Identification and decarboxylase activities of bacteria isolated from decomposed mahimahi (Coryphaena hippurus) after incubation at 0 and 32°C

Identification and amine-forming ability of bacterial isolates from decomposed mahimahi (Coryphaena hippurus) were studied in order to identify spoilage microflora and determine the potential for a chemical index of spoilage based on the metabolites produced. Mesophilic bacteria isolated from a fish incubated at 32°C for 24 h were essentially all Gram-negative rods; 89% of these were Vibrio alginolyticus. Strong histamine-forming (> 100 mg/100 ml) mesophiles consisted of eight cultures of Morganella morganii and one of Proteus mirabilis. Weak histamine-forming (< 10 mg/100 ml) mesophiles were all V. alginolyticus, and these comprised 15% of the isolates assigned to that species. Decarboxylation of ornithine and lysine occurred in 38 and 92%, respectively, of the mesophilic isolates. Psychrotrophic isolates obtained from a fish incubated 14 days at 0°C were predominantly Gram-negative genera. Of these, 9% were histamine-forming cultures of Alteromonas putrefaciens, a weak histamine former that produced < 1 mg/100 ml at 5 and 20°C. Decarboxylation of ornithine and lysine occurred in 13 and 15%, respectively, of the psychrotrophic isolates.     

Pilot plant study of post-combustion carbon dioxide capture by reactive absorption: Methodology, comparison of different structured packings, and comprehensive results for monoethanolamine

Post-combustion carbon capture (PCC) from fossil fuel power plants by reactive absorption can substantially contribute to reduce emissions of the greenhouse gas CO₂. To test new solvents for this purpose small pilot plants are used. The present paper describes results of comprehensive studies of the standard PCC solvent MEA (0.3 g/g monoethanolamine in water) in a pilot plant in which the closed cycle of absorption/desorption process is continuously operated (column diameters: 0.125 m, absorber/desorber packing height: 4.25/2.55 m, packing type: Sulzer BX 500, flue gas flow: 30-110 kg/h, CO₂ partial pressure: 35-135 mbar). The data establish a base line for comparisons with new solvents tested in the pilot plant and can be used for a validation of models of the PCC process with MEA. The ratio of the solvent to the flue gas mass flow is systematically varied at constant CO₂ removal rate, and CO₂ partial pressure in the flue gas. Optimal operating points are determined. In the present study the structured packing Sulzer BX 500 is used. The experiments with the removal rate variation are carried out so that the results can directly be compared to those from a previous study in the same plant that was carried out using Sulzer Mellapak 250.Y. A strategy for identifying the influence of absorption kinetics on the results is proposed, which is based on a variation of the gas load at a constant L/G ratio and provides valuable insight on the transferability of pilot plant results.     

Dynamic modeling of CO2 absorption from coal-fired power plants into an aqueous monoethanolamine solution

Among carbon capture and storage (CCS), the post-combustion capture of carbon dioxide (CO₂) by means of chemical absorption is actually the most developed process. Steady state process simulation turned out as a powerful tool for the design of such CO₂ scrubbers. Besides steady state modeling, transient process simulations deliver valuable information on the dynamic behavior of the system. Dynamic interactions of the power plant with the CO₂ separation plant can be described by such models. Within this work a dynamic process simulation model of the absorption unit of a CO₂ separation plant was developed. For describing the chemical absorption of CO₂ into an aqueous monoethanolamine solution a rate based approach was used. All models were developed within the Aspen Custom Modeler^® simulation environment. Thermo physical properties as well as transport properties were taken from the electrolyte non-random-two-liquid model provided by the Aspen Properties^® database. Within this work two simulation cases are presented. In a first simulation the inlet temperature of the flue gas and the lean solvent into the absorber column was changed. The results were validated by using experimental data from the CO₂SEPPL test rig located at the Dürnrohr power station. In a second simulation the flue gas flow to the separation plant was increased. Due to the unavailability of experimental data a validation of the results from the second simulation could not be achieved.     

Synthesis and Properties of Dodecyldiethoxylamine Oxide

Dodecyldiethoxylamine oxide (DDEAO) was synthesized by the reaction of dodecyldiethoxylamine with hydrogen peroxide in water as the solvent. Surface activity, wetting ability and emulsifying capacity were investigated and compared with that of dodecyldimethylamine oxide (DDMAO). Results indicate that the critical micelle concentration (CMC) of DDEAO is lower than that of DDMAO, while its surface tension at CMC (γ_CMC) is slightly higher. The wetting ability of DDEAO is similar to that of DDMAO. For its capacity of emulsifying liquid paraffin, DDEAO is found to be better than DDMAO, but it is the opposite for emulsifying soybean oil. The foaming properties and thickening function of DDEAO in mixtures with alcohol ether sulfate and alkylbenzene sulfonate were also studied. As expected, complex surfactant systems exhibit good foaming ability and DDEAO exhibits a good thickening function.     

Encapsulation of aliphatic amines into nanoparticles for self-healing corrosion protection of steel sheets

A noble approach based on the encapsulation of corrosion inhibitors has been presented, which are capable of improving the active corrosion protection without negatively influencing the barrier properties of the coating layers. Polymeric nanocapsules loaded with six types of amine corrosion inhibitors were synthesized by multi-stage emulsion polymerization. Depending on the basicity and water solubility of amines, different amounts of releasable corrosion inhibitors were encapsulated into the polymer capsules. Encapsulated organic amines were generally well released under alkaline conditions, and linear amines were more easily released from inside capsules than branched ones. The nanocapsules were incorporated into the coating resin and were coated on cold-rolled steel sheets to investigate corrosion protection efficiencies. The corrosion inhibitive efficiencies of the nanocapsule-containing coating layers were evaluated by electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). In this study, it was revealed that the intrinsic properties of the amines as well as their encapsulation/release behaviors determined the barrier property and self-healing protection capability of the coating layer.     

Theoretical Investigation of Some High‐Performance Novel Amine Azide Propellants

Monomethylhydrazine (MMH) is currently the most widely used hypergolic propellant, due to its high performance and low ignition delay. However, its toxicity is a major concern. The present work aims at developing high‐performance hypergolic fuels that are based on tertiary amine azide functionality. A number of potential amine azide candidates have been proposed, and some of their physical and chemical properties have been computed using state‐of‐the‐art molecular modeling techniques. Gas‐phase heats of formation have been calculated using the CBS‐QB3 method, and the first‐principle COSMO‐RS method has been used to compute heats of vaporization and vapor pressures. A density correlation, based on molecular‐volume calculation, has been established to predict the densities of the candidate molecules. Finally, the liquid‐phase heats of formation and densities have been used to predict the specific and density impulses of the proposed candidate molecules. The results show that many of the molecules proposed here have much higher density impulse than that of MMH, and may be considered for experimental studies.     

四种胺类捕收剂体系中两相泡沫和赤铁矿/石英三相泡沫的稳定性

选取赤铁矿和石英两种纯矿物,十二胺、十二烷基三甲基氯化铵、GE609、N-十二烷基乙二胺四种胺类捕收剂,研究了不同pH值和捕收剂浓度对两相泡沫稳定性的影响以及不同粒级的赤铁矿和石英对三相泡沫稳定性的影响。结果表明,除N-十二烷基乙二胺外,其余三种胺类捕收剂溶液的泡沫半衰期均随着捕收剂浓度的增加呈现先升高后降低的趋势,且泡沫稳定性总体呈现酸性>中性>碱性的规律。N-十二烷基乙二胺的泡沫半衰期随浓度的增加逐渐升高,泡沫稳定性呈现碱性>中性>酸性的规律;在四种胺类捕收剂体系中,加入不同粒级石英或者赤铁矿颗粒后均能够在一定程度上提高泡沫的稳定性,颗粒粒度越细,泡沫越稳定,-18μm粒级石英颗粒的影响尤为明显;石英提高泡沫稳定性的程度远高于赤铁矿,加入细粒级的石英颗粒能够大幅度提高泡沫稳定性。微细粒级石英是急剧提高胺类捕收剂浮选泡沫稳定性的关键因素。     

胺类改性剂对尼龙6热氧稳定性能的影响

在己内酰胺水解聚合时加入一定量的受阻胺类改性剂,合成出含有改性剂的改性尼龙6树脂,研究了胺类改性剂对尼龙6的熔体稳定性、相对粘度、端氨基含量及机械性能在热氧作用下的改善效果。实验表明：随着胺类改性剂的加入,尼龙6熔体表观粘度随剪切速率的升高而下降的趋势变缓,熔体加工稳定性提高;与空白试样相比,改性尼龙6的端氨基含量都有不同程度的提高,高温作用下纤维的断裂强度及伸长率的变化幅度明显减小,热氧稳定性得到改善。添加0．1份改性剂后,尼龙6在热加工过程中相对粘度及端氨基含量的变化程度减小;树脂的初始热分解温度、最大热分解温度分别提高3．62℃和5．68℃。     

超细膨润土/环氧树脂复合材料的结构与热性能

采用TG-DTA、IR、SEM、马丁耐热和Daniel流动点测定等方法,研究了有机胺改性超细膨润土与环氧树脂的固化体系的结构及其性能。结果表明,有机胺改性膨润土与环氧树脂固化复合后,可形成由层问固化与层外固化相结合的结构,所得复合材料的耐热性能、分散性均有提高,其中活化有机膨润土／环氧树脂复合体系的分散效果和马丁耐热特性改善更加显著。     

Efficient Removal of Anionic Organic Dyes from Aqueous Solution with Cu‐Organic Frameworks

Cu‐metal‐organic frameworks (Cu‐MOFs) were synthesized in one step using copper acetate, glutamic acid, and small‐molecular organic amines at room temperature. Organic amines served as modulators to modify the structure of Cu‐MOFs. Characterization results proved that the addition of modulators changes the surface morphology. Batch adsorption data indicated high adsorption capacities for anionic organic dyes with glutamic‐Cu‐triethylamine (Glu‐Cu‐TA), higher than that of most MOFs reported. An acid pH was the optimum adsorption parameter. The easy regeneration of recycled Cu‐MOFs suggested there were weak intermolecular interactions between Cu‐MOFs and dyes. The main adsorption forces included electrostatic interaction, ion exchange, π‐π complexation, and hydrogen bonds.