فهرست مطالب mahsa nemati

In this research, the effect of electrolyte concentration and pH effects on transfer properties of mixed matrix cation exchange membranes filled with activated carbon nanoparticles modified by chitosan was studied. Moreover, the scanning optical microscopy images showed uniform particles dispersion and uniform surface for the membranes. The membrane water content and ion exchange capacity of nanocomposite membranes were improved.  The membrane potential, selectivity and areal electrical resistance were enhanced initially and then decreased. Also, the selectivity of mixed matrix membrane was increased initially by increase in electrolyte concentration and then showed decreasing behaviour by more increase in electrolyte concentration. Moreover, obtained results exhibited more selectivity for the membranes at neutral condition in comparison with acidic or base regions. The areal electrical resistance of membranes was also decreased by increase in electrolyte concentration. Moreover, an increase in electrolyte pH initially caused that membrane areal electrical resistance enhanced however areal electrical resistance declined again at higher pH values. The ionic flux of prepared membrane showed an alternative trend when additive ratios were increased. Finally, the transfer properties of membranes showed that the modified membranes in this study were comparable with that of commercial ones.

The surface modification of polyvinylchloride-based heterogeneous cation exchange membranes was carried out using chitosan-co-polyaniline/graphene oxide nanocomposite layer for the application in electrodialysis process. The PANI/GO nanocomposites were prepared by in situ chemical oxidative polymerization of aniline in the presence of graphene oxide nanoplates. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), water content, flux and permeability, areal ionic resistance, water softening ability and fouling measurements were used to characterize the membrane. The FTIR analysis results and SEM images demonstrated successful formation of polyaniline on the graphene oxide nanoplates. The scanning electron microscope images of membranes also exhibited a uniform layer of chitosan-co-PANI/graphene oxide nanoplates on the membrane surface. The water content of modified membranes was higher than that of pristine membrane. The sodium flux and sodium permeability were improved about 20% by 0.1 %wt PANI/graphene oxide nanocomposite. The areal ionic resistance of modified membranes also showed a decreasing trend by utilizing composite nanoplates in the membrane matrix. The prepared membranes showed good ability for Ca and Mg removal from water. The removal efficiency of Ca and Mg by membrane containing 0.5 %wt PANI/graphene oxide composite nanoplates was, respectively, 61 and 79% during 15 min. Moreover, the pollutant and foulant formed on the membrane surface were totally removed by sonication technique. The modified membranes showed suitable electrochemical characteristics compared to membranes reported by other researchers and made by industries.

Polyvinylchloride (PVC) based heterogeneous cation exchange membranes were prepared by the solution casting technique. The effect of super activated carbon nanoparticles concentration as filler additive in membrane matrix on ionic transfer behaviors of the membrane was studied. SOM images showed uniform particles distribution and relatively uniform surfaces for the membranes. The membrane water content was improved initially by using of super activated carbon nanoparticles up to 0.5 %wt in the casting solution and then began to decrease by more increase of nanoparticles content ratios from 0.5 to 4 %wt. Utilizing of activated carbon nanoparticles in the casting solution also led to increase of water contact angle, membrane ion exchange capacity, fixed ionic concentration, membrane potential, transport number and membrane selectivity obviously.An Opposite trend was observed for the membrane electrical resistance. The sodium flux/permeability was also enhanced initially by increase of nanoparticles concentration up to 0.5 %wt and then decreased slightly by more increase of nanoparticles loading ratios from 0.5 to 1 %wt. The sodium flux was sharply enhanced again by more increase of nanoparticles concentration form 1 to 4 %wt. The membrane transport number and selectivity were increased initially by increase of electrolyte concentration and then showed decreasing trend. The membranes showed higher transport number and selectivity at neutral pH compared to other pH values. The ED results showed that dialytic rate of lead ions was increased by utilizing of super activated carbon nanoparticles in the membrane matrix.