Develop Their Physical And Chemical Properties Of The Larch Tannin Extract Residue Lignin Sulfonate

The barks of Larch once extracted were modified by alkaline sulfite and lignosulfonate was obtained in this reaction. The product can be used as water reducer in concrete. We can find an effective method to use the bark. The chemical compositions of the bark and the process conditions of the sulfonation reaction were investigated. Studies on the physical and chemical properties and chemical structure characteristics of the lignosulfonate have been conducted. The conclusions are drawn as follows, 1,The author systematically determined the chemical composition of the bark and the mass percentage of lignin, tannin, phlobaphen, phenolic acid. It was known from the experimental results that the bark contained a lot of phenolic compounds, and the content of lignin in bark was higher than the content in the wood while the content of carbohydrate in bark was far lower than that of in the wood. 2,The factors which influenced the results of reaction were investigated to get the optimum reaction conditions. Meanwhile, the effect of formaldehyde on cooking was discussed. 3,The optimum reaction conditions are: temperature 170℃, the total alkaline charge X7% (the dosage of sulfite based on it is Y2% ), the ratio of dry material to liquid 1:5, the keeping time 5hr. At the ideal condition, the yield of the product is over 70%. While we add the lignosulfonate into concrete, clean solution's fluidity will improve greatly and reach 210mm. 4,Compared the bark sodium lignosulfonate with the wood calcium lignosulfonate, the result shows: the bark sodium lignosulfonate is better than the wood calcium lignosulfonate in surfactivity, dispersity and clean solution's fluidity. Molecular weight distribution is relatively narrow and the molecular weight is relatively small; According to the total function groups' content of hydrophilic group, the content of sodium lignosulfonate is obviously higher. Thereof, the bark sodium lignosulfonate has wider application prospects than the wood calcium lignosulfonate. Because of the phenolic compounds, the content of methoxy is lower than the wood calcium lignosulfonate. Studies have also shown: Formaldehyde was used to improve the yield. But it is not obvious to clean solution's fluidity and the other physical and chemical properties of the lignosulfonate. 5,Clean solution's fluidity of lignosulfonate of the bark obviously higher is due to the existence of tannin and phenolic acid; And the higher surface tension and dispersity are the result of tannin and phlobaphen.