Polyaspartic acid(PASP)is suitable for the inhibition of scale deposition from water.To enhance its in- hibition efficiency,PASP was modified by reacting aspartic acid(Asp)with glutamic acid(Glu)to provide Asp-Glu cop...Polyaspartic acid(PASP)is suitable for the inhibition of scale deposition from water.To enhance its in- hibition efficiency,PASP was modified by reacting aspartic acid(Asp)with glutamic acid(Glu)to provide Asp-Glu copolymer under microwave irradiation.The influence of reaction parameters on conversion,molecular weight and inhibition of CaCO3 precipitation was investigated Infra-red.(IR), 1H nuclear magnetic resonance( 1H NMR)and 13C nuclear magnetic resonance( 13C NMR)spectroscopies were used to characterize the copolymer.The results show that copolymerization of aspartic acid and glutamic acid is catalyzed by a small amount of phosphorous acid (H3PO4)in solvent,the product conversion is 98.05%under the following conditions:the molar ratio of glutamic acid to reactant[Glu/(Asp+Glu)]is 0.3 and that of catalyst(Cat)to reactant[Cat/(Glu+Asp)]is 0.05(0.65ml H3PO4),the volume of solvent dimethylformamide is 16ml,the microwave power used is 720W and the reaction for 3 min.The weight average molecular weight of copolymer synthesized under these conditions is 2709 and the inhi- bition rate for CaCO3 is 97.75%.展开更多
A rapid method of microwave assisted acid hydrolysis was established to prepare κ-carra-oligosaccharides. The optimal hydrolysis condition was determined by an orthogonal test. The degree of polymerization （DP） of ...A rapid method of microwave assisted acid hydrolysis was established to prepare κ-carra-oligosaccharides. The optimal hydrolysis condition was determined by an orthogonal test. The degree of polymerization （DP） of oligosaccharides was detected by high performance thin layer chromatography （HPTLC） and polyacrylamide gel electrophoresis （PAGE）. Considering the results of HPTLC and PAGE, the optimum condition of microwave assisted acid hydrolysis was determined. The concentration of κ-carrageenan was 5 mgmL-1; the reaction solution was adjusted to pH 3 with diluted hydrochloric acid; the solution was hydrolyzed under microwave irradiation at 100 ℃ for 15 min. Oligosaccharides were separated by a Superdex 30 column （2.6 cm × 90 em） using AKTA Purifier UPC100 and detected with an online refractive index detector. Each fraction was characterized by electrospray ioni- zation mass spectrometry （ESI-MS）. The data showed that odd-numbered κ-carra-oligosaccharides with DP ranging from 3 to 21 could be obtained with this method, and the structures of the oligosaccharides were consistent with those obtained by traditional mild acid hydrolysis. The new method was more convenient, efficient and environment-friendly than traditional mild acid hydrolysis. Our results provided a useful reference for the preparation of oligosaceharides from other polysaccharides.展开更多
This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied....This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied. Using the proposed method, we analyzed the glucose standard solution, the coefficient of variation being less than 2%. Compared with the traditional electric stove heating method, the results of F-test and T-test showed that there was no significant difference between the two methods, but the microwave method had slightly higher precision and reproducibility than the electric stove method. With the microwave heating method, several seawater samples from Jiaozhou Bay and the South Yellow Sea were also analyzed. The recovery was between 97.5% and 104.3%. This new method has the advantages of shortening the heating time, improving the working efficiency and having simple operation and therefore can be used to analyze the COD in seawater.展开更多
基金Supported by Harbin Key Technologies R&D Program(No.2003AA4CS123).
文摘Polyaspartic acid(PASP)is suitable for the inhibition of scale deposition from water.To enhance its in- hibition efficiency,PASP was modified by reacting aspartic acid(Asp)with glutamic acid(Glu)to provide Asp-Glu copolymer under microwave irradiation.The influence of reaction parameters on conversion,molecular weight and inhibition of CaCO3 precipitation was investigated Infra-red.(IR), 1H nuclear magnetic resonance( 1H NMR)and 13C nuclear magnetic resonance( 13C NMR)spectroscopies were used to characterize the copolymer.The results show that copolymerization of aspartic acid and glutamic acid is catalyzed by a small amount of phosphorous acid (H3PO4)in solvent,the product conversion is 98.05%under the following conditions:the molar ratio of glutamic acid to reactant[Glu/(Asp+Glu)]is 0.3 and that of catalyst(Cat)to reactant[Cat/(Glu+Asp)]is 0.05(0.65ml H3PO4),the volume of solvent dimethylformamide is 16ml,the microwave power used is 720W and the reaction for 3 min.The weight average molecular weight of copolymer synthesized under these conditions is 2709 and the inhi- bition rate for CaCO3 is 97.75%.
基金supported by the Special Fund for Marine Scientific Research in the Public Interest (201005024)NSFC-Shandong Joint Fund for Marine Science Research Centers (U1406402)+1 种基金Qingdao Science & Technology Project (11-2-2-1-hy)National Science & Technology Support Program of China (2013BAB 01B02)
文摘A rapid method of microwave assisted acid hydrolysis was established to prepare κ-carra-oligosaccharides. The optimal hydrolysis condition was determined by an orthogonal test. The degree of polymerization （DP） of oligosaccharides was detected by high performance thin layer chromatography （HPTLC） and polyacrylamide gel electrophoresis （PAGE）. Considering the results of HPTLC and PAGE, the optimum condition of microwave assisted acid hydrolysis was determined. The concentration of κ-carrageenan was 5 mgmL-1; the reaction solution was adjusted to pH 3 with diluted hydrochloric acid; the solution was hydrolyzed under microwave irradiation at 100 ℃ for 15 min. Oligosaccharides were separated by a Superdex 30 column （2.6 cm × 90 em） using AKTA Purifier UPC100 and detected with an online refractive index detector. Each fraction was characterized by electrospray ioni- zation mass spectrometry （ESI-MS）. The data showed that odd-numbered κ-carra-oligosaccharides with DP ranging from 3 to 21 could be obtained with this method, and the structures of the oligosaccharides were consistent with those obtained by traditional mild acid hydrolysis. The new method was more convenient, efficient and environment-friendly than traditional mild acid hydrolysis. Our results provided a useful reference for the preparation of oligosaceharides from other polysaccharides.
文摘This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied. Using the proposed method, we analyzed the glucose standard solution, the coefficient of variation being less than 2%. Compared with the traditional electric stove heating method, the results of F-test and T-test showed that there was no significant difference between the two methods, but the microwave method had slightly higher precision and reproducibility than the electric stove method. With the microwave heating method, several seawater samples from Jiaozhou Bay and the South Yellow Sea were also analyzed. The recovery was between 97.5% and 104.3%. This new method has the advantages of shortening the heating time, improving the working efficiency and having simple operation and therefore can be used to analyze the COD in seawater.
