Arash Khosravi

In recent decades, desalinization of water through the process of membrane filtration, as a membrane heating process compatible with the environment and effective for desalination of water with a high level of salt compared to other traditional separation methods, has received attention is set. In the present research, the behaviour of Polyvinylidene fluoride (PVDF) hollow fiber membrane in the desalination of 3.5 wt% sodium chloride by using the direct contact membrane distillation system has been studied. The main aim of the research is to improve the performance of the process by modifying the membrane surface by Polydimethylsiloxane (PDMS) polymer solution containing different percentages of Polyhedral Oligomeric Silsesquioxane (POSS) nanoparticles. Finally, the synergistic effect of Fumed Silica (FS) nanoparticle on the optimal state of the modified membranes was investigated. Finally, the synergistic effect of FS nanoparticle on the optimal state of the modified membranes was investigated. Pure PVDF membrane was synthesized as a base membrane by phase inversion method and the membrane surface was modified using dip coating method. Using SEM, FESEM, EDS-MAP, AFM, Ca and LEP characterization and structural evaluation tests, the morphology, topology and hydrophobicity of the base membrane and modified membranes were analyzed and evaluated. The modification of the surface led to an increase in the contact angle of the base membrane from 77.3° to 140° and the LEP value increased to more than 8 bar. By ensuring the correctness of the characterization tests of the prepared membranes, the functional tests of the membranes were checked. Flux measurement, salt removal and long-term stability of the membranes were performed by the DCMD system. The obtained results indicate that, as a result of surface modification and reduction of membrane porosity, the basic membrane flux decreased from 3.5 kg/(m2.h) to 1.1 kg/(m2.h) and all membranes showed a salt removal rate above 99