Linoleic acid oxidation catalyzed by various amino acids and cupric ions in aqueous media

Model systems were designed to study linoleic acid oxidation in the presence and absence of various amino acids with or without cupric ions. The tested amino acids exhibited a potential prooxidant effect in linoleic acid dispersed in aqueous media. The effectiveness of various amino acids on linoleic acid oxidation decreased in the following order: cysteine > serine > tryptophan > phenylalanine > histidine > alanine. The addition of alanine, serine, phenylalanine, histidine, or tryptophan to linoleic acid showed an autocatalytic chain reaction. With cysteine, there was a linear relation between concentration of hydroperoxides and time during the early stages of oxidation. The prooxidative activity of the tested amino acids in general could be attributed to the presence of the a-amino group in the form H₃-N-R. The apparent difference in the prooxidative activity is mainly due to the functional groups attached in the β-carbon atom in the amino acid molecules. The addition of cupric ions at a concentration of 10^-5M to linoleic acid catalyzed with various a-amino acids showed that these amino acids had no significant effect. Increasing the copper concentration from 10^-5M to 10^-3M had the following effects: a shortening of the induction period of linoleic acid catalyzed by amino acids having an aromatic side chain, no effect on the induction period but an increase in the oxidation rate during the propagation step in the model systems catalyzed by alanine and serine, and in the model system containing cysteine a linear increase in the linoleic acid oxidation from the start of the reaction.     

Graft copolymerization of acrylic acid to nylon 6 by mutual irradiation. II. The influence of cupric ions

In the γ-irradiation in vacuo of nylon 6 film in the presence of aqueous acrylic acid and different concentrations of cupric chloride, the following relationships have been obtained: R_H ∝ [CuCl₂]^?1.0 and R_G ∝ [CuCl₂]^?0.3 Here [CuCl₂] is the concentration of cupric chloride in the bulk solution, and R_H and R_G denote the initial rates of homopolymerization and grafting, respectively. The values of ?1.0 and ?0.3 for the exponents indicate that the cupric ion is a less effective chain terminator in the film on account of its lower concentration there. Analyses of films grafted in different media demonstrate the copper content of a film to be independent of both the concentration of monomer in the solution and the degree of swelling. The copper content is primarily a function of the total poly(acrylic acid) present, i.e., (grafted species plus occluded homopolymer). Thus, at high doses, where the total poly(acrylic acid) associated with a film is significant, the grafting curves exhibit a falling off, and complex formation between cupric ion and a growing chain is considered a likely contributory factor.     

Linoleic acid oxidation catalyzed by various amino acids and cupric ions in freeze-dried model systems

The present investigation into the effect of amino acids on linoleic acid oxidation in freeze-dried model system illustrates the existence of an autocatalytic chain reaction, in which all amino acids, except cysteine, exhibited minor antioxidant behavior. The antioxidant effect might be attributed to the absence of protonated amino nitrogen. Linoleic acid alone had an induction period of 15 hr, and on the addition of various α-amino acids, the systems had induction periods ranging from 16-19 hr. This increase did not exhibit any specific function for the studied amino acids. Cysteine exhibited an exceptional prooxidant effect due to the role of the HS-group. The addition of copper at concentrations of 10^-5M and 10^-3M to the model systems composed of linoleic acid and various a-amino acids exhibited minor and highly prooxidant effects, respectively, The prooxidant effect of these amino acids in the presence of copper might be due to amino acids-copper complexes.     

Experimental studies on extraction of cobalt ions from dilute aqueous solutions by using complexation-ultrafiltration process

The extraction of cobalt ions from dilute aqueous solutions was investigated by ultrafiltration with the help of poly(acrylic acid) sodium salt (PAASS). Polysulfone and polyethersulfone hollow fiber ultrafiltration membranes were employed in this process. The kinetics of complexation reaction was studied for PAASS with Co²⁺. Results showed that, under a large excess of PAASS, it takes 65, 55 and 40 min at pH 5, 6 and 7, respectively, to get the equilibrium of complexation. The reaction kinetics can be described by a pseudo-first-order equation. Then, the effects of various parameters on the extraction of Co²⁺ were examined in detail. Results indicated that loading ratio, pH value and low-molecular competitive complexing agent affect significantly cobalt rejection coefficient R. Furthermore, a concentration experiment was carried out at pH 7. With increasing volume concentration factor, membrane flux declines slowly, and R value is always about 1. The concentrated retentate was used further for a decomplexation experiment. The decomplexation ratio of cobalt-PAASS complex reaches as high as 90.1%. After the decomplexation step, a diafiltration experiment was performed at pH 2.5. Cobalt ions can be extracted satisfactorily from the retentate, and a purified PAASS is obtained.     

Clarification of succinic acid fermentation broth by ultrafiltration in succinic acid bio–refinery

BACKGROUND: Succinic acid is an important precursor chemical for the synthesis of high value‐added products. In this work, ultrafiltration was first investigated to clarify succinic acid fermentation broth by integrating fermentation and separation and removal processes of the product in situ. Four different ultrafiltration membranes (PES 100 kDa, PES 30 kDa, PES 10 kDa and RC 10 kDa) were used in this work. RESULTS: Results indicate that ultrafiltration is feasible for clarifying succinic acid fermentation broth. Almost all the microorganism cells (99.6%) were removed from the fermentation broth. Proteins were also removed effectively by all the membranes studied. The removal rate was 79.86% for PES 100 kDa, 86.43% for PES 30 kDa, 86.83% for PES 10 kDa, and 80.06% for the RC 10 kDa. After ultrafiltration, a clearer permeate was obtained compared with that from centrifugation. CONCLUSION: Membranes operating at high flux are always susceptible to rapid fouling. Compared with molecular weight cut‐offs (MWCO), membrane material has a significant influence on the flux. Membrane flux measured in this study shows industrial potential of this technology in treatment of succinic acid fermentation broth. © 2012 Society of Chemical Industry     

Experimental studies on extraction of cobalt ions from dilute aqueous solutions by using complexation-ultrafiltration process

The extraction of cobalt ions from dilute aqueous solutions was investigated by ultrafiltration with the help of poly(acrylic acid) sodium salt (PAASS). Polysulfone and polyethersulfone hollow fiber ultrafiltration membranes were employed in this process. The kinetics of complexation reaction was studied for PAASS with Co²⁺. Results showed that, under a large excess of PAASS, it takes 65, 55 and 40 min at pH 5, 6 and 7, respectively, to get the equilibrium of complexation. The reaction kinetics can be described by a pseudo-first-order equation. Then, the effects of various parameters on the extraction of Co²⁺ were examined in detail. Results indicated that loading ratio, pH value and low-molecular competitive complexing agent affect significantly cobalt rejection coefficient R. Furthermore, a concentration experiment was carried out at pH 7. With increasing volume concentration factor, membrane flux declines slowly, and R value is always about 1. The concentrated retentate was used further for a decomplexation experiment. The decomplexation ratio of cobalt-PAASS complex reaches as high as 90.1%. After the decomplexation step, a diafiltration experiment was performed at pH 2.5. Cobalt ions can be extracted satisfactorily from the retentate, and a purified PAASS is obtained.     

Effect of cupric ions on serum and liver cholesterol metabolism

Cupric ions were administered subcutaneously to male Sprague-Dawley rats at a single dose of 200 μmol/kg. At 24 hr after administration, a remarkable increase of total and free cholesterol was seen in the rat serum. Also, when lecithin-cholesterol acyltransferase (LCAT) (E.C. 2.3.1.43) activity was expressed as the percentage of the total serum that free cholesterol esterified, the acyltransferase activity in rats treated with cupric ions showed a slight decrease while the triglyceride content in rat serum and liver decreased by 54% and 61%, respectively. However, the content of hepatic cholesterol in rats treated with cupric ions did not show such a marked change. On the other hand, acid cholesteryl ester hydrolase activity (Acid CEH) (E.C. 3.1.1.14) in liver lysosomes of rats treated with cupric ions showed a marked decrease with increasing cupric ion concentration both in vivo and in vitro. Furthermore, cupric ions caused a marked release of the lysosomal enzymes cathepsin D and β-glucuronidase into the cytosolic fraction. The changes in acid cholesteryl ester hydrolase activity induced by cupric ions appear to be a direct effect of cupric ions on the enzyme. These results suggest that excessive cupric ion concentrations could cause various disorders in lipid metabolism.     

Simultaneous reduction of perrhenate and nickel ions by hypophosphite

Conclusion Reduction of water by hypophosphite during Ni-P-Re alloy deposition proceeds in nearly the same proportion as that in the case of Ni-P deposition according to the mass spectrometric analysis of the gas evolved in deuterium-labelled electroless plating solutions. Perrhenate ion is reduced to metal rhenium as shown by the XPS analysis of the electrolessly deposited Ni-P-Re coating. Atomic hydrogen is expected to tkae part in perrhenate reduction at the catalyst surface resulting in a high hypophosphite efficiency in the overall electroless Ni-P-Re deposition process.     

壳聚糖对化学镀镍废液中Ni2+的吸附

研究了用壳聚糖吸附化学镀镍废液中Ni2 的最佳条件及其脱附和再生方法,以及镀液中络合剂等其他组分对吸附率的影响.结果表明,壳聚糖对化学镀镍废液中的Ni2 具有较好的吸附能力,pH是影响吸附的主要因素.在室温、pH=5.0时,Ni2 质量浓度为4.695 2 g/L的化学镀镍废液被0.939 0 g壳聚糖吸附2 h后,Ni2 的去除率达72.25%.     

壳聚糖对化学镀镍废液中Ni^2＋吸附

研究了用壳聚糖吸附化学镀镍废液中Ni^2＋的最佳条件及其脱附和再生方法，以及镀液中络合剂等其他组分对吸附率的影响。结果表明，壳聚糖对化学镀镍废液中的Ni^2＋具有较好的吸附能力，pH是影响吸附的主要因素。在室温、pH=5．0时，Ni^2＋质量浓度为4．6952g／L的化学镀镍废液被0．9390g壳聚糖吸附2h后，Ni^2＋的去除率达72．25％。     

高效液相色谱法测定丁二酸、戊二酸和己二酸

建立了混合二元酸的反相离子对液相色谱法 ,使极性强、电离常数非常接近的丁二酸、戊二酸和己二酸得到完全分离。该方法与气相色谱法相比 ,样品不需预处理 ,分析速度快。绘制了标准工作曲线     

Lewis酸性离子液体催化合成丁二酸二异丙酯

采用两步法制备了9种不同的Lewis酸性离子液体,采用¹H NMR、FT-IR对离子液体的结构进行了表征,并系统地考察了其对丁二酸和异丙醇酯化反应的催化性能。结果表明,离子液体随着卤化物用量增加表现出更强的酸性。其中[Bmim]Br-Fe₂Cl₆催化合成丁二酸二异丙酯效果良好,催化剂用量为丁二酸质量的10.0%,反应温度100℃,反应时间4 h,酸醇摩尔比为1：5,丁二酸二异丙酯收率为88.9%,酯化率达92.7%。离子液体重复使用6次后,产品收率下降1.7%。     

Metal inactivation in edible oils by carboxymethylmercapto succinic acid

Summary Carboxymethylmercapto succinic acid was one of the most effective metal inactivators examined for use in glyceride oils. The effectiveness is based on oxidative A.O.M. peroxide tests and on the organoleptic evaluation of various types of oils and shortenings. Indexes as high as 80-fold have been observed in preventing peroxide development. Extensive taste panel evaluations have shown significant improvements in the initial flavor and flavor stability of oils and shortenings treated with this mercapto acid. Indications are that the material has an extremely low order of toxicity. Acute tests have shown that the toxicity of the sodium salt is less than that of sodium citrate. The thermal instability to withstand deodorization temperatures and the possibility of the development of a mercaptan odor and taste in oils subjected to a high temperature is a serious disadvantage. Under some conditions the low order of fat solubility and the poisoning of hydrogenation catalyst would be detrimental in some oil-processing operations. Carboxymethylmercapto succinic acid and its derivatives may find use in salad oils, special hydrogenated oils for candy, icing, etc., vitamin preparations, drugs, and similar products where excellent trace metal-inactivating properties are required and where exposure to high temperatures is not encountered. Presented at the spring meeting of the American Oil Chemists’ Society, May 4–6, 1953, in New Orleans, La. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Service, U. S. Department of Agriculture.     

Anaerobiospirillum succiniciproducens厌氧发酵产琥珀酸的培养基优化研究

采用Plackett-Burman设计法,对影响Anaerobiospirillum succiniciproducens产琥珀酸的11个因素进行了筛选.结果表明,影响该菌厌氧发酵产琥珀酸的培养基的主要成分为葡萄糖、酵母抽提物和MgCO3.在此基础上,采用响应面法对其中3个显著因子的最佳水平范围进行研究.通过对二次多项回归方程求解得知,葡萄糖、酵母抽提物和MgCO3的质量浓度分别为39.17、14.68g/L和25.76g/L时,琥珀酸的产量从10.87g/L提高到22.31g/L.     

Investigation on the effect of oxalic acid,succinic acid and aspartic acid on the gas hydrate formation kinetics

Gas hydrate reserves are potential source of clean energy having low molecular weight hydrocarbons trapped in water cages. In this work, we report how organic compounds of different chain lengths and hydrophilicities when used in small concentration may modify hydrate growth and either act as hydrate inhibitors or promoters. Hydrate promoters foster the hydrate growth kinetics and are used in novel applications such as methane storage as solidified natural gas, desalination of sea water and gas separation. On the other hand, gas hydrate inhibitors are used in oil and gas pipelines to alter the rate at which gas hydrate nucleates and grows. Inhibitors such as methanol and ethanol which form strong hydrogen bond with water have been traditionally used as hydrate inhibitors. However, due to relatively high volatility a significant portion of these inhibitors ends up in gas stream and brings further complexity to the safe transportation of natural gas. In this study, organic additives such as oxalic acid, succinic acid and L-aspartic acid (all three) having—COOH group(s) with aspartic acid having an additional—NH₂ group, are investigated for gas hydrate promotion/inhibition behavior. These compounds are polar in nature and thus have significant solubility in liquid water; the presence of weak acidic and water loving (carboxylic/amine groups) moieties makes these organic acids an excellent candidate for further study. This study would pave ways to identify a novel(read better) promoter/inhibitor for gas hydrate formation. Suitable thermodynamic conditions were generated in a stirred tank reactor coupled with cooling system; comparison of gas hydrate formation kinetics with and without additives were carried out to identify the effect of these acids on the formation and growth of hydrates. The possible mechanisms by which these additives inhibit or promote the hydrate growth are also discussed.     

Cation exchange of surface protons on silica gel with cupric ions

The exchange of surface protons on silica gel with cupric ions was investigated under two different conditions. The equilibrium constant was determined and the mechanism of the exchange was suggested. In ammonia water, two protons exchange with one tetrammine cupric ion and formed two ammonium ions. In acidic solution, where one proton exchanges with one cupric ion, the apparent equilibrium constant increases with an increase in the amount of copper loading. The structure of surface species on silica gel was suggested from the mechanism of the exchange and from ESR study. The surface species prepared in acidic solution is changed into the one prepared in ammonia water by exposure to ammonia. The change in the structure of surface species by the adsorption of foreign molecules was also studied.     

产琥珀酸放线杆菌固定CO_2制备丁二酸

在富含CO2的厌氧环境下,产琥珀酸放线杆菌NJ113固定CO2合成丁二酸作为主要代谢终产物。在5 L发酵罐探讨了培养条件对产琥珀酸放线杆菌NJ113固定CO2制备丁二酸的影响。考察了CO2供体形式、通气量、搅拌转速、培养温度和pH值对产琥珀酸放线杆菌NJ113厌氧发酵过程中CO2固定速率以及丁二酸产率的影响。结果表明,选择CO2气体作为CO2供体,CO2通气量为0.75 L/min,搅拌转速达到200 r/min,培养温度为37℃,NaOH调节pH值为6.6,可增加细胞内可利用的CO2。在此优化条件下培养,CO2固定速率达到0.6 g/(L.h),丁二酸产率达到1.61 g/(L.h)。     

用电去离子过程从稀溶液中回收镍离子并制备纯水

利用基于EDI工艺的单个过程实现了低浓度废水中镍的回收并同时制备纯水.研究表明:当原水镍含量为55ppm时,镍去除率可达99.9%以上,淡水产水中镍的浓度低于0.05mg·L-1,其电阻率稳定在2.02～2.59MΩ•cm,浓水中镍浓度则可高达1263mg·L-1.该研究充分证明了EDI可用于回收低浓度含镍废水中的镍离子且同时产生优质纯水,从而可实现如电镀等行业的清洁生产和闭路循环。     

利用甘蔗糖蜜半连续发酵生产琥珀酸

为获得较高的琥珀酸发酵产量和生产强度,对Actinobacillus succinogenes CGMCC1593两级双流半连续发酵甘蔗糖蜜生产琥珀酸的工艺过程进行了研究。通过对一级罐初始总糖浓度、补加培养基体积分数和批次发酵时间等发酵条件的优化,琥珀酸产量较分批发酵36 h提高12.9％,与补料分批发酵结果接近;生产强度较分批发酵和补料分批发酵分别提高111％和114%。