Study On The Preparation Of Tobacco Stem-based Activated Carbon And Its Adsorption In Cigarette Smoke

Activated carbon is a widely used porous material with a wide range of raw materials,and most of the plant materials can be used to prepare activated carbon.Tobacco stems are a by-product of the tobacco industry.A large number of tobacco stems are discarded or incinerated each year,both wasting resources and causing environmental pollution.Reduction of harmful components is one of the eternal themes of the tobacco industry.However,cigarette smoke aerosol is a complex system,the adsorption of single component cannot meet the process.For this reason,the activated carbon can be prepared from waste tobacco stems.Activated carbons were used as a filter additive,the adsorption performance was analyzed from the perspective of various components.The main research contents and results are as follows:1.Activated carbons were prepared by zinc chloride activation and phosphoric acid activation by using tobacco stems as raw material,activator mass fraction,activation temperature and activation time were chosen as the three main factors.Single factor experiment was designed to investigate the structural properties of activated carbons under different levels.Factor order of influence and the interactions among the main factors were analyzed by Minitab software.The results show that the specific surface area of activated carbons prepared by zinc chloride activation were more than 1000m²/g,and the specific surface area of activated carbons prepared by phosphoric acid activation were up to 866m2/g.With surface area as index,the activation effect of zinc chloride was better than that of phosphoric acid activation.The pore structure adjustment of the activated carbons can be achieved by changing the amount of the activator for zinc chloride method.2.Microwave was used to expand the loose porous structure of tobacco stems and investigating the effect of water content,microwave power and expansion time of expansion rate for tobacco stems.Activated carbons were prepared by using expanded stems as raw material and zinc chloride as activator.The difference in specific surface area of activated carbons by comparing expanded stems under different conditions were compared.The results show that the specific surface area of activated carbons was related to the preparation conditions of the expanded stems,and the relationship with the expansion ratio are small.Excessive moisture content,expansion power and expansion time are not conducive to the preparation of activated carbon.3.Different structures activated carbons were used as filter additives to study the adsorption effects for seven main harmful substances in mainstream smoke.The results show that the adsorption structure of the seven harmful components were quite different.The highest reduction rates of activated carbons on B[a]P,NNK,HCN,NH3,crotonaldehyde,phenol and CO were 61%,55%,20%,47%,55%,69%and 37%.4.The activated carbons were functionalized with lysine and metal nitrates(Fe²⁺,Al³⁺,Mg²⁺,Cu²⁺and Co²⁺),and the basic groups and metal ions were supported on the activated carbons.The functionalized activated carbons were used as a filter additive.The results show that the functionalized activated carbons improved adsorption capacity greatly compared with unmodified activated carbons,the adsorption effect of phenol and HCN are the best than others,and the adsorption reduction rate were over 50%.5.Taking the o-toluidine and phenol in cigarette smoke as the targets,the coadsorption behavior were studied in aqueous solution,and the effects of temperature,time and pH on adsorption were investigated.The results show that the adsorption of o-toluidine and phenol by activated carbons belong to exothermic release.The pseudo second and Freundlich models can better describe the adsorption process of activated carbons.The optimum adsorption of o-toluidine and phenol could be observed when the pH was 7-8 and 6-7 respectively.