Degradation Kinetics Of Coconut Chaff In Subcritical Water

Coconut chaff is the coconut shell fiber power,From a medium of natural organic matter degradation, pure natural falling coconut shell fiber processing. Subcritical water (SCW) is under moderate pressure, the water is heated to above 100 ℃ temperatures below the critical temperature 374℃, which remained water in the liquid state. This paper studies the subcritical water Coconut chaff degradation kinetics analysis method calculated degradation rate constant K and the activation energy Ea, subcritical water Coconut chaff degradation products. Provide a theoretical basis for the development of the later devices. Specific work as follows:1. Analysis of the composition of raw materialsCellulose accounted for 28.6% of the total weight of Coconut chaff,Hemicellulose 4.2%, lignin content is the highest, reaching 64.2%, ash content 5.2%.2. Degradation conditions to exploreBy orthogonal and single factor experiment on the degradation temperature (℃) dgradation time (min), ratio of solid to liquid, the particle size (mesh).The reaction temperature, coconut husk degradation process and reaction time, particle size, amount of catalyst on the degradation experiment effect decreases in turn. Degradation optimum conditions:240℃,60min, catalytic amount 120ml, the particle size of 60 mesh. Degradation temperature is the most significant influencing factors,160℃, degradation 60min degradation rate of 22.6%; 240℃, degradation 30min degradation rate of 32.58%.3. Degradation kinetics model and parameters for solvingThe reducing sugar as the primary degradation product, the change in amount of by different degradation under the conditions of a reducing sugar, the establishment of the corresponding kinetic model as follows:Gs=k1/(k2-k1)(exp(-k1t)-exp(-k2t)) Through lstOpt software curve fitting calculated:k1=1.87 (h-1),k2=0.53 (h-1); under conditions of 160℃ under conditions of 180℃, k1=3.95 (h-1), k2=1.32 (h-1); under conditions of 200℃,220℃ under the conditions k1=9.27 (H-1), k2=3.05 (h-1);k1=21.83 (h-1), k2=9.74 (h-1);The 240℃ k1=30.51 (h-1), k2=17.92 (h-1). By Arrhnius equation ki=ki0exp[-Eai/(RT)] derived pre-exponential factor:k10= 3.16×10-8, k20=5.56×10-9; the response activation energy Ea1=68.35KJ/mol,Ea2= 83.27KJ/mol.4. To establish an analytical method of degradation productsA. Qualitative analysis of the productChromatographic conditions:Column:ZORBAX Eclipse XDB-C18(150×4.6 mm 5UL); mobile phase:0.5×10-3mol/L sulfuric acid aqueous solution; flow rate: 1.0mL/min; column temperature:30℃; detection wavelength:284nm; feed the sample volume was:20ul,under conditions of standard glucose-like retention time and suspected glucose average retention time were:1.3353s and 3.3550s, the RDS(%) =0.055.In the chromatographic conditions were:column:ZORBAX Eclipse XDB-C18 (150 x4.6mm 5ul); mobile phase:0.05mol/l; potassium dihydrogen phosphate:acetonitrile (80:20); flow rate:1.OmL/min; column temperature:40℃; detection wavelength:284nm; injection volume:20ul, glucosestandard sample retention time with suspected glucose average retention time:7.491s and 7.478s, the RDS(%)=0.107. Conclusion is suspected of glucose is glucose peakB. The Quantitative AnalysisLinear regression equation experiment:M=204.14C+32.964 R2=1.0000, where M is the peak area, C mass concentrationThe regression equation:5-HMF showed good linear in the concentration range of 0.125ug/mL-10.000ug/mL.Precision test:5 standard stock solution diluted times measured repetitive operation, the average peak area was 290.3, RDS(%) of 0.173, shows higher accuracy. Repeat the experiment:6 copies of the same degradation analysis of 5-HMF content of 0.94ug/ml, RDS =0.173%,The recovery rate experiment:the experiment on the recovery rate, the average recovery rate was 100.06%, the overall recovery rate was 99%-101%, RDS (%)=0.83.