Preparation And Desulfurization Performance Of ZIF-8/Polyethylene Glycol Hybrid Membranes

In recent years,serious smog has occurred in most urban areas,and air pollution has received widespread attention.One of the main reasons for the growing problem of air quality is the emission of automobile exhaust.The combustion of sulfides in gasoline produces SO_x,which causes air pollution after discharge.Removing sulfide from gasoline is the fundamental way to solve the problem.Pervaporation desulfurization is a new and efficient desulfurization method with low energy consumption and high desulfurization efficiency.Permeate flux and enrichment factor are the common criteria for evaluating membrane performance in most pervaporation desulfurization literatures,but these factors are susceptible to operating conditions such as temperature and pressure and do not truly reflect the pervaporation performance of the membranes.In this paper,the desulfurization performance of different materials were compared by permeability and selectivity,and the effects of modified materials and modification methods on the performances of membranes were studied.The results show that the polyethylene glycol?PEG?has good desulfurization performance.Therefore,the PEG is selected as the polymer matrix of the hybrid membrane for the next study.ZIF-8 particles have a higher adsorption selectivity for thiophene.In order to solve the problem of agglomeration and interface defects of traditional hybrid membranes,PEG@ZIF-8/PVDF nanoparticle composite membranes were prepared by layer-by-layer assembly.The membranes were analyzed and characterized by SEM,XPS,etc.The results show that the PEG@ZIF-8/PVDF membrane has a uniform and dense ZIF-8 layer,and the PEG layer has no obvious defects.The PEG layer,ZIF-8 layer and PVDF layer are tightly bonded.The effects of operating temperature and feed sulfur content on the desulfurization performance of PEG@ZIF-8/PVDF membrane were investigated systematically.The results showed that the PEG@ZIF-8/PVDF?#3?membrane had the highest permeation flux,reaching3.08 kg/?m²h?at 85°C.The PEG@ZIF-8/PVDF?#6?membrane had the highest enrichment factor.However,with an increase in the thickness of the particle layer,the membrane permeation flux decrease.The graphene oxide?GO?was introduced to solve the flux loss caused by the increase in the thickness of the particle layer.The composite particles and the composite membranes were characterized and analyzed by SEM,TEM,etc.The results showed that there was a dense and uniform ZIF-8 layer in the prepared PEG@GO-ZIF-8 membrane which GO was grown in situ first and ZIF-8 was grown in situ second.The pervaporation experiment showed that the permeate flux and the enrichment factor of the PEG@GO-ZIF-8 membrane were simultaneously increased.When the operating temperature was 85°C,the permeate flux was3.7 kg·m^-2·h^-11 and the enrichment factor was 7.9.Compared with pristine PEG membrane,these increased by 205%and 41%,respectively.The"trade off"effect was overcome.