فهرست مطالب fahime parvizian

In this study, polyethersulfone (PES)-based nanofiltration (NF) membranes were prepared by introducing synthesized oleic acid-titanium oxide (OA-TiO2) nanoparticles by phase inversion method. Various concentration of OA-TiO2 nanoparticles were used to the membrane fabrication. The OA-TiO2 nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and X-Ray Diffraction Analysis (XRD). Moreover, the membrane morphology was investigated by FESEM, 3D surface images. The separation performance of membranes were studied by the contact angle, pure water flux (PWF), flux recovery ratio (FRR%), and the rejection of Na2SO4 and CrSO4. The best pure water flux (18.206 L/m2h) was revealed for M2 with 42% increase compared with neat PES membrane at operation pressure 4.5 MPa due to increase membrane hydrophilicity and better dispersion of OA-TiO2 nanoparticles. Furthermore, the best Na2SO4 rejection (81.5%) was obtained to M3 and the highest CrSO4 removal (80.4%) was revealed to M5 at operation pressure 4.5 MPa. The enhancement of salt rejection attributed to Donnan effects and adsorption mechanism. The incorporation of OA-TiO2 nanoparticles into the PES improved the anti-fouling properties and FRR% increased to 83%.

A thin film nanofiltration membrane was modified by poly(vinyl alcohol) (PVA) and chitosan-functionalized activated carbon nanoparticles. The effect of a surface layer formed on the structure and separation properties of prepared membranes was investigated.

Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), water content, porosity and mean pore size measurements, Na2SO4 and NaCl rejection, water flux as well as membrane flux recovery ratio for the study of antifouling ability were used for characterization of the membranes.

The FTIR results confirmed the formation of hydroxyl and amine groups on the surface of modified membranes. The SEM images also showed the formation of a uniform layer on the modified membranes. As shown in the SEM images, adding functionalized activated carbon nanoparticles into PVA leads to a heterogeneous and dense structure on the surface of modified membranes. Modification of pristine membrane by PVA and modified activated carbon nanoparticles up to 0.25% wt initially increased the water content, and subsequently with increase in nanoparticles ratio from 0.25 to 1.0% (wt), the water content decreased. The obtained results showed a larger mean pore size for all modified membranes compared to pristine membrane. Moreover, all modified membranes showed a higher flux in comparison with virgin membrane. In addition, salt rejection revealed that the surface modification of nanofiltration membrane has a positive effect in preventing smaller rejection amount despite the increase in the amount of flux. Sodium sulfate salt rejection was also measured more than sodium chloride salt rejection. Flux recovery ratio was also measured more than 92% for the modified membranes whereas it was more than 66% for pristine membrane that confirms the antifouling ability for the modified membranes.

In this research, the effect of blending polyvinylchloride/polyethylene glycol on Physico-chemical and separation characteristics of heterogeneous cation exchange membranes was studied. Heterogeneous cation exchange membranes were prepared by using the phase inversion method through the solution casting technique. Obtained results showed that membrane water content and surface hydrophilicity were enhanced by an increase of PEG ratio in the membrane matrix. The membrane ion exchange capacity, charge density, membrane potential, transport number, and selectivity initially were improved by the use of PEG concentration up to 4 %wt in membrane matrix and then began to decrease by more PEG ratio from 4 to 16 %wt. The membrane ionic permeability and flux were enhanced initially by an increase of PEG content ratio up to 2 %wt in membrane matrix and then showed decreasing trend by more PEG loading ratio from 2 to 8 %wt. The ionic permeability and flux were enhanced again by more increase of PEG concentration from 8 to 16 %wt. The membrane areal electrical resistance was decreased sharply by the use of PEG in the membrane matrix. The membrane transport number and selectivity were also increased by an increase in electrolyte concentration. Membrane showed higher transport number and selectivity at neutral pH compared to other pH values. Results show that the modified membrane in this study is comparable with that of commercial membranes.

In this research, polyether sulfone (PES)/ polyvinylidene fluoride (PVDF) nanocomposite membranes were prepared form hydrophilic ZnO nanoparticles by phase inversion process. The effects of different concentrations of nanoparticles were investigated in terms of separation performance. In addition, the prepared membranes were characterized by SEM and AT-IR analysis. The results showed that the water content membranes increase from 77.96% in M1 (without nanoparticle) to 79.60% in M3 for 0.1 wt.% of ZnO, and the highest pure water flux was observed 19.97 L/m2h in 0.1 wt.%. Furthermore, the Na2SO4 rejection increased from 59% in M0 to 832% in M3. Thus, M3 showed the best performance separation among all prepared membranes. Ultimately, this study shows the potential PVDF-PES/ZnO membranes for application in wastewater treatment.

In this study, titanium dioxide nanoparticles were functionalized by L-cysteine/POSS and then utilized in fabrication and modification of PEI-based nanofiltration membranes. The FTIR results confirm the formation of composite nanoparticles decisively. Also, SEM and AFM were used in membrane characterization. The water permeability and separation performance of prepared membranes were studied by pure water flux and salt rejection considering. Obtained results showed that PWF increased up to 22.03 (L/m2.h) by applying 0.1 wt.% composite nanoparticles due to hydrophilic agents on the membrane surface. Moreover, the sodium sulfate rejection reached to 78% in modified membranes in comparison with pristine membrane. The modified membranes which contain composite nanoparticles showed more efficiency compared to the blended membrane with L-cysteine/POSS and pristine membrane. The results also exhibited improved antifouling ability for modified membrane in comparison to pristine membrane.