Research On Efficient Utilization Technology Of Special Plant Material-wastes

It is one of the important ways to comprehensive utilization of special plant resources,which can save energy, protect the environment and increase agricultural income currently.Tobacco plant is one important special economic plant in our country, while in the process ofits using producing a large amount of waste. Reconstituted tobacco is the main method torealize high-efficient and logical utilization of tobacco wastes. Using reconstituted tobaccopaper making-method has quickly become the core technology of comprehensive utilizationtobacco waste. This paper mainly studied for paper-making reconstituted tobacco extractiontechnology, rheological properties of coatings and pyrolysis kinetics, in order to improve theefficient use of tobacco waste to provide theoretical support.Tobacco stems and leaves were extracted by solvent of water, and the effects of extractedtime, extracted temperature and solid/liquid ratio on extraction rate were evaluated. Theresults of orthogonal experimental analysis indicated that, extracted time was the mostimportant factor affecting tobacco stem impregnation extraction process, while extractedtemperature was the most important factor affecting tobacco leaves impregnation extractionprocess. Combining orthogonal experimental and single factor experimental analysis, theoptimum impregnation extraction processes for tobacco stems and leaves were obtained. Fortobacco stems, the best condition was extracted at60oC for100min at a solid/liquid ratio of1:7. For tobacco leaves, the best condition was extracted at70oC for60min at a solid/liquidratio of1:10. Using the optimum extraction process, the dissolution rate of water-solublesugars, total plant alkaloid, total nitrogen element and choloride element in the tobacco stemwas50.60%,52.46%,19.86%and64.32%, respectively. And the dissolution rate ofwater-soluble sugars, total plant alkaloid, total nitrogen element and choloride element in thetobacco leaves was73.06%,64.57%,7.89%and72.02%, respectively.By adding three kinds of rheological agents, carboxymethyl cellulose (CMC), guar gum(GG-50), and cationic guar gum (CGG) in the coatings, coatings showed a good rheology, andhad a good shearing thinning phenomenon. The adding of adhesives had a great impact on thephysical properties of reconstituted tobacco. As the adhesives dosage increased, thereconstituted tobacco had decreased the bulk, air permeability and filling ability, but hadincreased the tensile strength and tear index. In addition, the surface permeability, wettabilitydecreased, while hygroscopicity was affected limitedly. Flue gas tar, total particulate matterand carbon monoxide content showed a rising trend, and the number of puffs had a decreasing trend, but almost no change were observed in the amount of nicotine in the flue gas. When theadhesive in an amount of0.1%, the viscosity of the coating is between100mpa·s and115mpa·s, after coating the reconstituted tobacco had a better surface structure and physicalproperties.Adding combustion improvers into the coating improved the characteristics ofreconstituted tobacco and reduced the tar and CO emission in the main smoke. By addingpotassium citrate and sodium citrate in the coatings, the pH value of the coating was slightlyincreased due to the neutralization of a small amount of organic acid in the coating, while theviscosity of the coating was relatively stable. Adding combustion improvers had a greatinfluence on accelerant flue gas content of the reconstituted tobacco. Potassium citrate andsodium citrate improved the combustion resistance of the reconstituted tobacco, and reducedthe emission of harmful substances in the smoke component. Potassium citrate was better thansodium citrate reducing the tar and CO emission of the flue gas and lowering the number ofpuffs. Therefore, adjusting the proportion of potassium citrate and sodium citrate was of greatinterests when manufacturing the reconstituted tobacco with certain tar and CO emission.When the combustion improver was only potassium citrate, in the flue gas the tar was6.79mg,and the CO was15.7mg. By adding oxygenated potassium salt (K) to the reconstitutedtobacco, the tar and CO contents in the flue gas were significantly reduced, primarily due toits lower decomposition temperature. During decomposition heat was released, and oxygenwas released at the same time, that improved the combustion performance of the reconstitutedtobacco and reduced the tar and CO generated.By adding calcium carbonate (PCC) to the coating, the pH increased slightly, when theamount of added PCC exceeded10%, the viscosity of the coating had a decreasing trend. Theamount of PCC added should be controlled at about10%, which can effectively guaranteePCC particles and the tobacco impregnating solution to form a stable three-dimensionalsuspension system. The adding of PCC effectively improved the hygroscopic property of thereconstituted tobacco. With the amount of PCC increased, the hygroscopicity of thereconstituted tobacco reduced, especially when the relative humidity fell below80%. AddingPCC improved the storage properties of the reconstituted tobacco and significantly reducedthe tar and total particulate matter in the flue gas, but had less impact on the emission of CO.The TGA and DTG curve analysis of reconstituted tobacco with combustion agent addedindicated that the pyrolysis of reconstituted tobacco included three stages: dehydration,pre-decomposition stage, rapid decomposition stage and residual decomposition stage. Themodel fitting results of the pyrolysis of reconstituted tobacco with combustion improvers added showed that the proportion of sodium citrate and potassium citrate in the combustionagent had a great impact on the thermal decomposition activation energy value(E), anddiffusion reaction D1model obtained the highest fitting correlation coefficient in the threefitting temperature ranges (120~200oC,200~280oC,280~400oC). By increasing the amount ofoxygenated potassium salt in the combustion agent, the activation energy E value was almostno change in the range of120~200oC, and the pyrolysis reaction fitting model was thediffusion reaction D1model; in the range of200~280oC, the pyrolysis of oxygenatedpotassium salts during that temperature ranges significantly reduced the pyrolysis activationenergy of reconstituted tobacco, and the pyrolysis reaction fitting model was the diffusionreaction D1model. Within the range of280~400oC, the pyrolysis reaction of the tobaccosheet showed significant differences, due to the fast pyrolysis of the oxygenated potassiumsalts and the release of oxygen affecting the sheet component pyrolysis reactions process, andthe pyrolysis reaction fitting model was the diffusion reaction F2model.The addition of calcium carbonate (PCC) had a great impact on the pyrolysis ofreconstituted tobacco. When the PCC amount was4%, in the tree fitting temperatureranges(120~200oC,200~280oC,280~400oC), D1model was the main model for the pyrolysisof reconstituted tobacco with a higher linear correlation coefficient; when the amount ofPCC was8%, D1model was the main model for the pyrolysis of reconstituted tobacco at thetemperature ranges of120~200oC and200~280oC, but between280~400oC, single model fitlinear correlation coefficient was less than0.90; When the PCC amount was12%, linearcorrelation curve could not be obtained under the tree fitting temperature ranges. This ismainly due to the high pyrolysis temperature of PCC. Within the fitting temperature ranges,PCC had almost no weight loss causing the difficulty of fitting the reconstituted tobaccopyrolysis model with the ordinary biomass pyrolysis models.