| The VOCs produced by the pharmaceutical industry not only pollute the atmospheric environment,but also seriously endanger people’s health,which are called“the front door pharmaceutical treatment and the back door sewage treatment”.The VOCs in the pharmaceutical industry are difficult to degrade compared with those of other industries which is toxic.A few researches about the VOCs were not enough.Therefore,dealing with VOCs produced by the pharmaceutical industry has become an important research direction.Two kinds of VOCs produced by a pharmaceutical company in Jiangsu Province were studied in this dissertation.The VOCs were purified by chemical absorption method,photocatalytic oxidation technology and chemical absorption photocatalytic oxidation technique.The results are as follows.The chemical absorption method was used to investigate the purification effects of three kinds of absorbents（benzyl alcohol,ethanol,n-propanol）and four influencing factors（intake concentration,liquid-gas ratio,residence time and absorption liquid purity）of the two VOCs.The results showed that the best absorbent was n-propanol from the aspects of economic efficiency and purification effect.The removal rates of dipropyl sulfide and n-propyl mercaptan were 85.68%and 86.96%,respectively.The order of impact of thioether purification efficiency in descending order was:liquid-gas ratio,residence time,intake concentration,absorbent purity;the order of influence on the purification efficiency of n-propyl mercaptan is:liquid-gas ratio>residence time>intake concentration which had the same effect as the absorbent purity.Under the condition of inlet air concentration of 2000mg/m3,with the liquid-gas ratio of 80L/m3,4.0s of the residence time,and 98%purity of the absorption liquid,n-propanol absorbent had the best removal effect on dipropyl sulfide and n-propyl mercaptan.The removal rates were 90.28%and 91.96%,respectively.Three kinds of TiO2modification methods(Fe3+doping modification,Zn2+doping modification and semiconductor composite TiO2-Zn O modification),two kinds of load carriers（porous metal plate and ceramic honeycomb plate）were investigated by photocatalytic oxidation technology.The purification effects of the three influencing factors on the two VOCs are initial concentration,residence time and relative humidity of them.The results showed that when the initial concentration of VOCs was 500mg/m3,the relative humidity was 40%,with the residence time of3.5s,when the photocatalyst was Fe3+doped TiO2and the supported carrier was ceramic honeycomb board,could we get the best removal effect of the propyl thioether and n-propyl mercaptan,and the removal rates were 52.41%and 58.36%,respectively.The order of influence of the three influencing factors on the purification efficiency of dipropyl sulfide and n-propyl mercaptan was:residence time>relative humidity>initial concentration of VOCs.Under the condition of initial concentration of VOCs of 400mg/m3,residence time of 6.0s and relative humidity of 50%,Fe3+modified TiO2has the best removal effect on dipropyl sulfide and n-propyl mercaptan,and the removal rates are 72.09%and 75.14%,respectively.The laboratory experiments and field tests were carried out by chemical absorption method and photocatalytic oxidation technology.The results showed that the inlet flow rate was 11.8m3/h,the purity of the absorption liquid was 98%,the liquid-gas ratio was 80L/m3,and the relative humidity was 50%,the running time of30min,in the field test,the removal rate of dipropyl sulfide and n-propyl mercaptan were 87.25%and 89.50%respectively;In laboratory tests,the removal of dipropyl sulfide and n-propyl mercaptan,the rates are 97.66%and 98.96%,respectively.The actual on-site exhaust gas is more complex than the laboratory simulated exhaust gas composition,which is the main reason for the decrease in removal rate. |
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