| Cigarette smoke contains many kinds of harmful substances,such as NO,which is harmful to human body through disrupting the balance between oxidation and antioxidation and accelerating the processes of oxidation and peroxidation.So it is necessary to remove it.Adding propriate additives in cigarette filter can effectively reduce the concentration of NO in cigarette mainstream smoke.At present,selective adsorption and selective catalytic reduction are the main methods for removing NO from cigarette smoke,which often use precious metal as active component of catalytic reducing agent,thus the high cost of filter tip additives reported makes it impossible to apply in industry.The purpose of this paper is to find a poosible new filter tip additive that pocesses advantages of low cost,as well as high NO removal effciency.In this paper,ACF modified by HNO3 is used as support.Cu and Ce are selected as active component.Additive is prepared by equivalent volume impregnation.NO removing efficiency is evaluated on a fixed-bed reactor.The preparation methods of filter additives are optimized through orthogonal tests with the index of NO removal rate and the optimum conditions are determined as follows:heating rate is 10?ˇmin-1,calcination time is 3 h and the active loading of 23%Cu0-5%Ce02.The highset removal rate of NO in the first 10 minutes is 69.47%and average removal rate within 40 minutes is 66.61%at the conditions:loading quantity is 0.005g,T is 40?,NO concentration is 500 ppm and the gas flow is 60mLˇmin-1.The additive also has a good performance on the removal of formaldehyde,naphthalene and SO2.Characterizations of the additive were done by using XRD,BET and IR technology.The XRD analysis shows that,for filter tip additive prepared under the condition of 550?,Ce exists in the form of Ce02 with the cubic fluorite structure,and CuO is in amorphous state.Combining the study on NO removal,it can be concluded that the dispersion of active components has obvious effect on NO removal:the higher dispersion the better removal efficiency.The BET analysis concludes that the specific surface area of ACF decreases after nitric acid pretreatment,which means the pretreatment can expand the pore,and the appropriate pore-expanding can offset the pore blockage caused by active loading,which is useful to improve the NO removal efficiency.The IR analysis of the fresh and used additive show that there are peaks which represent the functional groups such as(NO)?+,(NO)2?-and N0-3 appeared in the used additive.It is helpful to illustrate the conclusion that the NO is removed mainly through the interaction of catalytic oxidation and chemical adsorption,meanwhile the opinion is further affirmed by the fact that 02 added in the smoke can improve NO removal efficiency.This method has some advantages,such as low price,simple preparation procedure,high efficiency of NO removal as well as other harmful ingredients in smoke,which is suitable for industrial applicantions. |
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