Research On The Pollution Analysis, Appraising And Adsorption Catalysis Of Volatile Organic Compounds In Car

Volatile Organic Compounds (VOC) are one of the most important pollutants of Automotive Indoor Air Quality (AIAQ) and the primary factor on "Automobile Driving Syndrome, New Car Smell" because of their high toxicity and harm. So, how to improve the AIAQ and to control the in-car VOC pollution is to be imminent. In this research, the investigation of in-car air pollution in Changsha and the VOC mass concentrations in interior air of125vehicles were obtained.The mean levels of airborne benzene, toluene, ethylbenzene, xylenes, p/m-xylene, o-xylene, styrene, butyl acetate, undecane and TVOC in cars were83.6,215.9,75.6,184.3,117.6,66.7,25.0,29.1,62.9and1459.6μg/m3, respectively, through the sample investigation. The rates of cars tested where the interior concentrations exceeded the limit levels of Chinese Indoor Air Quality Standard were14.4%for benzene,65.6%for toluene,37.6%for xylenes and92.0%for TVOC. The VOC levels increased when in-car temperature, exhaust volume or relative humidity increased, and decreased when car age, interior volume or travel distance rose. The VOC pollution was higher in leather trims cars than in non-leather trims ones, in air-conditioned cars than in non-air-conditioned ones, in gas cars than in diesel oil ones, in saloon cars than in taxis or buses, and changed with the differences of ventilation modes, vehicular grades, driving speed, sampling space or interior airflow speed. Smoking caused in-car VOC mass concentrations to increase greatly.Through stepwise of multiple linear regression analysis, the optimal regression equations between VOC levels and13influencing factors were drawn, for example, Ybenzene=16.8+1.8X3+0.46X4-1.29X6+6.46X7; with principal component analysis, the13factors had three principal components and the percentage of total variance achieved75.3%; through cluster analysis, the strongest subcluster included the car age and interior temperature. In conclusion, car age (X6) is the most important factors influencing the in-car VOC concentrations, followed by interior temperature (X3). With the curve estimation, the cubic equation of a variable is between in-car VOC levels and car age such as Ytoluene=332.87-13.27X6+0.41(X6)2-0.01(X6)3, and the nature logarithm function is between in-car VOC concentrations and temperature such as Yxylenes=-695.81+262.27ln(X3).The pollution loss rate of AIAQ increased when the interior temperature, the same VOC level or the exceeding standard times of different VOC levels increased, and decreased when the car age rose. As for the average rank of AIAQ, the sampled cars were the light pollution; the heavy, middling, light, clean and no pollution car was0.0%,16.0%,66.4%,16.0%and1.6%, respectively. The mi and bi are constant, and is5.89and32.45in turn in the equation of pollution loss rate.With the health risk assessment, the non-carcinogenic danger coefficient (HI) of in-car VOC pollution by far is lower than the datum value (1), and does not harm the personnel; the benzene carcinogenic risk (Rz) to drivers is dangerous and the mean value is1.21×10-4. To the man driver, the Rz or HI of VOC is biggest, followed by that of woman driver, man passenger and woman passenger because the feminine mean lifetime excels in the male, but the breathing rate is lower than the masculine result and the exposure time of driver is longer than that of passenger. Through calculating, CD=1-40×AL×BE÷EF÷ET÷IR÷LT and in the equation, the CD, AL, BE, EF, ET, IR and LT is the dangerous levels, lifetime, body weights, exposure frequency, exposure time, inhalation rate and exposure duration, respectively. When the Rz is1×10-4, the Co for man passengers, woman passengers, man drivers and woman drivers is450,470,67.5and70.4μg/m3in turn.Through the vibration and impregnation method, the compound material of Pt/TiO2/ACF was synthesized. When the platinum quantity is1.0%, the effect is best; to lengthen the reaction time or increase used amount, the purification efficiency is higher. The elimination rate of in-car benzene, toluene, ethylbenzene, xylenes, styrene and TVOC density respectively is76.1%,75.5%,74.7%,75.9%,76.2%and76.3%with sunlight illumination; the purification efficiency of the material to in-car VOC has formed the positive cycle of adsorption-catalysis-adsorption-catalysis. The Pt deposition enhanced the TiO2photochemical catalysis and strengthened the purification efficiency of the compound materials to in-car VOC pollution.