Efficient Separation Of Crude Tall Oil From Masson Pine Kraft-based Dissolving Pulp Sulfate Soap

In the Masson pine kraft-based dissolving pulp process,it is difficult to efficiently separate crude tall oil?CTO?from the pulping sulfate soap by using the conventional separation techniques.In this paper,we mainly do some composition analysis to the Masson pine kraft-based dissolving pulp sulfate soap.The traditional isolation process for crude tall oil?CTO?was modified to separate the CTO from the pulping sulfate soap efficiently.Furthermore,the optimal parameters via the modified CTO isolation process were determined,including the detergents amount and the agitation rate.We also use the Gas Chromatograph-Mass Spectrometer?GC-MS?technology to do the composition analysis of the crude tall oil sample.Finally,the separation mechanisms for the CTO were studied.Firstly,the main ingredient of the concentrated Masson pine kraft-based dissolving pulp sulfate soap was studied.The results showed that compared with the traditional cooking liquor,the Masson pine kraft-based dissolving pulp waste sulfate soap has a higher residual alkali content and solids content.In addition,the raw material is a more complex system,other than the main components of sulfate soap,it is also mixed with some other ingredients,including the removal lignin of the cooking process,low molecules sugar of hemicellulose depolymerization,residual fibers and the residual inorganic salts of the cooking process et al.Determining the content of these components can be indirectly figure out the theory content of crude tall oil,which provide a data support for the subsequent extraction rate calculation of the crude tall oil.Secondly,combined with the characteristics of Masson pine kraft pulp dissolving pulp waste,the traditional isolation process for crude tall oil?CTO?was modified and improved.The modified CTO separation process includes two-stage process,washing and acidification.The washing process is divided into a first washing and a second washing.The experimental results show that the extraction rate of crude tall oil has a close relationship with the amount of sodium hydroxide,sodium,the stirring speed of the washing process and the amount of acidifying agents.Within a certain range,the extraction rate of crude tall oil is increasing with the increase of the amount of detergent.In the washing process,the rate of stirring device has an great influence on the extraction rate of crude tall oil.The greater the stirring speed,the higher the extraction rate of crude tall oil.Beyond a certain rate,the extraction rate of crude tall oil was stabilized,no longer increases with the increasing rate.A mass fraction of 30%sulfuric acid?H₂SO₄?solution was used as an acidifying agent in the acidification process.When the pH of the reaction system was reached to 3,the acidification process was completed.After an water bath of 100? for 3 h,the CTO products can be isolated from the concentrated Masson pine kratt-based dissolving pulp sulfate soap.Thirdly,using the improved separation process to efficiently separate crude tall oil from the Masson pine kraft-based dissolving pulp sulfate soap and using Gas Chromatograph-Mass Spectrometer?GC-MS?technology to do the composition analysis of the crude tall oil sample.The results showed that the crude tall oil of the Masson pine kraft-based dissolving pulp sulfate soap can be effectively separated with the modified separation process.The extraction rate is up to 94%,achieving the purpose of efficient separation.The GC-MS analysis results showed that the composition separated from the Masson pine kraft-based dissolving pulp sulfate soap is tall oil ingredients.And it contains resin acids,fatty acids and neutral or unsaponifiable materials.Finally,the CTO separation mechanisms were preliminarily studied.By analyzing the impact of the alkali lignin and hemicellulose on the separation of crude tall oil,it is concluded that it is the results of multiple separation mechanisms to stablize the CTO components in the Masson pine kraft-based dissolving pulp sulfate soap.The results show that the lignin molecular weight in dissolving pulp sulfate soap decreased obviously compared to the traditional kraft sulfate soap,and the hydrophilicity of alkali lignin increased a lot.Meanwhile,the resin particles have a relatively high Zeta potential.Hemicellulose polysaccharide small molecules can stablize the compositions of alkali soap in pulp sulfate soap.All these factors result in the low extraction rate of CTO.For the modified separation process,the electric double layer of system of alkali soap can be changed by the sodium sulfate under alkaline conditions,and its stablization may be destroyed.In addition,the additional shear force generated by stirrer and the captures role of the bubbles can lead to an instability of the original colloidal system,and result in the deposition of CTO alkali soap,so as to achieve the purpose of separation.