The transesterification reaction conditions of tung oil with methanol have been studied in this article, with immobilized lipase NOVO435 as catalyst. The response surface methodology was used to optimize the transeste...The transesterification reaction conditions of tung oil with methanol have been studied in this article, with immobilized lipase NOVO435 as catalyst. The response surface methodology was used to optimize the transesterification reaction of tung oil in a nonsolvent system. The optimal conditions were rotation rate 200 r/min, molar ratio of methanol to oil 2.2： l, reaction temperature 43℃, and the catalyst amount 14% （based on the weight of oil）. After reacting for 18 h, 67.5% of the oil was converted to its corresponding methyl esters （the theoretical ester conversion was 73.3%）. The lipase was washed by organic solvents after each reaction and was reused again. The esters conversion of tung oil was decreased by 6% after the lipase was reused for 120 h. The theoretical amount of methanol was added in two steps, 85% ester conversion was obtained after 36 h of reaction （theoretical ester conversion was 100%）. The molar ratio of methanol to oil, the catalyst amount, the reaction temperature, and reaction time were all highly significant factors, and there was a relative significant interaction between every two factors.展开更多
The micro-nano composite structure can endow separation membranes with special surface properties,but it often has the problems of inefficient preparation process and poor structural stability.In this work,a novel ato...The micro-nano composite structure can endow separation membranes with special surface properties,but it often has the problems of inefficient preparation process and poor structural stability.In this work,a novel atomization-assisted nonsolvent induced phase separation method,which is also highly efficient and very simple,has been developed.By using this method,a bicontinuous porous microfiltration membrane with robust micro-nano composite structure was obtained via commercially available polymers of polyacrylonitrile and polyvinylpyrrolidone.The formation mechanism of the micro-nano composite structure was proposed.The microphase separation of polyacrylonitrile and polyvinylpyrrolidone components during the atomization pretreatment process and the hydrogen bonding between polyacrylonitrile and polyvinylpyrrolidone molecules should have resulted in the nano-protrusions on the membrane skeleton.The membrane exhibits superhydrophilicity in air and superoleophobicity underwater.The membrane can separate both surfactant-free and surfactant-stabilized oil-in-water emulsions with high separation efficiency and permeation flux.With excellent antifouling property and robust microstructure,the membrane can easily be recycled for long-term separation.Furthermore,the scale-up verification from laboratory preparation to continuous production has been achieved.The simple,efficient,cost-effective preparation method and excellent membrane properties indicate the great potential of the developed membranes in practical applications.展开更多
采用溶剂-非溶剂的方法,通过加入不同的晶形控制剂制备超细CL-20,并对晶形控制剂的种类和用量、加料方式等因素进行了分析。结果表明,晶形控制剂的种类、用量及样品溶剂加料方式严重地影响着超细CL-20的晶形。对于2.0 g CL-20原料,采用3...采用溶剂-非溶剂的方法,通过加入不同的晶形控制剂制备超细CL-20,并对晶形控制剂的种类和用量、加料方式等因素进行了分析。结果表明,晶形控制剂的种类、用量及样品溶剂加料方式严重地影响着超细CL-20的晶形。对于2.0 g CL-20原料,采用3.5 mL质量浓度2%聚乙烯醇类化合物(PV)晶形控制剂,所得到的超细粉末晶形大多为块状,晶体粒径最小可达到1μm;采用6.5 mL质量浓度5%聚氧乙烯醚类化合物(PT)晶形控制剂,所得到的超细粉末晶形也大多为块状,晶体粒径最小可达到2μm。采用喷壶方式加料,使用6.5 mL质量浓度5%PT晶形控制剂可使晶形呈椭圆形,晶体粒径最小可达到1μm,细化后的CL-20热敏感性更高,晶型仍为ε型。展开更多
文摘The transesterification reaction conditions of tung oil with methanol have been studied in this article, with immobilized lipase NOVO435 as catalyst. The response surface methodology was used to optimize the transesterification reaction of tung oil in a nonsolvent system. The optimal conditions were rotation rate 200 r/min, molar ratio of methanol to oil 2.2： l, reaction temperature 43℃, and the catalyst amount 14% （based on the weight of oil）. After reacting for 18 h, 67.5% of the oil was converted to its corresponding methyl esters （the theoretical ester conversion was 73.3%）. The lipase was washed by organic solvents after each reaction and was reused again. The esters conversion of tung oil was decreased by 6% after the lipase was reused for 120 h. The theoretical amount of methanol was added in two steps, 85% ester conversion was obtained after 36 h of reaction （theoretical ester conversion was 100%）. The molar ratio of methanol to oil, the catalyst amount, the reaction temperature, and reaction time were all highly significant factors, and there was a relative significant interaction between every two factors.
文摘The micro-nano composite structure can endow separation membranes with special surface properties,but it often has the problems of inefficient preparation process and poor structural stability.In this work,a novel atomization-assisted nonsolvent induced phase separation method,which is also highly efficient and very simple,has been developed.By using this method,a bicontinuous porous microfiltration membrane with robust micro-nano composite structure was obtained via commercially available polymers of polyacrylonitrile and polyvinylpyrrolidone.The formation mechanism of the micro-nano composite structure was proposed.The microphase separation of polyacrylonitrile and polyvinylpyrrolidone components during the atomization pretreatment process and the hydrogen bonding between polyacrylonitrile and polyvinylpyrrolidone molecules should have resulted in the nano-protrusions on the membrane skeleton.The membrane exhibits superhydrophilicity in air and superoleophobicity underwater.The membrane can separate both surfactant-free and surfactant-stabilized oil-in-water emulsions with high separation efficiency and permeation flux.With excellent antifouling property and robust microstructure,the membrane can easily be recycled for long-term separation.Furthermore,the scale-up verification from laboratory preparation to continuous production has been achieved.The simple,efficient,cost-effective preparation method and excellent membrane properties indicate the great potential of the developed membranes in practical applications.
基金supported by the Scientific Research Fund of Hunan Provincial Education Department,China(No.15K080)the Fund of Hunan Engineering Laboratory for Preparation Technology of Polyvinyl Alcohol Fiber Material,Huaihua University,China(No.HGY201610)~~
