Preparation And Desulfurization Performance Of Performance Of Metal Ion Modified PDMS Composite Membranes

Nowadays,many countries and regions have strictly controlled the organic sulfur content in gasoline because it can cause serious environmental hazards after burning,such as acid rain and haze,etc.China constitutes a large proportion of catalytic cracked gasoline which makes deep desulphurization an imminent issue.Membrane pervaporation desulfurization,as an emerging desulfurization technology,has attracted widespread attention due to its various advantages such as high efficiency and environmental protection.In this study,a variety of metal ion-modified PDMS desulfurization membranes were prepared by starting from the complexation between transition metal ions and organic sulfur and using polydimethylsiloxane as the base membrane.The effect of pervaporation performance and the role of metal ions in the transfer of thiophene across channe the were systematically studied.Selecting iminodiacetic acid as a chelating agent and introduced metal ions on the surface of PDMS membrane by chemical grafting,so PDMS-Cu,PDMS-Zn and PDMS-Mn were prepared for pervaporation desulfurization in this study.The characterization analysis of FTIR and XPS proved that metal ions were successfully loaded on the membrane surface and SEM showed that the metal ions were uniformly distributed on the membrane surface.The analysis of the metal ion-modified membrane by various characterization methods showed that the modified membrane have smaller free volume and higher swelling resistance,and its mechanical properties and thermal stability are also enhanced.The results of membrane performance test showed that as the temperature increases,the permeation flux and sulfur-rich factor of the PDMS-M membrane increases.This is because the empty d orbital of the metal ion accepts the lone pair electron of the thiophene sulfur atom to form?complex,which improves the pervaporation performance of the membrane.When the operating temperature of 75°C and feed liquid concentration of 200 ppm,the best separation effect of the three metal ions modified membranes achieved.In the meanwhile,the permeation flux of the three membranes were 2.08 kg/(m~2h),2.1 kg/(m~2h)and 2.12 kg/(m~2h)and sulfur-rich factors were 4.24,4.4 and 3.63,respectively.Subsequently,Ag,Cd,and Pb,which are strongly bound to sulfur,were selected as modified metals according to metal coordination theory,and?-mercaptopropyltrimethoxysilane(MPTMS)was selected as a complexing agent according to the rules of soft and hard bases to prepare PDMS-Ag,PDMS-Cd,PDMS-Pb membranes for pervaporation desulfurization.The characterization results showed that the modified one has good swelling resistance and thermal stability.The results of performance test showed that the soft acid metal-modified PDMS membrane has higher desulfurization capability.The permeation flux of the three metal ion-modified membranes were 2.12 kg/(m~2h),1.89 kg/(m~2h)and 1.5 kg/(m~2h)and the sulfur-rich factor were 5.6,4.4 and 4.9,respectively.