Iranian Journal of Chemical Engineering (IJChE)

Abstract In this study, Nano filtration (NF) membranes composed of polyethersulfone (PES) modified with titanium dioxide (TiO₂) nanoparticles were fabricated using the phase inversion method. By grafting aniline oligomers onto the surface of the modified membrane, the final membrane with the structure PES NF/TiO₂/AO was fabricated. The morphology of the final membrane was investigated using FESEM, EDX and FTIR analysis. Membrane separation performance was evaluated through contact angle measurement, pure water flux (PWF), flux recovery ratio (FRR%), and salt rejection tests using Na₂SO₄ and MgSO₄ solutions. The highest PWF (3.66 kg/(m^2.h)) was obtained with the final modified membrane compared to the initial membrane at an operating pressure of 4.5 bar, which can be attributed to the increased hydrophilicity that can be attributed to the surface modification of the initial membrane. The removal efficiencies for heavy metals Pb and Cu using the pristine membrane were measured at 28.2% and 43%, respectively, while the optimized membrane showed significantly improved rejection rates of 99.97% and 94%. Furthermore, the total fouling rate of the original membrane was approximately 70.4%, which was reduced to 47.4% in the modified membrane. The irreversible fouling was reduced from 44.5% in the original membrane to 32.6% in the optimized membrane, indicating an improvement in the antifouling performance of the modified membrane. The results suggest that the PES NF/TiO₂/AO modified membrane can be considered an effective approach for enhancing the physical and chemical properties of membranes, as well as their separation performance, particularly for the removal of heavy metals.

Abstract In this research, a mixed matrix membrane based on polysulfone and zinc nitrate-methylimidazole fillers was synthesized to improve the ability of the polymer membrane for the separation of CO₂ and CH₄. The membranes were fabricated using the solution casting technique and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR-ATR), energy dispersive spectroscopy (EDAX), and gas permeability tests. The FTIR-ATR analysis confirmed the presence of the functional groups. XRD results demonstrated an even dispersion of the additives throughout the polymer matrix, by the quantitative analysis revealing a reduction in the crystal size and percentage. The EDAX analysis confirmed the consistent spread of ZIF-8 particles in the polymer. The gas permeability tests showed a significant increase in the permeability and selectivity of the mixed matrix membrane compared to that of the pure polysulfone membrane. The presence of ZIF-8 particles enhanced the permeability of CO₂ by expanding the available space within the polymer and promoting the solubility of CO₂. Additionally, the increased free volume improved the diffusion coefficient of CH₄ and led to a slight increase in its permeability. The permeability of CO₂ increased from 76.72 GPU for the pure polysulfone membrane to 322.95 GPU for the mixed matrix membrane, while the permeability of CH₄ increased from 31.21 GPU to 61.27 GPU. The selectivity of CO₂/CH₄ exhibited a notable increase from 2.46 to 5.27. This improvement in selectivity can primarily be attributed to the significantly higher increase in the solubility coefficient of CO₂ compared to that of CH₄.

Abstract The optimization of membrane bioreactor (MBR) equipped with a submerged flat-sheet polyethersulfone (PES) membrane for the wastewater treatment from dairy processing facilities was investigated. The effects of key parameters such as the hydraulic retention time (HRT, from 8 to 16 hr), mixed liquor suspended solids (MLSS, 3000 to 9000
mg/L), and rate of aeration (Qair: 1 and 2 L/min) on COD removal efficiency were systematically investigated. Through the response surface method (RSM), the maximum the COD removal efficiency of 92.67% was obtained under the optimal conditions of HRT: 13.83 hr, MLSS: 7239.84 mg/L, and Qair: 1.75 L/min. The statistical analysis identified MLSS as the most influential factor in the COD removal efficiency, accounting for 30% of the variation, followed by HRT with
16%, and the rate of aeration showing the least impact of 8%. A notable reduction in the UV absorbance of wastewater between 200 and 500 nm, after treatment using MBR under optimal conditions, signified successful targeting of toxic or colored pollutants. Finally, a mechanism for the wastewater treatment in MBRs, which included the biological degradation, adsorption on the surface of biomass and membrane, and separation through membrane filtration, was proposed.

Abstract In this research, the methods of oxidation, oxidation along with carbon nanotubes and surface absorption of carbon nanotubes were investigated to remove the drug substance of cefixime from aqueous solutions. In these methods, the removal percentage of cefixime was 78%, 96% and 70% respectively. Therefore, the results showed that oxidation with carbon nanotubes had a positive effect on the removal of cefixime. For this reason, oxidation along with carbon nanotubes was used to remove the cefixime. Next, different operating parameters such as the concentration of drug pollutants (20,30,40 and 55ppm), reaction time (5,10,15,20,25 and 30 min), concentration of hydrogen peroxide (1, 3 and 5ml) and amount of carbon nanotubes (0.05, 0.01 and 0.2 g/l) were studied in the removal process of cefixime using the method of  oxidation along with carbon nanotubes. It should be noted that in all experiments, certain amounts of carbon nanotubes and the oxidizing agent of hydrogen peroxide were used. In addition, a mixer, with a given round, was used to mix the materials. The maximum removal efficiency of cefixime from aqueous solutions is about 96% , which is related to the process of the removal of cefixime at the constant concentration of 55 mg/L by 0.1 g/L of carbon nanotubes and 5ml of hydrogen peroxide at the  t = 30 min.

Abstract The increased demand of the world for energy and its reliance on fossil fuels ultimately contribute to the surge in the levels of carbon dioxide in the atmosphere. To achieve a green, efficient carbon capture, a novel multi-component amine-amino acid solvent including methyldiethanolamine (MDEA), diisopropanolamine (DIPA), and Arginine (ARG) was designated for the CO₂ absorption in a T-microreactor. The potential absorption of the aqueous solutions of the desired mixed amines has been assessed through the CO₂ absorption percentage (AP) and the total volumetric gas-phase mass transfer coefficient (TGMTC) over a wide range of the gas flow rates (60-240 mL/min), solvent flow rates (2-6 mL/min), under the three mixing concentrations of MDEA: DIPA: ARG (28:8:4), (28:6:6), and (28:4:8)) wt%. The research findings demonstrate an increment of 31% in the absorption percentage of CO₂ by reducing DIPA to 4 wt% and raising the concentration of arginine to 8 wt% in the ternary amine solutions. Additionally, the highest mass transfer coefficient of 38.06 (kmol/m³.h.kPa) was achieved utilizing the aqueous solution of MDEA+DIPA+ARG (28+4+8) wt%.
 

Abstract Vacuum swing adsorption (VSA) for CO₂ capture has been a focus of significant research efforts aimed at developing innovative CO2 adsorbent materials. In this study, three adsorbents (MAF-66, AC, and CMS) were utilized for capturing CO₂ from flue gas through the VSA process, and their performances were compared. The adsorption equilibrium and kinetics data were gathered from recent literature. A four-step VSA cycle was employed to assess the adsorbents' performance for CO₂ capture, with a molar feed composition of CO₂:N₂ at 15:85%. Simulations of two-colums VSA lab-scales with different adsorbents were conducted. The operating conditions such as total feed flowrate, feed composition, feed pressure, temperature, and vacuum pressure were kept constant, and the impact of the adsorbent mass on recovery and productivity was analyzed. The simulation results indicated that both recovery and productivity decreased with increasing adsorbent mass. Furthermore, the necessary amount of each adsorbent to achieve a purity of 99.5% was determined. The modeling outcomes suggested that the VSA process employing MAF-66, CMS, and AC adsorbents would require 1.25, 3.19, and 8.2 grams of the adsorbent, respectively, to achieve N₂ purity of 99.5%. Taking into account parameters such as recovery, productivity, and energy consumption, MAF-66 emerged as the most effective adsorbent in this study.

Abstract Amine gas sweetening is a process in which acidic gases including hydrogen sulfide (H₂S) and carbon dioxide (CO₂) are removed by a solution of water and amines. Many parameters influence the sweetening process. Knowledge about the important parameters and their degree of importance is of great interest to achieve the optimum condition. Nine effective parameters including the CO₂ and H₂S contents of the feed, the temperature and pressure of the feed, the tray number and pressure of the absorber, the lean amine temperature, and the concentrations of Methyl Diethanol Amine (MDEA), and Piperazine (PZ) have been chosen as effective variables, while CO₂/H₂S recovery and total process energy have been considered as response variables.  After the verification of the present study with real plant data, the experimental layout was designed by the Plackett-Burman approach, and the model validation has been confirmed by ANOVA. The results of the present study showed that the most effective parameters in the CO₂ recovery are the absorber tray number and PZ concentration, while in the H₂S recovery, the absorber tray number is the most important variable. Regarding the total energy of the proces, feed temperature, PZ concentration, absorber tray number, lean amine temperature, and feed pressure are obtained as important variables. The optimum condition has been obtained in the feed and absorber pressures of 5758.9, and  1458.9 kPa respectively, with the feed and lean amine temperature of 0.11 and 50  respectively, the concentrations of 17.57 and 3.8 wt.% of MDEA and  PZ respectively, the absorber tray number of 20 and the mass flow rates of 792 and 103.6 kg/h of CO₂ and H₂S respectively. Under the mentioned conditions, the CO₂ and H₂S recovery were achieved at 99.99 % while the total energy of the process was 3.56 Mw.

Abstract The cementation reaction of Ni-Cd occurs on the surface of zinc powder, and the Ni-Cd ions in the zinc sulfate solution (make-up) change into a solid metal deposit during the process. The primary purpose of this study is to evaluate the effect of the particle size of zinc powder on the operational parameters of cementation, such as the quantity of the zinc powder used, the reaction temperature, and the contact time. These parameters are influential on cost reduction as well as the manufacturing rate of zinc ingot. Results indicated that providing that the zinc powder, -325 mesh, is used, the consumption of zinc powder used in the industry can be reduced by an average of 40%. It was also confirmed that the best times for the cementation of Ni-Cd for all studied sizes were 75 and 60 minutes respectively. The Ni and Ca were removed in -325 mesh to the optimal values at 85℃ and 65℃ respectively. By optimizing the evaluated parameters, the concentrations of Ni and Cd impurities were obtained at the lowest possible and acceptable levels for transferring the make-up solution to the electrolysis stage.

Abstract Polysulfone-zinc oxide mixed matrix membrane (MMM) was fabricated. A polyamide layer was formed on the top surface of the membranes using interfacial polymerization process. The properties and structure of the membranes were investigated and the membranes were used for desalination in reverse osmosis process. Cross-sectional images of the membranes substrate showed that the addition of zinc oxide to the polymer matrix resulted in a denser structure and increased the thickness of the sponge-like layer near the lower surface of the membrane. The addition of zinc oxide to the polymer matrix decreased the surface contact angle of the membrane with water, thereby increasing the hydrophilicity of the membrane. The pure water flux of all membranes reduced at the beginning of the process and after 60 min remained almost constant at the values of 19.50 (Lm-2h-1) and 30.20 (Lm-2h-1) for the membrane made with plain polymer and the MMM, respectively. In the reverse osmosis process, the water flux of the membrane fabricated using plain polymer was 9.70 (Lm-2h-1) which increased by 39% and reached to 13.50 (Lm-2h-1) by the addition of zinc oxide nanoparticles. The salt rejection of plain polysulfone membrane was 92.5% which increased to 97.21% with the addition of zinc oxide to the polymer matrix. The addition of zinc oxide nanoparticles to the polymer matrix significantly decreased the water permeability to salt permeability ratio (B/A) from 40.54 to 14.35 (kPa).

Abstract The Mixed Matrix Membrane (MMM) concept consists of incorporating suitable polymers with inorganic or organic fillers. The majority of polymeric membranes maintain a trade-off between permeation and selectivity, which restricts their development in separation applications. In this paper, less reviewed challenges on development of MMMs, such as the preparation of mix-matrix resistant membranes for industrial gas separation applications, as well as the use of appropriate and compatible fillers for different types of polymers were discussed. The MMMs comprising Metal Organic Framework (MOF) fillers were extensively studied. The importance of MOFs includes finely tunable structures, excellent compatibility with polymer matrices, and molecular sieve action. MMMs are considered promising structures that combines the advantages of polymeric and inorganic membranes. They exhibit the potential to upgrade the separation performance of pure polymer membranes using filler materials, whereas the cost remains relatively lower than that of pure inorganic membranes. The development of novel filler materials makes a substantial contribution in terms of role-playing.

Abstract The polysulfone mixed matrix membranes (MMM) with different concentrations of graphene oxide (0, 0.25, 0.5 wt % of the polymer) are fabricated by a phase separation method. The cross-sectional structures and their upper surface were assessed by the (SEM) surface roughness of the membranes assessed by (AFM). The mechanical and thermal stability of the fabricated membranes were evaluated as well. The separation of Carbon dioxide, nitrogen and methane from natural gas was considered. Also, by increasing the concentration of graphene oxide in the polymer matrix, the thickness of the spongy structure increases and the holes of the finger-like membranes are also destroyed. From the cross-sectional images of the outer surface of the MMM, it was concluded that an active selector layer was created on the lower surface of the membrane. The membrane tensile strength and the length of the membrane at fracture point increased slightly with an increase in the concentration of graphene oxide. Transition Glass temperature of the membrane increased by the addition of graphene oxide to the structure. From TGA analysis, in the presence of graphene oxide, the thermal stability improved. From the gas permeation test, by the addition of 0.25 % of graphene oxide to the polymer, CO₂ permeability was increased from 61.22 GPU to 76.04 GPU, while the addition of 0.5 wt % resulted in a lower permeability (69.55 GPU). The Nitrogen gas permeation flux of membranes decreased from 10.93 GPU to 3.91 GPU by the addition of 0.50 wt % of graphene oxide. The Methane gas permeation flux is reduced from 11.31 GPU to 6.95 GPU and 4.92 GPU by the addition of 0.25 % and 0.50 % of graphene oxide respectively. In conclusion, an increase in the concentration of graphene oxide increased the carbon dioxide selectivity.

Abstract A new approach is proposed to evaluate various designs for gas-solid cyclone separators. This approach uses single-phase flow simulation results to find a quantitative measure of flow symmetry in a given cyclone. Flow symmetry is computed by averaging imbalances of   non-axial velocities throughout the cyclone. Using this approach, two standard design methods are evaluated and the cyclone with a more symmetric flow pattern is chosen as a starting point for further design improvements by reducing the diameter of its vortex finder. Two-phase computational fluid dynamics (CFD) simulations compute 90.2 % collection efficiency for the improved design. CFD simulations reveal using a cascade of four cyclones results in an overall 99.98 % collection efficiency. Once installed in the actual industrial setting, the cyclone cascade achieves a 98.56 % collection efficiency and a particle size distribution which is in good agreement with CFD computed results.

Abstract The thickening of the iron ore tailings allows process water to be partially recovered and recirculated, also it reduces the fresh water consumption, which results in lower operating costs and less environmental impacts. The settling characteristics of the mineral components of an iron ore tailing in the thickening process may be different under various pulp conditions. Hence, the study of the characteristics of the mineral components of the iron ore tailings separately can provide very useful information about the thickening of an iron ore tailing. In this research, the settling behavior of the main mineral components of iron ore tailings including quartz and magnetite have been investigated under various operational conditions. The quartz and magnetite showed different settling behaviors, so as the maximum settling rate of quartz was achieved under different pulp conditions than that of magnetite was. There was a big difference between the maximum settling rates of quartz and magnetite, as the maximum settling rates of quartz and magnetite were 197 and 873 m/h respectively. In the thickening of an iron ore tailing, the pulp conditions must be set based on the settling behavior of the mineral component with the lowest settling rate.

Abstract  In an Iranian zinc smelter plant, nickel and cadmium are removed from the electrolyte solution at the cold purification stage with the help of zinc powder. This study tries to investigate the optimal conditions for the removal of these impurities through the response surface methodology by examining the effects of effective parameters on the process. The results of the experiments showed that cadmium was cemented by zinc powder much more conveniently than nickel. The interplay of parameters showed that increasing the concentration of zinc powder can reduce the time and temperature of the entire reaction. It also neutralized the effect of the changes of pH and mixing speed. The optimum conditions for the simultaneous removal of nickel and cadmium were obtained at 75 °C, the pH of 4.5, the residence time of 45 min, the mixing speed of 500 rpm, and 2 g/l of zinc powder. Under optimal conditions, more than 99 % of nickel and cadmium were removed from the electrolyte solution.

Abstract Nowadays, forward osmosis (FO) with many advantages in water treatment, are so attractive for researchers and investigators that the studies are going to optimize and increase its efficiency. However one of the most controversial operating malfunctions of FO process is fouling that limits the FO global application. In the following research, vertically aligned carbon nanotube (VACNT) on alumina membrane is introduced with high water permeability and less biofouling potential in forward osmosis for seawater osmotically dilution systems. VACNT membranes were prepared via pyrolysis of polymer into the pores of alumina. The effect of the temperature of pyrolysis process on CNT’s structure are assessed which indicated crystallinity of the CNTs increase in higher pyrolysis temperature of 800 °C. A small scale setup is designed for FO analysis and measurements of biofouling, flux and the effect of osmotic pressure were measured. Furthermore, all analysis were compared with commercial TFC membrane and results demonstrated that VACNT membrane has 40% less biofouling potential and 2 times better flux results.

Abstract A new method is developed to enhance the gas separation properties of mixed matrix membranes (MMMs) by interior modification of an inorganic nano-porous particle. Ship-in-a-bottle (SIB), as a novel synthesis strategy, is considered to encapsulate a polyaza macrocyclic Ag-ligand complex into the zeolite Y, which is resulted in a new host-guest nano-composite. It is consequently incorporated into a glassy polymer matrix to fabricate a novel MMM for CO2 separation. Accordingly, cellulose acetate (CA) with relatively low gas permeability is selected as the membrane polymeric matrix to provide an appropriate opportunity for better tracking the effect of incorporating the new synthesized nano-porous hybrids. The results showed a promising increase in both the CO2 permeability (45.71%) and CO2/N2 selectivity (40.28%) of the prepared MMM over its pristine CA membrane. It can be concluded that the proposed method makes it possible to fabricate novel MMMs with significant intensification in performance of the current MMMs.

Abstract Reverse osmosis is a commonly used process in water desalination. Due to the scarcity of freshwater resources and wastewater problems, a lot of theory and experimental studies have been conducted to optimize this process. In the present study, the performance of reverse osmosis membrane module of salt–water separation was simulated based on computational fluid dynamics technique and solution-diffusion theory. Eight geometries of membrane modules four flat sheets, and four tubular membranes were investigated. It was found that if the membrane surface area and inlet flow rate were kept constant for the eight modules, the pressure drop and permeated flow rate would be approximately similar for some geometries (such as the performance of primary flat sheet channel is same as 3 tubular membranes with R=1/3 Rref). The results also showed that because of the phenomenon of concentration polarization, if it is possible to use more membranes with a smaller length, it can reduce the pressure drop and increase the permeation flux of water. Furthermore, the results showed that in similar conditions between the tubular and the plate membranes; the tubular one is more suitable for the water permeation due to its ease of construction and its ability to withstand ECP.

Abstract At this work, removal of Pb (II) using Lawsonia inermis (Henna) was studied. In recent years, use of low price adsorbent is taken into consideration. Adsorption experiments were performed in batch system at ambient temperature (25℃). The influence of some parameters such as time, initial metal concentration, pH and adsorbent dose were investigated. The optimum conditions was obtained at pH of 6, 10 ppm of initial metal concentration, 80 min of contact time and 0.75 g/L of adsorbent dose. To study the adsorbent morphology, Scanning Electron Microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) was used before and after adsorption of Pb (II) ions. Sorption of Pb (II) was evaluated by Freundlich and Langmuir isotherms. The results indicate that the Freundlich isotherm model is better described the adsorption of Pb (II) than Langmuir isotherm model. Also, it is observed that, the pseudo-second-order kinetic model well fitted to experimental data .

Abstract In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum condition was revealed as solvent: metal ion molar ratio of 4.6:1, ligand: metal ion molar ratio of 318:1 and temperature of 23℃. The physio-chemical properties of as-synthesized ZIF-67 were investigated by BET, XRD, FTIR and FESEM analyses. Effect of adsorption pH, adsorbent dosage, initial concentration and contact time on adsorption process was investigated. Based on the results, the maximum adsorption capacity of Cr(VI) was 26.27 mg/g which was obtained at 35℃, pH= 5, adsorbent dosage of 3 g/l and initial concentration of 107.82 mg/l. The equilibrium time for Cr(VI) adsorption varied from 180 min for low initial concentration of 9 mg/L to 240 min for a high initial concentration of 90 mg/L. For the synthesized ZIF-67, maximum uptake capacity was reported 26.27 mg/g at initial concentration of 107.82 mg/l. The equilibrium data were described better by Langmuir-Freundlich isotherm model than the other models at three different temperatures. Pseudo-second-order model fitted the experimental data better than pseudo-first-order one. Adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous in nature. The regenerability of ZIF-67 was also studied in three sequential cycles and the Cr(VI) adsorption was almost retained after two cycles.

Abstract In this work, extraction of propionic acid from the aqueous phase to the organic phase (1-octanol) was performed in T-junction microchannels and effects of channel diameter and fluid flow rate on the mass transfer characteristics were investigated. The two-phase flow patterns in studied microchannels with 0.4 and 0.8 mm diameters were observed. Weber ‎ number and surface-to-volume ratio were calculated for evaluating flow patterns. Moreover, the effect of volumetric flow rates on the extraction ‎efficiency, volumetric mass transfer coefficient, and pressure drop was examined. Results showed that the pressure drop in the microchannel with 0.4 mm diameter is 2-2.7 times higher than that in the microchannel with 0.8 mm diameter. In both microchannels, with increase in flow rate, the extraction ‎efficiency first increases and then decreases. In addition, at high flow rates (2.4, 4.5 and 6 mL/min), the extraction ‎efficiency in the microchannel with 0.8 mm diameter increased up to the range of 7-14.9 % compared with that in the microchannel with 0.4 mm diameter.

Abstract This paper reports the evaluation of adsorbing Cr (VI) ions on sorbent prepared from chitosan (CHT), a versatile derivative of chitin, and dodecyl amine modified locally available kaolinite clay (Bijoypur clay) (MC) that has excellent mechanical properties and great resistance to chemical and biological attack. The effect of the initial metal ion concentration, solution pH, contact time, and adsorbent dosages on the adsorption capacity of the composites was investigated. pH 4 is selected for better adsorption by the adsorbents. The adsorption abilities were studied over Cr (VI) ions using different adsorption isotherm such as Langmuir, Freundlich, and Dubinin-Radushkevich respectively. Langmuir isotherm is found better fitted with maximum adsorption capacity of 73 mg/g by composite SB-1. R2 obtained from Langmuir isotherm is 0.999 which indicates a monolayer adsorption on the adsorbent surface. The adsorption kinetics was also well described by the pseudo-second-order equation with a rate constant of 0.000302 g mg−1 min−1 at 25 ppm Cr(VI) concentration. The adsorption of Cr (VI) ions by the adsorbent were confirmed by FT-IR and X-RD analysis of the composites before and after Cr (VI) ion adsorption. The desorption percentage of the metal ion and the second cycle metal adsorption by regenerated (regenerated after the first adsorption by fresh adsorbent) adsorbent processed with 0.01N sulphuric acid shows a value of 78.23% and 68.12% respectively.

Abstract In this work, an improved single-column chromatographic (ISCC) separation process is proposed. The term `improved' refers to both conceptual and physical modifications compared to the available single-column processes, including a novel fraction collection scheme and allowing overlapped peaks from adjacent cycles. Also the fraction collection mechanism was modified in order to facilitate online monitoring. Another advantage of the ISCC process is its large degree of freedom as injection volume, cycle time, solvent flow rate, feed concentration, and fraction-collection intervals can all be decision variables in this process. The experimental implementation and validation is covered in this work. The results indicate successful operation of the ISCC process and accompanying peripherals for the separation of guaifenesin enantiomers. In particular, the tests confirmed the integrity of the online monitoring system and proved the capability of the process for 98% purification of the tested enantiomers with an advantageously shorter cycle time, which results in higher productivity.

Abstract In this study, extraction of tannic acid using microchannel was investigated. Affective parameters were optimized. Different solvents including buthanol, ethylacetate and n-hexane as organic phase, methanol, propanol, ethanol and water as aqueous phase investigated. Microchannels with different confluence angles and diameters were examined. Microchannels with different confluence angles and diameters were examined. The effects of pH, temperature, and volumetric flow ratio and contact time of the two phases were investigated. The response surface methodology was used to optimize extraction yield of tannin from Quercus leaves in the employed microchannels. Based on this optimization, maximum yield was achieved at pH=2, temperature=33.1℃, volumetric flow ratio =1.2 and contact time of 25.35s. Results show that extraction-using microchannel has many advantages over traditional methods, including shorter time and higher economic efficiency. Moreover, microchannel provides smaller volume of fluids resulting in lower solvent consumption, lower waste production, shorter analytical times, smaller space requirements, and lower energy consumption.

Abstract The present study investigates the potential applicability of the extracted pectin from sour orange pomace as adsorbent for Ni (II) removal from aqueous solution. Pectin extraction from the pomace was carried out using HCl and the highest pectin extraction yield of 26.75% was obtained. The Fourier transform infrared (FTIR) spectroscopy analysis confirmed that the structure of the extracted pectin was similar to the commercial one. The morphology and chemical characteristics of pectin beads were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) techniques. The influence of several parameters including pH, initial metal concentration, adsorption temperature and time was studied to optimize nickel removal. The maximum Ni (II) removal of 85.1% was obtained at initial concentration of 20 mg/L and the highest adsorption capacity of 19.76 mg/g was achieved at nickel concentration of 100 mg/L. Kinetic and equilibrium studies were done to evaluate Ni (II) sorption from aqueous solution by the synthesized beads. Results showed that the sorption process follows a pseudo- second- order kinetic model. The equilibrium data were well correlated with Langmuir and Redlich-Peterson models by high regression coefficients.

Abstract Novel electrospun nanofibrous CS-PEO nerve conduits containing 0, 2.5 and 5% of green tea methanolic extract were developed and characterized by FE-SEM, FT-IR, TGA/DSC as well as tensile strength analysis. The FE-SEM images revealed that all of the nanofibers had an average diameter of ∼80nm. The swelling degree was decreased by increasing the GT amount from 2.5 to 5% and this might be attributed to the enhanced interactions of the NH2, C(O)NH2 and OH groups of chitosan and PEO polymers with the OH groups of GT leading to a less hydrophilic mat surface, thus reducing the attraction by the aqueous medium. Moreover, the swelling was the highest in acidic medium but it was decreased in the neutral environment and it had the least value within the alkaline medium. The CS-PEO-5%GT exhibited the highest antibacterial activity among three samples examined against both S. aureus and E. coli microorganisms. The CS-PEO-5%GT was proved to be a very suitable candidate to be used as nerve conduit due to its improved tensile and antibacterial activities.