Study On The Environmental Behavior Of Accelerators And Antioxidants In Automobile Tires

At present,there are few studies on the level and release behavior of organic additives in automotive tires.Most of the results are based on samples of the wild,new automobile tires,or used automobile tires,respectively.Therefore,It is difficult to understand the difference of organic additives between new and old tyres and their contribution to the environment.T his paper studies the automobile tires which have large market share,in order to understand the concentration level and use of organic additives in automobile tires.And through the"particle–water–adsorbent"desorption device,changed the immersion medium?RO water and sea water?,the desorption of organic additives in two aquatic environments was studied.The effects of different particle sizes on the inhibition ability of organic additives for automobile tires were further analyzed,and the effects of organic additives on the environment were investigated by changing the temperature of desorption device.What's more,looking for a compound that is stable in the environment for a long time to indicate the transport of tyres in the environment.In this paper,the concentrations of accelerators,benzothiazoles?BTs?and antioxidants in new automobile tires of nine different brands and six used automobile tires collected from a fishing row in a bay are compared and analyzed.The result shows that there is no certain correlation between the concentrations of organic additives in automobile tires and the brands of tyres.The concentrations of accelerators were from 5.3 to 12000?g g^-1,benzothiazoles were from 90 to 270?g g^-1 and antioxidants were from 3500 to 24000?g g^-1 in nine new tires.While the concentrations of accelerators were from 0.36 to 6.0?g g^-1,benzothiazoles were from 6.4 to26?g g^-1 and two kinds of antioxidants were from 0.11 to 2.6?g g^-1 in six used tires.The concentrative level of organic additives in new and used tyres is quite different.Antioxidants are major organic additives in new tires,while benzothiazoles are the main in old tires,indicating that antioxidants are released more easily than benzothiazoles and the organic additives will decrease with the increase of used time of tires.The concentrations of accelerator CBS and accelerator DZ were from 0.0034 to 5.9?g g^-1 and 0.0046 to 7.5?g g^-1 respectively.They are mainly detected vulcanization accelerators in these nine tyres.On the contrary,accelerator NOBS and accelerator TBSI were not detected.The second derivative spectra of Fourier Transform Infrared Spectrometer was used to identify the rubber types of nine new automobile tires in this experiment quickly.It was found that eight of them were styrene–butadiene copolymer?SBR?and only one was synthetic cis–polyisoprene or cis–polybutadiene.In addition,the studies on the release of organic additives from automobile tyres particles in RO water and sea water have shown that the leaching rate?from 0%to 100%in 37 days?of organic additives in automobile tires is independent of the tire brands in aquatic environments?p>0.05?,but it is related to the octanol–water partition coefficient(log K_ow)of the compounds themselves.The increase of temperature?from 26 ^oC to 37 ^oC?can promote the release of organic chemicals in tyres particles,but the changes of particle size?750–150?m?have no significant effect on the imprison ability of organic additives.Compared with RO water,the leaching rate of analytes decreases in seawater,so the release of organic additives from automobile tires in sea water is a relatively slow process.A single chemical or groups of chemical substances consisting of isotopes,structures or molecular distributions specific to a particular source is defined as molecular markers that can be used as source indicators to provide a clear indication of a source of contamination.NCBA is the impurity of CBS which is widely used in the production of automobile tires.Its mass is basically conserved and there is no obvious degradation and transformation after tyres particles soaked in RO water and sea water for 37 days.NCBA is the most suitable traffic tracers result from stability,universal use in automobile tires and source specificity.