Pd Ni Catalytic Lac Modification Process And Mechanism Study

Three domains correlated with the process and the mechanism involved into seedlac,a natural high molecule polymer,were carried out in this thesis Firstly,the catalytic hydrodechlorination added with Pd and Ni for removal compact chlorine entered into the molecule structure of seedlac while bleached with sodium hypochlorite was investigated.Moreover,the catalytic technology with ultrosound that aleuritic acid extracted from seedlac by saponification was also investigated in this study.Finally,waste water resulted from the modification and sopanification process had been treated with an effective measure originated in this thesis which was nominated as catalytic electrooxidation.Two novel methods of dechlorination process were investigated in the thesis for making it possible to manufacture the shellac with lower chlorine content and to meet the qualification the shellac could be used in food industry and pharmarceutical domains.One was hydrodechlorination catalysed by Pd/Fe,Pd/C,and Pd/C in the presence of hydrogen.And the other was elimination.The experimental results demonstrated that the final products with chlorine content as much as 0.46%,0.44%and 0.3%were obtained when Ni/Fe,Pd/Fe and Pd/C were used as catalyst respectively through the former,and that the chlorine content in the final product was also less than 0.3%when the later was applied.On the other hand,the chlorine content in the final product of defferent process mentioned above was only one fifth to one eighth and one eighth to one tenth respectively in proportioned with that before treated.However,it was higher than one third claimed in literary.Besides,the factors influencing the dechlorination in processes had been studied,as well as the mechanism of dechlorination by dynamics reaction calculation and by the structure characterisation by use of FT-IR, Organatic Elementary Analyser,Ultraviolet visible spectroscopy meter etc. The results drew up in the thesis indicated that the catalytic hydrodechlorination raction was first order reaction,and that so did to the elimination dechlorination raction.Moreover,the apprarent activation engery of elimination dechlorination at the temperatue between 80℃and 90℃was 38.24kJ·mo1^-1which was deducted from the experiment data. Furthermore,through modeled and calculated the relation of chlorine content C of final products with the influence factors such as initial chlorine content C₀,reaction time t,reaction temperature T and quantity of dechlorination reagent Q in the dechlorination process a equation was got: C = 3.0814 - 0.0047t - 0.0223T - 0.4228Q + 0.1336C₀.Inaddition,the process and mechanism of aleuritic acid extracion from seedlac by saponification catalyzed with ultrasound wave were investigated in the thesis.Compared with ultrasonic reaction,other two approaches of saponification were also carried out.One was regular method at room temperature,and the other was enhancing way protected by anhydrous sodium sulfite at a temperature higher than ambient temperature.As a result, the experiments indicated that none organic solvent was used in each process,and fine products can be directly got without any refinery process, and that products with content as much as above 98.0%could be obtained in each process.The experimental results of each process were routed as follows.Firstly,the final products with aleuritic acid content in the range of 98.85%to 99.43%could be got,and the yield of aleuritic acid could reach the scale between 24.64%and 25.16%when seedlac was saponified with 25%NaOH under the conditions of temperature 80℃for 96h.Secondly,the final products with aleuritic acid content in the scale between 98.55%and 99.53%could be achieved,and the yield of product was on the scale between 28.09%and 29.14%when the raw material was reacated with 25%NaOH at room temperature for 7d.Finally,the final products with a scale between 98.5%and 99.63%could be got,and its yield could be reached above 24.0%when the goods was treated with 25%NaOH catalysed by ultrosonic wave with a power 250W at 75℃for 10min.Finally,two motivated methods were also investigated in the thesis for treating the waste water produced in the process seedlac was modified.One was named catalytic electrooxidation,which waste iron scrap was used as catalyst,and hydrogen peroxide was used as oxidation agent.It was demonstrated that the removal efficiency of COD could reach 95.1%to 96.4%and COD decreased to the range between 80 mg/L and 110 mg/L from the original much as 2200mg/L when electrolyzed with stainless steel cathod for 20 h,and that the removal efficiency of COD could reach the scale between 96.9%and 97.8%while COD degraded to the scope of 50 mg/L to 70 mg/L from the original much as 2200mg/L while electrolyzed with graphite cathode for 16h.The other one was Fenton reagent combined with micro-battery,which let COD decrease to the range between 200mg/L and 300 mg/L from 2200mg/L with COD removal efficiency 90.7%.