Study Of Reducing Carbonyl Compounds And Nitric Oxide In Cigarette Mainstream Smoke

Smoking is harmful to health. Volatile carbonyl compounds and nitrogen oxides are two major types of harmful components in cigarette mainstream smoke. Reducing such harmful components has significant value to enhance safety of cigarette. This paper studied the mechanism of the formation of carbonyl compounds, and discussed the formation rule and influencing factors. We have used some low-cost materials such as the natural renewable resources and the transition metals to reduce carbonyl compounds and nitrogen oxides in cigarette mainstream smoke. The research has important academic and practical significance in the development of tobacco science and tobacco industry.The formation mechanism of the carbonyl compounds in cigarette is researched through theory and experiments.The thermodynamic and kinetic properties of bond dissociation reaction and transiton state reaction was studied using DFT theory in B3LYP/6-31G. Bond dissociation energe and activate energe of transtite state were calculated.Major pyrolysis routes were determined by the theoretical calculation.The mechanism can be used to predict pyrolysis route and major products of 1,2-propylene glycol and 1,3-propylene glycol.The results indicated that the active energy of the dehydration reaction is between 53.64kcal/mol and 64.98kcal/mol.The primary products will formate acrolein,formaldehyde and acetaldehyde.The activation energy of 1,2-propylene glycol dehydration reaction is between 60 kcal/mol and 70 kcal/mol, The main pyrolysis products of 1,2-propylene glycol are propionaldehyde, acetone and acetaldehyde, the yield of propionaldehyde is far higher than others.The active energe of 1,3-propylene glycol is between 50 kcal/mol and 60 kcal/mol. The major procucts of 1,3-propylene glycol are formaldehyde, acetaldehyde and acrolein. The experiment datas showed highly agreement with theoretical derivation.The effects of temperature,oxygen concertration and nitrogen flow on the yield of volatile carbonyl compounds from carbohydrate, humectants and different tobacco type were researched by orthogonal experiments L9(33). The results as followed: Nitrogen flow remarkably affected the yield of formaldehyde; Temperature is the main factor of formatting other volatile carbonyl compounds, while oxygen concentration showed a little effects on the yield of the carbonyl compounds.Formaldehyde, acetaldehyde, acetone and acrolein are produced in high yield during the pyrolysis of glucose, fructose, sucrose and starch, which have the similar low of producing carbonyl compounds through pyrolysis. In the four kinds of humectants, propylene glycol is like to produce much more acetone and propionaldehyde than glecerol, xylitol and sorbitol. Yield of formaldehyde, acrolein and crotonaldehyde, produced by glycerol pyrolysis, are the highest. When pyrolyzed at 600℃, xylitol generated the most methyl ethyl ketone. While sorbitol can produce the most butyraldehyde in the case of low oxygen concentration and nitrogen flow rate.Temperature significantly affected the generation of carbonyl compounds of the three kinds of tobacco. The yield of formaldehyde produced by oriental tobacco was far higher than others when pyrolyzed at 600℃.Furthermore, all kinds of tobacco that were pyrolyzed at 800℃produced little carbonyl compounds.Renewable biomacromolecular resources-chitosan and the transition metals were selected to prepare complex and nano-metal complex oxide through complex and co-precipation method.The preparation structure were charactered.The effect of preparation on carbonyl compounds and nitrogen oxide in mainstream smoke and the structure-activity relationship were studied.The results indicated that the optimized preparation condition of copper-chitosan complex is as followed: pH 4.8, temperature 25℃, molar ratio of chitosan to copper sulfate 10:4, time 30min. In this case,amino or amide groups in chitosan complexed copper ion. There is an important relationship between the adsorption properties of carbonyl compounds on chitosan-copper(Ⅱ) complex and the polarity and molecular weight of carbonyl compounds. The adsorption capacity decreased rapidly with the carbon chain increasing and polarity reducing. The adsorption rate of formaldehyde is up to 53%, nevertheless, only 12% for four carbon carbonyl compounds. Compared aldehydes with its isomer ketones, the result indicated the adsorption of the complex to ketones was stronger than aldehydes, In addition, the complex showed the strongest adsorption capacity to the unsaturated carbonyl compounds. Besides carbonyl compounds, the copper-chitosan complex can adsorb phenol and HCN to certain extent, but has no effect on removing the CO, nicotine and tar in the mainstream smoke.The optimum preparation condition of Copper iron composite oxides can be fixed as follows: molar ratio of copper to iron 1:5,pH 9.0,ageing time 90min,calcination temperature 300℃and calcinations time 5h;the optimal preparation condition condition of CuO/Co3O4 catalysts are as followed: molar ratios of copper to cobalt 1:5,volume of NaOH 15ml,ageing time 5h,calcinated at 200℃for 3h.Copper iron and copper cobalt complex oxides can catalysis NO in cigarette mainstream smoke to formate non-harmful N2 at low temperature.When added in the cigarette, NO in the mainstream smoke can be significantly removed in the additive amount of 2%.Comparison with CuO/Fe2O3 complex,CuO/Co3O4 showed higher catalytic activity. When addition amount to 5%,NO can be converted by 50%。This article explored the mechanism of carbonyl compounds forming in cigarette smoke, the forming pattern and influence factors. We have determined the main precursors of carbonyl compounds in the mainstream smoke, as well as major influence factors. We also established the technique to utilize chitosan-Cu(II) complex and two nano-metal complex oxides to reduce harmful carbonyl compounds and NO in the cigarette smoke. This research is creative and important in reducing other harmful ingredients in mainstream smoke.