrogen group. Based on the results, the adsorption capacity of the modified activated carbon was obtained at 120 mg g-1 adsorbent. The parameters affecting adsorption such as the amount of used adsorbent, as well as solution pH, primary concentration, and contact time were optimized, followed by performing the adsorption process under optimal conditions. The optimal adsorption conditions included the pH of 6, contact time of 60 min, adsorbent amount of 50 mg, and primary cadmium concentration of 80 ppm. Further, kinetic and thermodynamic parameters were assessed and optimized. The results of which represented the best fit between adsorption with Langmuir isotherm and the pseudo-second-order kinetic model. The results represented that the quasi-second-order model with a higher regression coefficient (R2 = 0.97) described the experimental data better than the quasi-first-order one (R2 = 0.83). The adherence of adsorption kinetics to the pseudo-second-order model suggested a chemical interaction as the rate-determining step. Regarding adsorption thermodynamics, the effect of temperature was examined on adsorption by using Van't Hoff's equations, which reflect the endothermicity of the process.

In this study, the effect of various concentrations of alkyl polyglycoside (APG), aluminum oxide nanoparticles (Al2O3), and tetra-n-butyl ammonium chloride (TBAC) on the storage capacity of CO2 hydrate formation are investigated. For this aim, a laboratory system is developed. The experiments are carried out in the pressure range of 25 to 35 bar and the temperature range of 275.15 K to 279.15 K. The Experimental results showed that by increasing the system pressure at a constant temperature, the storage capacity increased by 48% on average. Decreasing the system temperature at constant pressure increased the storage capacity by 23% on average. Adding APG to the system at constant temperature and pressure increases the storage capacity by 75% on average, while adding nanoparticles of aluminum oxide increases the storage capacity by 5% and TBAC 38% on average. For statistical analysis of laboratory data, Design-Expert software and Response Surface test design method, and Quadratic model are employed and a mathematical relationship is developed with R2 = 0.9987 to estimate CO2 storage capacity in hydrates. The optimum amount of storage capacity equal to 137.476 has been reached at 34.558 bar, 276.085 K, 2.825 wt% of TBAC, 956.733 ppm APG, 2.436 wt % Al2O3.

Asphaltene precipitation, as stated in previous studies, plugs the pores in the porous media and causes various problems, including permeability reduction, wettability alteration, and ultimately reduces production. The results of this study showed that this surfactant is able to prevent asphaltene precipitation and is effective in different aqueous phases (DW, SW and CW). In addition to increasing recovery factor in the core flooding test, it was able to alter the wettability of the pores surface from oil-wet to intermediate.

In this study, a combined lab-scale purification system was set up to treat wastewater from the National Iranian Oil Company. The combined system was composed of three main sections: pre-filtration using activated carbon filter (ACF), electrocoagulation (EC) system, and a filtration section (MF followed by RO). The performance of the treatment system was evaluated by measuring heavy metals, BOD, COD, TDS, TSS, and O&G. The results showed that pre-filtration using ACF could lead to the removal of the BOD, COD, TDS, TSS, and O&G by 24.6%, 21.12%, 31.07%, 36.9% and 8.49%, respectively; the heavy metals were removed significantly. In the EC section, heavy metals were rejected by more than 98% using both the Al and Fe electrode, except for the Cr ions that were mostly removed with Fe electrodes. The removal of BOD, COD, TDS, TSS, and O&G using the Al and Fe electrode was 95.6%, 96%, 91%, 76.6%, and 98.6% and 93.2%, 92.1%, 76%, 83% and 99%, respectively. EC followed by MF/RO filtration led to a remarkable purification performance, and the rejection rate of all pollutants was obtained over 99% after this section. The experimental results indicated that the optimum time for ACF and EC processes were 20 and 50 minutes.

Experimental study of the effect of gas antisolvent (GAS) system conditions on the particle size distribution of finasteride (FNS) requires a thermodynamic model for the volume expansion process. In this study, the phase behavior of the binary system including carbon dioxide and  Dimethyl sulfoxide, and a ternary system comprising carbon dioxide, dimethyl sulfoxide, and Finasteride was studied. The Peng-Robinson equation of state was employed for the evaluation of the fluid phases and a fugacity expression to represent the solid phase. By developing an accurate predictive model, the GAS operating conditions can be optimized to produce particles with no need for a large number of experiments. First, the critical properties of the FNS were evaluated by the group contribution methods. The method of Marrero and Gani was also selected to predict the normal boiling point, critical temperature, and critical pressure. The correlation of Edmister was chosen for the prediction of the acentric factor. The lowest pressures for the ternary system at 308, 318, 328, and 338 K were 7.49, 8.13, 8.51, and 9.03 MPa, respectively. The precipitation of the dissolved finasteride happened at these operating pressures.

In the present study, developed polysulfone (PSF) hollow fiber membranes were fabricated via a phase-inversion process. In order to enhance the membrane porosity, non-solvent additives such as polyvinylpyrrolidone (PVP) and poly ethyleneglycol (PEG) were introduced into the polymer solutions. The prepared membranes were used in the membrane contactor modules for dehydration of nitrogen gas stream by triethylene glycol (TEG). The membranes were characterized in terms of scanning electron microscopy (SEM), nitrogen permeation, overall porosity, collapsing pressure and wetting pressure. From SEM analysis, the membranes prepared by PVP and PEG presented a porous structure with smaller finger-like cavities compared to the plain membrane. Results of gas permeation test showed that the developed PSF-PVP membrane had mean pore size of 112 nm and N2 permeance of 16900 GPU. Due to open structure of the PSF-PVP membrane, a good overall porosity of about 76% was obtained. The prepared membranes by PVP and PEG showed higher collapsing pressure due to the formation of smaller finger-likes and a thicker spongy sublayer. From dehydration test at liquid flow rate of 250 ml/min, the maximum vapor absorption flux of 6.6×10-7 m3/m2 s was achieved for the PSF-PVP membrane which was about 10% and 6.5% higher than the flux of the plain membrane and PSF-PEG membrane, respectively.

Supercapacitors have attracted much attention in the field of electrochemicalenergy storage. However, material preparation and stability limit their applications inmany fields. Herein, a reduced graphene oxide@phosphorus (rGO@P) electrode wasprepared using a simple inexpensive method. The new graphene structure (rGO@P) wascharacterized by X-ray di􀀀raction, Fourier transform infrared spectroscopy, scanningelectron microscopy and Energy-dispersive X-ray spectroscopy.Electrode showed excellent performances (307 F g−1), which seem to be the highestamong many other rGO@P-based electrodes reported so far. It also has an excellentcyclic stability up to 95% after 600 consecutive charge/discharge tests. So, the ease ofthe synthesis method and excellent performance of the prepared electrode materials mathave significant potential for energy storage applications.

Given that most of the gaseous constituents of industrial chimneys are usually carbon dioxide which is one of the most important greenhouse gases. It seems that the hydration process is one of the newest methods for the separation of this gas from gaseous mixtures. In the gas hydrate formation industry, in addition to disadvantages, there are some advantages such as gas separation, transmission, and storage. Therefore, it is important to determine the appropriate promoter for the formation of gaseous hydrates as well as to find the inhibitor. In this study, the effect of tetra-n-butyl ammonium chloride (TBAC) (which is a thermodynamics promoter) and alkyl poly glucoside (APG) as a nonionic surfactant on the surface tension of carbon dioxide hydrate formation process have been studied. The experiments were carried out in a 218 cm3 batch reactor. The surface tension of CO2 hydrate has been determined at different concentrations and different temperatures and pressures. The nucleation classical theory has been used for this purpose. Designing the experiments performed by Design-Expert software. The results show that increasing the APG and temperature leads to decreasing the surface tension and in contrast, induction time decreases, and the experimental model of the effect of these parameters on surface tension presented as R2 = 0.9898.

The fossil fuel sources are decreasing, and the use of biofuels has been recently considered. Among biofuels, biodiesel is considered more because of the environmental benefits. In this study, CaO/CuFe2O4/C nanocatalyst was used to produce biodiesel from Moringa oleifera oil. Different analyses such as TGA, EDX, XRD, FTIR, SEM, and TEM were applied to characterize physical and chemical properties of the CaO/CuFe2O4/C nanocatalyst. Also, Taguchi method was used to determine the biodiesel yield. Moreover, the effective parameters such as methanol/oil ratio (1:12 mol/mol), reaction time (4 h), reaction temperature (60 oC), and catalyst content (3%) were determined as optimal conditions on biodiesel production yield. Additionally, the maximum biodiesel yield was determined 98.69% in these conditions. Moreover, the physical properties of biodiesel/diesel mixtures like density, flash point, kinematic viscosity, pour point, and cloud point were studied, and the results were compared with ASTM D14214 and ASTM D 6751 standards. Finally, the results showed that these properties were in the standard range; in addition, pour point and cloud point are not proper for cold weather.

Natural gas and crude oil in natural underground reservoirs are in contact with water. Stability of these compounds at the presence of both components and complete dependence on the host molecules by forming holes in their guest molecules are replaced. There are many gases such as methane, ethane, propane, carbon dioxide, hydrogen sulphides that can play the role of guest molecules. The natural gas hydrate formation in different sectors of the oil and gas industry in downstream processes causes the production to stop or decrease. Therefore, the need to know the causes and conditions of hydrate formation is strongly felt. In this study, Van der Waals and Platteeuw model was used to predict hydrate formation conditions. The prediction of hydrate formation conditions needs equilibrium fugacity of gaseous components, and for the equilibrium molar component of water.

A new modified magnetic Graphene Oxide with Chitosan and Cysteine wassynthesized for removing Pb2+ ions from aqueous solution. The properties of thisadsorbent were characterized by Field Emission Scanning Electron Microscopy (FESEM),Vibrating Sample Magnetometer (VSM) and Energy Dispersive Analysis Systemof X-ray (EDAX). Physicochemical parameters such as effect of pH, contact time,adsorbent dosage and initial concentration of Pb 2+ was also studied. The results showedthat the maximum capacity of absorbent in Lead ions adsorption (at Equilibriumconcentration of 120 ppm) occurred at pHOptimum= 5.75, tOptimum= 30 min andadsorbent 85.4 mg/g dosage=0.1 gr. Maximum empirical adsorption capacity (qmax) wascalculated 85.4 mg/g. The thermodynamic parameters (ΔHᵒ, ΔGᵒ and ΔSᵒ) showed thatthe adsorption process of Pb 2+ on modified magnetic Graphene Oxide with Chitosanand Cysteine was endothermic and spontaneous. Removal percentage was reduced to15% after five stages of Sorption/desorption studies. So, modified magnetic GrapheneOxide with Chitosan and Cysteine can be used as a complementary process for removalof Pb2+ ions from water and wastewater.

This study has examined the use of a cylindrical parabolic collector (CPC) and solar panels in the solar still unit for more heating. The results of two different setups were then compared so that the first setup was a simple solar still unit and the second setup was a solar still unit with solar panels and the CPC device. The depth of saline water in the basin was 30 mm. Based on the results, the use of solar panels, thermal elements and the CPC device had a major impact on the amount of water sweetening during the experiments. In this paper, the experiments presented a new method for increasing the amount of water. With regards to the newly presented method, there has been a significant increase in the amount of solar energy absorbed in the whole process of water sweetening. Experiments were performed at 300-watt and 400-watt solar panels and CPC devices with lengths of 1 m and 2 m. The cooling of solar panels was also investigated and compared with the process without cooling.

Nanoparticles are promising materials with a variety of applications, whose surface modification is an important technique for developing these applications. In this study, a new nanostructure was synthesized in four steps that can be used to remove pollutants from wastewater. Firstly, the graphene oxide nanoparticles (GO) were synthesized by the modified Hummer method, and then by simultaneous precipitation of ferrous and ferric ions in based atmosphere on the surface of GO, graphene oxide was magnetized. Subsequently, magnetic nanoparticles of graphene oxide (m-GO) coated by chitosan saccharide polymer with covalent bonding. The magnetic graphene oxide nanoparticles coated with chitosan (m-GO@Chi) were bonded to the cysteine-glutaraldehyde schiff’s base (CG) with cross-linking method and their surface modified with cysteine (m-GO@Chi-Cys). After that, the nanoparticle surface correction process was investigated by using og identification analyzes. The results of the FT-IR spectroscopy indicated that surface modification was successful at each stage and the presence of epoxide, carbonyl, amino, and thiol functional groups at the nanoparticles level was confirmed. According to FESEM images, GO particles were synthesized in two dimensional and average thicknesses of 29-165nm and after magnetization, iron oxide nanoparticles with a mean size of 35-50nm were observed at the GO level. VSM analysis was used to study the magnetic properties of nanoparticles. The absence of residues in the nanosize magneticization curve and the negligible reduction in the saturation magnetization of m-GO@Chi-Cys nanoparticles, as compared to m-GO, is due to the presence of thin layer of chitosan on the primary particles.

During the drying process of food, systems undergo several simultaneous physical and structural modifications, undesirable from the viewpoint of material end use. Cubic squash samples were utilized as the test media in the fluidized bed dryer assisted infrared heat source. The effective moisture diffusion coefficient was expressed as a function of temperature and average moisture content. Some correlations have been developed for shrinkage and density of the drying materials. The effect of air temperature, inert materials amount, air velocity and IR power on drying rate were investigated.