Exploration Of Quercus Variabilis Cork’s Chemical Impurity Removal Technique

In order to improve the utilization of domestic quercus variabilis cork raw materials and theperformance and quality of cork products, The paper explores chemical impurity removal technique basedon the domestic cork produced in Qinling mountain. First of all, microscopic structure observation andchemical composition analysis have been implemented, which can provide theoretical basis to the chemicalimpurity removal. Secondly, explores chemical method using common acid solution to remove impurity.Thirdly, observes the microscopic structure and analyses the chemical composition of the acid treated cork,analyses the effect of impurity removal on the properties of cork. Main research conclusion is as follows:Macroscopic observation of sclereid can see hard white granule sporadic distributed or arranged in airregular strip. Lenticel tissues filled with brown powder,which arrange loosely, hard and brittle. Sclereidand lenticel mainly exisit in primary cork, less in secondary cork.. Scanning electron microscopy (SEM) onthe sclereid can see the sclereid’s cell is hexagon,the cell wall is thick and plicated,some have pit andprotrusion and some has no cell cavity. A lot of inclusion can be seen in the cell walls which arecrystal.Lenticel tissues’s cell is elliptic,smaller than cork cells, arranges regularly and bead in diameter anda transverse cross section. The cell wall is incrassated, has round cell cavity. Cell extrudes deformationwhere the cork cell and impurity cell contect.The primary cork are different with sclereid and lenticel in chemical component: sclereid and lenticelcontent more suberin, less cellulose and ash content han cork.Other chemical content such as extract, acidinsoluble lignin are not obvious. Quercus variabilis cork impurity could not soluble in water, alcohols,ketones, ethers and so on, can be completely corrosion by acid and alkali, can react with common strongacid dilute solution. Orthogonal experiment preliminarily determines chemical process of impurity removal:5.82mol/L HCL and6.12mol/LH2SO4according to the volume ratio4:3mixed,soak thespecimen,60℃,test time is20hours. After processing, cork specimen sample average drop of0.018g/cm3density, hardness decreased8on average. The specimen’s color after processing experience100hours ofuv resistant climate chamber changes2.06when the untreated specimen color change2.59.Visual observation of specimen, the color of sclereid change into brown and there’re obvious gapjunction between the impurity and cork cell. Observation with Scanning electron microscopy (SEM) cansee visible gap between cork and impurity, impurity also has obvious gaps between cells.The cork cellsaround impurity have no obvious changes,so the impurity removal technic did not significantly influencethe cork material. Analysis of the cork chemical composition after processing is as follows: cork after processing haveless suberin, more Methylene chloride and ethanol extract than cork without processing.Throughcalculation of difference found that total chemical composition content is not obvious different between thecork material after processing and without processing.Thus the impurity removal technic has no significantimpact on cork materical.