چكيده به لاتين
Due to the water scarcity in the world, the treatment of industrial wastewater and the water reuse to the cycle has become very important. Membrane filtration has expanded its application in the field of wastewater treatment in recent years. Based on research, it has been accepted that in membranes with good antibacterial and hydrophilic properties, the fouling is reduced and the treated water is of better quality. In the present study, poly ether sulfone/silver nanocomposite membranes were fabricated and evaluated in the membrane bioreactor system with the aim of improving the performance of poly ether sulfone membranes for wastewater treatment by NIPS method. In order to increase hydrophilicity and interaction between the polymer and the nanoparticles and enhance the antibacterial properties of silver nanoparticles, the surface modification process of nanoparticles was applied, due to which amine functional groups were substituted on the nanoparticles. In order to evaluate the modification quality of silver nanoparticles, Fourier transform infrared spectroscopy (FTIR) and field emission electron microscopy (FESEM) were used. In FTIR test, successful formation of amino groups on silver nanoparticles was observed. In order to characterize the fabricated membranes, phase separation behavior tests, pure water permeability, contact angle, mechanical strength, FESEM and antibacterial property test were used. The membranes were prepared on hollow fiber modules for further investigation. According to the results, it was observed that the modified membranes have a thicker outer layer compared to the neat sample, which increases the efficiency of the separation process. Modified membranes are more hydrophile due to the presence of silver nanoparticles and amino groups, and their antibacterial properties increase the ability to repell and terminate microbes and prevent the formation of microbial secretions on the membrane surface. Further studies showed that membrane samples containing 1.5 wt% of modified silver nanoparticles, with a pure water flux of 60 LMH, had the highest percentage of pollutants (about 97%) and the lowest total fouling (about 27%) compared to other samples; Flux recovery in this membrane sample was about 90%. The initial contact angle was also reduced from 83 degrees to 57 degrees. Further investigation on fouling parameters showed that with increasing the amount of nanoparticles, these membranes show a slight decrease in the water flux. Moreover, irreversible fouling in neat sample changed to reversible fouling in modified membranes. Also, the study of fouling models showed that the neat membrane has a cake-type fouling, and in the case of membranes with pure silver nanoparticles, since the type of contaminant was constant, changing the type of fouling to a standard state indicates the entry of contaminants into the membrane cavities. Further, using the modified nanoparticles provided excellent overlap in the cake-type fouling model indicating that the pore size was reduced; nanocomposite membranes with modified silver nanoparticles have been very successful in removing contaminants and preventing their entrance into the membrane porous media.
