Reaction kinetic interpretation of heat destruction influenced by environmental factors

Based on reaction kinetics and thermodynamic considerations a mathematical model was developed to describe the thermal death rate of microbes as a function of environmental factors such as temperature, water activity, pH and redox potential. The mathematical model is discussed and validated by fitting to data sets of heat destruction of Lactobacillus brevis and Lactobacillus plantarum. The mathematical analysis of the kinetic model and the parameters of the model fitting demonstrate its applicability both for the prediction of the heat destruction rate and estimation of the thermodynamic parameters of heat destruction.     

Biodegradation of phenolic environmental pollutants by a surfactant-laccase complex in organic media

Oxidative degradation of phenolic environmental pollutants in organic media was investigated using a laccase complexed with surfactants. The catalytic activity of the surfactant-laccase complex in isooctane was markedly enhanced by appropriately adjusting the water content of the reaction medium using reverse micelles. The surfactant-laccase complex showed little activity towards the oxidative reaction of bisphenol A in water-saturated isooctane (i.e., 0.0055% [v/v] water) while effectively catalyzed the same reaction in isooctane containing 4% (v/v) water, which is over the maximum water solubility. The latter system was homogeneous and was only achieved by the aid of reverse micelles. With respect to the oxidation of bisphenol A, two products, 4-isopropylphenol and 4-isopropenylphenol, were identified by gas chromatography-mass spectrometry (GC-MS) analyses, indicating the oxidative degradation of the bis-phenolic structure of bisphenol A. We also found that the surfactant-laccase complex turned out to handle other environmental pollutants, chlorophenols, by the simultaneous addition of water and a redox mediator into the reaction medium using reverse micelles.     

On the reversibility of environmental contamination with persistent organic pollutants

An understanding of the factors that control the time trends of persistent organic pollutants (POPs) in the environment is required to evaluate the effectiveness of emission reductions and to predict future exposure. Using a regional contaminant fate model, CoZMo-POP 2, and a generic bell-shaped emission profile, we simulated time trends of hypothetical chemicals with a range of POP-like partitioning and degradation properties in different compartments of a generic warm temperate environment, with the objective of identifying the processes that may prevent the reversibility of environmental contamination with POPs after the end of primary emissions. Evaporation from soil and water can prevent complete reversibility of POP contamination of the atmosphere after the end of emissions. However, under the selected conditions, only for organic chemicals within a narrow range of volatility, that is, a logarithm of the octanol air equilibrium partition coefficient between 7 and 8, and with atmospheric degradation half-lives in excess of a few month can evaporation from environmental reservoirs sustain atmospheric levels that are within an order of magnitude of those resulting from primary emissions. HCB and α-HCH fulfill these criteria, which may explain, why their atmospheric concentrations have remained relatively high decades after their main primary emissions have been largely eliminated. Soil-to-water transfer is found responsible for the lack of reversibility of POP contamination of the aqueous environment after the end of emissions, whereas reversal of water-sediment exchange, although possible, is unlikely to contribute significantly. Differences in the reversibility of contamination in air and water suggests the possibility of changes in the relative importance of various exposure pathways after the end of primary emissions, namely an increase in the importance of the aquatic food chain relative to the agricultural one, especially if the former has a benthic component. Since simulated time trends were strongly dependent on degradation half-lives, partitioning properties and selected environmental input parameters, it should not be surprising, that different field studies often generate highly divergent time trends.     

Controlling reduction potentials of semiconductor-supported molecular catalysts for environmental remediation of organohalide pollutants

The spectroscopic and redox properties of iron(lll) protoporphyrin chloride (hemin) and cobalt(lll) meso-tetra-(4-carboxyphenyl) porphyrin chloride (CoTCP) were quantified in fluid solution and when anchored to mesoporous nanocrystalline TiO2 thin films. Surface binding was well-described by the Langmuir adsorption isotherm model from which adduct formation constants of 10(5) M(-1) and limiting surface coverages of 10(-8) mol/cm2 were abstracted. In acetonitrile and dimethyl sulfoxide electrolytes, TiO2 binding was found to induce a substantial negative shift in the M(III/II) formal reduction potentials. In DMSO electrolyte, the Co(III/II) and Fe(III/II) potentials were -559 and -727 mV versus ferrocenium/ferrocene (Fc+/Fc) and shifted to -782 and -1063 mV, respectively, after surface binding. The Bronsted acidity of the TiO2 surface was found to correlate with the measured reduction potentials. For TiO2 pretreated with aqueous solutions from pH 4-9, the Co(III/II) potential showed a -66 mV/pH unit change, while the Fe(llI/II) potential of hemin changed by -40 mV/pH from pH 1 to 14. Spectroelectrochemical data gave isosbestic, reversible spectral changes in the visible region assigned to M(III/II) redox chemistry with lambda(iso) = 410, 460, 530, 545, 568, and 593 nm for CoTCP/TiO2 and lambda(iso) = 408, 441, 500, 576, and 643 nm for hemin/TiO2. In aqueous solution, the CoTCP reduction potentials were also found to be pH dependent upon surface binding, with CoTCP = -583 mV and CoTCP/TiO2 = -685 mV versus Fc+/Fc at pH 6. For CoTCP/TiO2, the aqueous pH dependence of the potentials was -52 mV/pH. The rate constant for heme/TiO2 reduction of CCl4 increased from 3.9 +/- 0.7 x 10(-4) to 2.0 +/- 0.1 x 10(-3) s(-1) when the pH was raised from 4 to 8.     

Effect of salts on the binding of some environmental pollutants to corn protein zein studied by HPLC

The strength and the character of the binding of 14 organic solvents to the corn protein zein in distilled water and in various salt solutions were determined by preparing zein-coated carbon stationary phase and by measuring the retention characteristics of solvents on a high-performance liquid chromatographic column filled with this stationary phase. The relationship between the physicochemical parameters and binding characteristics of solvents was elucidated by principal component analysis. It was established that various interactive forces are involved in the binding of solvent to the protein, suggesting a mixed binding mechanism. Binding characteristics are equally influenced by the molecular hydrophobicity and by the polarity parameters of the solvent. Coordination numbers, ionization, and lattice energies of the monovalent cations significantly influenced the various aspects of the binding of organic solvents to zein.     

玉未蛋白发泡粉复合法制备工艺

采用酶法辅助碱法的工艺生产玉米蛋白发泡粉,实验结果表明,当反应温度45℃,反应时间为1h,酶底物比为0.001U.g-1,pH为7.5时,水解液发泡性达到460%,泡沫稳定性为100%。     

Sonochemistry in environmental remediation. 2. Heterogeneous sonophotocatalytic oxidation processes for the treatment of pollutants in water

Recent advances in advanced oxidation technologies for applications in environmental remediation involve the use of acoustic cavitation. Cavitation is the formation, growth, and implosive collapse of gas- or vapor-filled microbubbles formed from acoustical wave-induced compression/ rarefaction in a body of liquid. Cavitation is effective in treating most liquid-phase pollutants but it is highly energy intensive and not economical or practically feasible when used alone. One of the most interesting topics in the recent advances in environmental sonochemistry is the intensification of the ultrasonic degradation process by coupling ultrasound with other types of energy, chemical oxidants, or photocataysts. In Part II of this series, a critical review of the applications of ultrasound in environmental remediation focusing on the simultaneous or hybrid use of ultrasonic irradiation and photocatalysis in aqueous solutions, namely, sonophotocatalytic oxidation processes, is presented.     

湿氧化法预处理蔗渣对酶水解效率的影响

预处理木质纤维素原料有多种方法。对于蔗渣的预处理方法包括：蒸汽爆破法、热水预处理法、过醋酸和氨水预处理法。     

Novel quantitative method for the degree of branching in dextran

A novel quantitative method for the determination of degree of branching in Leuconostoc mesenteroides B-512F dextran was developed by using the combination of 3 dextran-degrading enzymes. First, Paenibacillus sp. endo-dextranase was randomly degraded B-512F dextran into linear or branched isomalto-oligosaccharides with various degree of polymerization (2–8). Second, Streptococcus mutans dextran glucosidase hydrolyzed linear or branched isomalto-oligosaccharides into glucose and branched isomalto-penta-saccharides. Third, the branched isomaltopenta-saccharide was degraded into glucose by using Bacteroides thetaimicron α-glucosidase. The number of branching points in B-512F dextran (5.42%) was determined by the difference in the amount of glucose in the reaction digest between BTGase-PDex and DGase-PDex treatments.     

杂交组合灰色评判方法在甜菜育种中的应用

以10个甜菜杂交组合为试验材料,选择7个与产量和品质有直接关系的性状,以块根中的钾、钠、有害氮的含量及纯度为主要品质性状;以根产量、含糖率和产糖量为主要经济性状,采用杂交组合灰色评判方法,对10个供试材料7个性状进行综合评估。结果表明:组合D2(HQD2×DL2)、D3(HQD2×HQD3)为高产型杂交组合:D7(334-1×DL1)、D9(401×HRC1)为各项性状表现良好的优良组合。采用杂交组合灰色译判方法和常规对比法进行比较,其结果几乎完全一致,说明运用杂交组合灰色评判方法是提高品种选择效率,加快育种进程的有效方法。     

Novel method for producing amorphous rice flours by milling without adding water

The present study investigated a novel milling method for producing amorphous rice starch without adding water. A new type of milling machine was developed (termed the shear and heat milling machine (SHMM)), which is capable of applying mechanical shear and heat during the milling process. The SHMM consisted of a pair of rice mortars attached to a servomotor and a ring heater. The heater was installed on the upper mortar; the temperature of the upper mortar was monitored and controlled by a thermal controller. Wide‐angle X‐ray diffraction (WAXD) analysis was used to determine the crystallinities of starch in rice flour samples produced using the SHMM at different milling temperatures. The WAXD data for milled rice flour that had been heated exhibited no diffraction peaks. This experimental result demonstrates that the developed SHMM produces amorphous rice starch easily by milling with heating without the addition of water. The milling conditions such as the shear and heat applied can be used to control the crystallinity of starch in rice.     

Novel method for determination of myofibril fragmentation post-mortem

Multi angle light scattering was used to determine the myofibril fragmentation of pig longissimus dorsi muscle which was then compared with results from the common turbidity method. The method is based on measurement of the myofibril particle size distribution with the use of a special optical unit containing several individual detectors. The method was able to determine post-mortem changes in a pig muscle homogenate without purification of the myofibrils and is therefore simpler and much faster than the traditional turbidity method. There was a significant correlation (p < 0.01) between Warner–Bratzler shear force (WBSF) and particle size distribution. The root mean square error of prediction was found to be 6.1 N (10–15% of the measured WBSF) when multivariate data analysis was used to make a prediction model for WBSF. Multi angle light scattering is very useful for estimation of myofibril fragmentation since the method is fast and the sample preparation is simple.     

Uptake of organic pollutants by silica--polycation-Immobilized micelles for groundwater remediation

Interest has grown in designing new materials for groundwater treatment via "permeable reactive barriers". In the present case, a model siliceous surface, controlled pore glass (CPG), was treated with a polycation (quaternized polyvinyl pyridine, QPVP) which immobilizes anionic/nonionic mixed micelles, in order to solubilize a variety of hydrophobic pollutants. Polymer adsorption on CPG showed atypically slow kinetics and linear adsorption isotherms, which may be a consequence of the substrate porosity. The highest toluene solubilization efficiency was achieved for the silica-polycation-immobilized micelles (SPIM) with the highest polymer loading and lowest micelle binding, a result discussed in terms of the configuration of the bound polymer and the corresponding state of the bound micelles. The ability of SPIM to treat simultaneously a wide range of pollutants and reduce their concentration in solution by 20-90% was demonstrated. Optimization of SPIM systems for remediation calls for a better understanding of both the local environment of the bound micelles and their intrinsic affinities for different hydrophobic pollutants.     

Sonochemistry in environmental remediation. 1. Combinative and hybrid sonophotochemical oxidation processes for the treatment of pollutants in water

Sonoprocessing is the utilization of sonic and ultrasonic waves in chemical synthesis and processes. It is a new and rapidly growing research field with broad applications in environmental engineering, green chemical synthesis, and processing. The application of this environmentally benign technique in environmental remediation is currently under active research and development. Sonochemical oxidation is effective in treating toxic effluents and reducing toxicity. However, the ultrasonic treatment is highly energy intensive since sonication is relatively inefficient with respect to total input energy and is therefore not economically attractive or feasible alone. Hence, sonochemistry has not yet received much attention as an alternative for industrial and large-scale chemical and environmental processes. One of the most interesting topics in the recent advances in sonochemistry is the possibility of double or more excitations with ultrasound and other types of energy. The coupling of ultrasound with other free energy sources (i.e., UV) or chemical oxidation utilizing H2O2, O3, or ferrous ion presents interesting and attractive approaches. Therefore, many recent efforts have been devoted to improving the efficiency of sonochemical reactions by exploiting the advantages of combinative or hybrid processes involving the simultaneous or sequential use of ultrasonic irradiation and other advanced oxidation processes, electrochemical processes, and biological treatment. This paper provides a critical review of the applications of ultrasound in environmental remediation, focusing on recent developments and unifying analysis of combinative or hybrid systems, namely, sonophotochemical oxidation processes.     

Direct evidence for destruction of polychlorobiphenyls by OH radicals in the subtropical troposphere

Although laboratory studies have indicated that OH radicals readily oxidize polychorobiphenyls (PCBs) in the gas-phase, this mechanism has never been positively demonstrated under real atmospheric conditions. By applying elaborated sampling and analytical techniques we achieved for the first time simultaneously a field study of the diurnal atmospheric cycle of OH radical and PCBs in a remote site of eastern Mediterranean. In all cases, the concentration of sigmaPCB (sum of 27 congeners) showed a characteristic depletion during daytime, while the concentration of OH radicals was at the maximum levels. By assuming that the depletion of PCBs was caused solely by the destruction from OH radicals, PCB-OH rate constants (KOH) of different PCB congeners were determined from field data by applying the relative rate method. Our field-determined KOH values were notably coherent with those previously measured in laboratory experiments. In all measurement periods, the KOH values consistently decreased in sequence for those compounds showing an increasing degree of chlorination on the biphenyl group. By taking into account KOH values and latitude-dependent concentration of OH radicals, it was estimated that, near to tropical and subtropical regions, the atmospheric lifetimes of PCBs 8 and 110 should be substantially low (10 and 20 days, respectively). A significant fraction of PCBs should be destroyed during their residence over tropical/subtropical regions, due to the intensive destruction by OH.     

Novel system for controlled investigation of environmental partitioning of hydrophobic compounds in water

Partitioning behavior of hydrophobic and semivolatile chemicals (such as many POPs and PAHs) in water is key in controlling their environmental distribution and fate. A new equilibrium method is presented here which allows determination of the equilibrium partition coefficient of hexachlorobenzene with suspended particle (K(SPM)≈ 337 L gOC(-1)) in a complex bulk water sample by correcting for a number of sampling artifacts and for the presence of dissolved matter. The method provides simultaneous experimental determination of the fraction of chemical truly dissolved in water (representing in this case about 54% of the bulk water concentration) and that associated to DM (21%). The Henry's law constant was also experimentally determined during the K(SPM) measurements, providing information on the occurrence of partitioning equilibrium in the system for each single observation. Results showed that the high level of quality control and accuracy provided confidence intervals for the K(SPM) estimates within 1 order of magnitude.     

A taxing environment: evaluating the multiple objectives of environmental taxes

Environmental taxes have attracted attention in recent years as a tool to internalize environmental externalities. This paper evaluates Sweden's experience with environmental taxes in the energy sector by examining how environmental taxes compare with estimated environmental externalities associated with the use of oil, coal, natural gas, and forest residue fuels. We also analyze how environmental taxes influence fuel choices in the energy sector by comparing the production, environmental, and tax costs for the same fuels. We find that (i) the Swedish environmental taxes correspond imperfectly with environmental costs; (ii) the Swedish tax and subsidy system introduces changes in fuel choice decisions; (iii) the energy users are responding to the incentives created by the tax and subsidy systems in ways that are consistent with economic theory; and (iv) the Swedish experience with environmental taxes and subsidies bears directly on wider evaluations of energy policy approaches internationally.     

电感耦合等离子体质谱法测定白酒中铅的前处理方法

目的探讨不同前处理方法对使用电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)测定白酒中铅含量检测结果准确性的影响。方法采用直接酸化稀释法、蒸干乙醇酸化稀释法和微波消解法分别对3份白酒样品及质控白酒样品进行前处理,使用10μg/L铋溶液作为在线内标,使用ICP-MS得到标准工作曲线后,测定白酒中的铅含量,并进行回收率实验。结果标准物质和加标回收率情况表明直接酸化稀释法处理的白酒样品铅平均含量偏低一些,但与其他2种方法相比差异不显著(P 0.05)。3种前处理方法对质控样品测定结果都在允许误差范围内。直接酸化稀释法存在一定的基体影响,蒸干乙醇酸化稀释法和微波消解法稳定性更好。结论蒸干乙醇酸化稀释法简化了白酒样品的前处理过程,减少了硝酸的用量,结果可靠,可在今后的检测工作中进行使用。     

组合分析法检测小麦粉中4种非法添加物

通过将酸碱度测试筛选、鲁米诺化学发光测试、灰分测试,以及灰分的X射线荧光全元素分析(XRF)和X射线晶体衍射分析(XRD)等多种分析测试技术组合运用,建立了小麦粉中过氧化钙、大白粉、石膏粉和滑石粉等4种非法添加物的鉴别与测定方法。试样经酸碱度测试即可基本判断待测物的种类,经鲁米诺发光反应测试其是否具有氧化性,进一步通过灰化富集待测物后,经XRF测试其所含主要元素,最终通过XRD确证待测物结构。根据分析方法和仪器测试灵敏度,确定小麦粉中过氧化钙、大白粉、石膏粉和滑石粉等4种非法添加物的半定量限值分别为0.05%,0.5%,0.5%,2%。该方法操作简单,快速准确,可以根据实际需要进行组合运用分析。