نشریه علوم و مهندسی جداسازی
سال دوازدهم شماره 2 (پیاپی 24، پاییز و زمستان 1399)

The use of nanofiltration membranes has been attractive in many fields especially in water treatment due to high separation performance. The most used membranes are polymeric. However, the achievement of high mechanical stability and good separation performance is one of the important challenges for the application with various operating conditions. In this study, PES-based nanofiltration membranes were fabricated by the phase inversion method. The Fe3O4 nanoparticles with the concentration of 0.5 wt.% and different concentrations of sodium citrate were used in the membrane preparation. The FTIR analysis was used to investigate the formation of chemical bonding. Moreover, membrane morphology and surface topography were studied by FESEM and AFM analysis, respectively. The separation performance of membranes was examined by the contact angle, membrane porosity, water content, pure water flux (PWF), and salt rejection. The results showed the highest PWF (47 L/m2h) and salt rejection (68%) for M5 at 0.5 wt.% of iron oxide nanoparticles and 0.3 wt.% of sodium citrate. However, Na2SO4 rejection increased slightly compared with the pristine PES membrane (about 11%). But the PWF improved about 66% compared with the pristine PES membrane due to increase membrane hydrophilicity and better dispersion of Fe3O4 nanoparticles and the formation of more active sites for Na2SO4 adsorption. The good dispersion of nanomaterials led to reducing membrane roughness, and also the increase of hydrophilic groups led to improve antifouling properties of prepared membranes.

Azeotropic point is one of the most important limitations in petrochemical units that prevents the separation and purification of various materials and products. In this study, deep eutectic solvents were used as the brittle azeotrope breaker for a mixture of heptane and toluene. Recently, low eutectic solvents have become increasingly popular as environmentally friendly green solvents to replace volatile organic compounds (VOCs). These solvents consist of a combination of a hydrogen bond acceptor (such as choline chloride) and a hydrogen bond donor (such as urea, thiourea, and 1,2-propandiol). In this study, the deep eutectic solvents were synthesized with a ratio of 1:3 for choline chloride and thiourea as solvent number one, and a ratio of 1:2 for choline chloride and 1,2-propandiol as solvent number two, respectively. The separation process was performed at 298.15 K and atmospheric pressure. The predictive UNIFAC model, was used to model the mentioned systems. The mean deviation (RMSD) for the first and second systems were calculated to be 3.38 and 2.99, respectively.

Separation of airborne pollutants such as dust, bacteria, and viruses play an important role in humanitarian health. In this field, acrylic polymer with many properties such as electrospinning capability, thermal resistance, and high chemical resistance is attracting scientific and commercial interests as an active layer for fibrous filter media. The aim of this paper is to utilize low cost, natural resource, biocompatible, and high mechanical strength Halloysite nanotubes (HNTs) for improving filtration efficiency. In this regard, acrylic polymer nanofibers were fabricated by solution electrospinning method on nonwoven support with and without HNTs to fabricate nanocomposite and acrylic membrane. The structure and morphology of membranes were examined by Fourier-transform infrared spectroscopy (FTIR), electron scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX). Furthermore, the mechanical properties of the samples were analyzed using a single-axis tensile test. Finally, in order to evaluate the filtration efficiency measurement, DOP (dispersed oil particle) were utilized. The results reveal that the nanocomposite membrane has a better performance comparing to the acrylic membrane due to the separation of 95.5% of DOP particles. This layer could be applied as an active layer in N95 face mask.

Ni0.2-xCuxZn0.8Fe2O4 ferrite nanoparticle powders were prepared with special ratios (X = 0, 0.1, 0.2) by automatic sol-gel auto-combustion using microwaves. The resulting powders use X-ray diffraction, scanning electron microscopy, infrared spectroscopy, X-ray energy scattering, diffuse reflection spectroscopy and vibrating sample magnetometer and photocatalytic activity of the samples were analyzed by UV-Vis analysis. The average crystal grain size of magnetic nanoparticles was calculated using half-maximum full-width data (FWHM) and X-ray scattering according to the Dubai-Sherry formula. The results of the X-ray diffraction pattern showed that the obtained ferrite nanoparticles have a single-phase cubic spinel structure and do not have an impure phase. Careful observations through scanning electron microscopy have shown that nickel-zinc-copper ferrite nanoparticles were spherical in shape. From the IR peak of the octagonal and tetrahedral vibrations, the formation of the spinel structure was confirmed. The presence of nickel, copper and zinc elements in ferrite nanoparticles was confirmed by EDX analysis. The peak absorption of ferrite nanoparticles obtained from the diffusion spectrum (DRS) was 310, 438 and 315 nm, respectively. Finally, magnetic measurements show that ferrite nanoparticles are highly saturated with ferromagnetic matter. In following, the photocatalytic and adsorption activity of the samples for removing of methylene blue contaminants with concentration of 5 and 15 mg/mL were investigated in 3 times. It was shown that the ferrite sample containing only nickel had better absorption and destruction of the contaminant than other ferrite samples.

The growing global population on the one hand, as well as the scarcity of fresh water resources, are the reasons for the global water crisis. Therefore, to cope with these conditions, humans need to find alternative and renewable freshwater sources through the treatment of existing unhealthy waters or desalination of saltwater. Staircase solar water purifiers are among the many devices used in water purification. This paper deals with the simulation of a staircase solar water desalination at the University of Sistan and Baluchestan with Comsol software. After comparing the experimental data and the results of the software, the influence of saline depth parameter on the stairs on the amount of fresh water output from desalination was investigated. For this purpose, the performance of the device for saline water depths of 0.005, 0.0075 and 0.01 m with inlet saline flow rate of 0.2 (kg / min) was investigated. The results show that with increasing salt-water depth, the water temperature decreases and the temperature difference between the water surface and the glass surface decreases and the amount of fresh water produced decreases.

A microwave approach is being presented for the synthesis of sulfide nanostructures as well as two component composites between them. ZnS, CuS and heterojunction mixture between the two were obtained using the relative metal acetates and thiourea, i.e., sulfur source in N, N-dimethylformamide (DMF), which was utilized as both solvent and surface binding agent under microwave irradiation for just 20 seconds. The samples were characterized using field-emission scanning electron microscope, energy dispersive X ray, X-ray diffraction and diffuse reflectance spectrophotometry. Photo-degradation of methylene blue as a common pollutant was investigated as an application for the synthesized materials. Removal efficiency of about 60% after 30 minutes of contact in darkness and 60 minutes of illumination using low-power UVB light remained fairly unchanged after 5 running cycles. The obtained composite between ZnS and CuS is a p-n type heterojunction able to show better photocatalytic activity compared to each of the constituting sulfides alone.

Metal–organic frameworks (MOFs) are a new class of coordination polymers and porous materials which have a wide application in various scientific fields based on their dual structures. In this work, synthesis of γ-Fe2O3@SiO2@ZIF-8 magnetic nanocomposite for removal of organic pollutant from wastewater was studied. Then, for improving photocatalytic performance of this compound, silver nanoparticles were added into the ZIF-8 framework using photo-deposition method. Synthesized nanostructures were characterized using different structural analysis such as XRD, SEM/EDX, FTIR, ICP-OES and VSM. Next, the photodegradation performance of the prepared materials for removal of Rhodamine B were investigated by studying the effects of several parameters including photo-catalyst dosage, initial dye concentration and solution pH. The results showed that γ-Fe2O3@SiO2@ZIF-8-Ag photo-catalyst with the efficiency of 96% had the best performance in degradation of organic dye. Also, the stability tests showed that the synthesized photo-catalyst can maintain its appropriate activity after five cycles. Therefore, the proposed nanocomposite in this work seems to be a reusable and economical photocatalyst for water purification.

In this research, ternary nanocomposites, Ag/rGO-TiO2 (x) were synthesized through the photodeposition of different amounts of silver on titanium dioxide nanosheets (TNs) combined with reduced graphene oxide (rGO (. Different techniques such as XRD, FESEM/EDX, TEM, DRS and Raman spectroscopy were employed for structural and morphological characterization of the synthesized samples. The photocatalytic degradation experiments were carried out in the presence of 75 mg of the prepared samples in 100 mL of the aqueous solution of tetracycline with 30 mg/L concentration under visible light. The best photocatalytic performance was related to the ternary nanocomposite Ag/rGO-TiO2 (0.076) (synthesized in the presence of 0.076 g AgNO3) with the percentage of TC degradation equal to 52.56%, the can be attributed to plasmonic resonance of silver plasmonic nanoparticles. The removal percentage of tetracycline was 37.93% in the exstance of pure titanium dioxide nanosheets (TNs) under the same conditions. Adaptive neuro fuzzy inference system was used for modeling and prediction of the photocatalytic performance of the synthesized ternary nanocomposites.