Study On Extraction Of Rosin Residues By Green Solvent Dimethyl Carbonate And Its Kinetics

The oil content of rosin residues was determined by soxhlet extraction using ethanol,ether and petroleum ether as solvents.Study on the method of oil extracted from rosin residues by green solvent dimethyl carbonate and the process was optimized.The on-line tracking analysis for the changes of oil concentration with time were studied and the kinetic models of oil extracted from rosin residues by dimethyl carbonate were established.The main contents are as follows:The components of extracted oil were identified by gas chromatography-mass spectrometry the contents of sesquiterpene and rosin acid were 90.87%.Area correction normalization method was used for quantitative analysis of abietic acid,longifolene and dimethyl carbonate by GC-1102 gas chromatography with DB-5 capillary column(30 m×0.32 mm×O.25 μm).The carrier gas and its flow rate were:nitrogen gas and 48.0 mL·min-1,hydrogen gas flow rate was 32 mL·min-1,split flow ratio was set at 50:1,the flow rate of trail gas was 24 mL·min-1,sensitivity was set at 8,sample volume was 0.3 μL,the temperature of injector and detector were 523.15 K,the temperature program was as follows:328.15K(2min)1K·min-1518.15K1K·min-1 523.15K.The accuracy and recovery of this method were tested and area correction normalization method and area normalization method was compared.The results showed that the maximum relative standard deviation(RSD)of abietic acid,longifolene and dimethyl carbonate was 1.90%,the recoveries of three components were:105.35%,93.09%and 99.09%.The maximum relative deviations of area correction normalization method and area normalization method comparing the actual value were 1.64%and 213.48%.Soxhlet extraction was applied to determine oil content of rosin residues for its character of fully extraction.The effect of solvent,particle size of raw material,ratio of raw material to solvent and extraction time on the determine of oil content of rosin residues were examined by single-factor method.The optimal conditions for the determination of oil content in the rosin residues,ethanol as solvent,were obtained by orthogonal method.The optimal conditions obtained were as follows:raw material particle size 40 mesh,ratio of raw material to solvent 1:14 g·mL-1,extraction time 4.0 h,the oil content of rosin residues could reach 45.33%.The extraction of rosin residues by dimethyl carbonate was investigated in this paper.The effect of particle size of raw material,ratio of raw material to solvent,extraction time,extraction temperature and stirring speed on the yield of oil content were examined by single-factor method.On the base of single-factor experiment,particle size of raw material,ratio of raw material to solvent,extraction time,extraction temperature were chosen as factors,a orthogonal experiment of four factors,four levels was established to optimize the extraction process.The sequence of influential significance was obtained using analysis of extreme difference of orthogonal experiment:particle size of raw material>ratio of raw material to solvent>extraction temperature>extraction time.The optimal extraction conditions were obtained as follows:raw material particle size 40 mesh,ratio of raw material to solvent 1:14 g·mL-1,extraction temperature 55℃,extraction time 120min,the yield of oil could reach 38.57%.The kinetics of the extraction of rosin residues was investigated and a first order model including the stages of washing and diffusion was established on the base of Fick’s law:ln((C∞)/(C∞-C))=ln((C∞)/(C∞-C0))+kdt.The relation between oil concentration and extraction time under different temperatures and raw material particle sizes were tested.The established kinetic model was examined on the base of the experiment data.The experiment data could perfectly match with the first order kinetic model.The rate-determining step for extracting of oil from rosin residues was the diffusion of oil through the residue particles.Base on the Arrhenius equation and experiment data,the active energy and inner diffusion coefficient were obtained:10.83 kJ·mol-1 and 2.471×10-11 m2·s-1.