Quantitative Analysis Of Thiophene Sulfur In Gasoline Using SERS With Nano-surface Silver Substrate

The burning of sulfide in gasoline not only affects the normal operation of locomotive but also causes tremendous hazards to environment.The detection of sulfur content in gasoline becomes urgent important,with more and more strict legal control over sulfur content in the world.Because of the sulfur in gasoline was mainly exist in form of thiophene and convenience,non-destruction and greenness of surface enhanced Raman spectroscopy(SERS)technology,a new method analyzing sulfur content with SERS technology was presented in the paper.The prepration conditions were optimized,and quantitative relation between inspection standard and sulfur content was utilized to further outcomes in gasoline.Potentiostatic oxidation-reduction method was selected to prepare nano-silver substrate,and in numerous factors including KCl solution concentration,redox potential and reaction time,KCl solution concentration(The optimal concentration was 0.10 mol·L-1)was the key factor that affect the preparation of nano-surface silver substrate.The adjacent equilibrium potential and longer electrolytic time benefited the formation of regular nano-substrate which behaved good enhancement effect.Bromine ion being added to electrolyte had some advantages for the preparation of SERS active substrate.When electrolyte was 0.10 mol·L-1KCl solution including 3×10-4 mol·L-1KBr,the terrific enhancement effect was acquired that relative area intensification factor was equal to 81746,and silver nanoparticles of the substrate was evenly.The adjacent equilibrium oxidation-reduction potential(0.15 V / 0.04V(vs.SCE))was found out via experiments,and under the potential,when electrolyte was 0.10 mol·L-1KCl solution including 3.0×10-4 mol·L-1KBr and reaction time was 100 s,good enhancement effect was obtained that relative intensity factor was 4859 and relative area factor was 53.Although enhancement effect was weakened,stability was greatly improved after several tests,owing to equilibrium potential could benefit mild reaction and higher stability of substrate.At the same time,silver nanoparticles of the substrate could be more uniform with repeated redox reaction.Through the determination of Raman spectra of simulated gasoline containing different sulfur content with active silver substrate,the quantitative relation between relative peak area of the band 1363cm-1 and sulfur content was acquired,y=-1.514×10-4x2+0.0381x-0.0788,and the scope of correlation was 5~90 mg·kg-1 and R2=0.9932.Thiophene sulfur content of 93# and 97# gasoline were 5.81 mg·kg-1 and 6.20 mg·kg-1 respectively that was determined using this method.Meanwhile,the average recovery was 101.17% and RSD was 4.12%,which validated accuracy of this method and laid the foundation for determination of total surfur content in gasoline.The detection of thiophene sulfur content in thiophene-n-hexane simulated gasoline was carried out using surface enhanced Raman spectroscopy combined with nano-silver substrate in this thesis,and through optimizing the substrate,thiophene sulfur content was analyzed in real gasoline and the foundation was laid for determination of total surfur content in gasoline.