COD快速测定法

以用时30min的半微量密闭微波消解法取代COD国标测定中的重铬酸钾回流法,改进后的方法精密度小于5．15％,准确度达到102％,COD测定下限为51mg／L。该法节省时间、取样量少、成本低,适用于大批量水样的快速测定。     

电凝聚-气浮法处理印染废水

采用电凝聚-气浮法处理模拟印染废水（简称废水）,考察了废水pH、电解电流、电解时间对废水COD去除率的影响。实验结果表明,当废水pH=6．5、电解电流为1．0A、电解时间为25min时,废水COD去除率可达90％以上。该方法具有较宽的操作范围,电解电流为1．0～1．9A,废水COD去除率相差不大;废水pH为3.45～11.46,废水COD去除率均可达80％以上。电凝聚-气浮法处理印染废水无需外加药剂,无二次污染。     

含高氯化钙环氧化合物废水COD的测定

硫酸汞标准法不能有效地消除Cl-对COD测定的影响,其COD测定的相对误差大,测定结果的重复性差。硝酸银法有效地消除Cl-对COD测定的影响,其COD测定的相对误差为—4—8％,测定结果的重复性好、精密度高,变异系数为10％。     

高氯化物废水中COD测定方法的研究

对COD测定的重铬酸钾标准法加硫酸汞除氯的诸因素进行了研究,提出了用KI吸收校正法解决氯化物的干扰。采用KI吸收校正法可准确测定高氯化物废水中COD含量,当COD≥100毫克/升,Cl≤20000毫克/升时,方法相对误差为3.5％,变异系数为±4.9％,实际废水变异系数为±4.2％。     

在氧化沟中构建微生物燃料电池

在氧化沟中构建了微生物燃料电池,经测定微生物燃料电池电压为0.24～0.39 V,均值为0.29 V.经计算该微生物燃料电池的产电功率为0.05～0.15 mW,均值为0.08 mW.构建了微生物燃料电池的氧化沟COD去除率为75％～ 90％,TN去除率为5％～38％;无微生物燃料电池的氧化沟COD去除率为77％～89％,TN去除率为5％～23％.构建微生物燃料电池后能减少氧化沟内外沟中污泥的增加量,约减少15％.     

用硝酸银消除高浓度氯离子对COD测定的干扰及测定废液中银的回收

分析了氯离子的干扰机理，提出了用硝酸银代替硫酸汞消除氯离子干扰测定高氯离子水样COD的分析方法，同时对COD废液的处理及废液中银的回收利用进行了研究。实验结果表明，该法具有较好的准确性和重复性，其相对误差均在国家规定的允许范围内；COD废液中的银经分离后，用Zn—H2SO4体系还原回收，银回收率为94．8％，回收的银粉纯度为99．6％，且可实现COD废液中银的循环使用。     

Fenton氧化-生物接触氧化工艺处理甲醛和乌洛托品废水

采用Fenton氧化一生物接触氧化工艺处理含甲醛和乌洛托品的模拟废水（简称废水），在H2O2（体积分数30％）加入量2．5g／L、H2O2与Fe^2＋质量浓度比3．75、反应时间3h、不调节废水初始pH的Fenton氧化预处理最佳操作条件下，废水COD从1000mg／L左右降至300mg／L，COD去除率达72％。原废水完全无法直接进行生化处理，经Fenton氧化预处理后其BOD，／COD约为0．5，易于生化处理。Fenton氧化一生物接触氧化工艺处理废水，生物接触氧化停留时间为12h时，废水COD去除率高达94％，处理后出水COD小于70mg／L，处理效果很好。     

含氯苯和对邻硝基氯苯农药废水的混凝一氧化预处理

采用混凝沉淀－芬顿试剂对氧化对含氯苯和对邻硝基氯苯农药废水进行预处理，探讨了不同条件下农药废水的处理效果。结果表明：废水经混凝处理后可去除46．2％的COD，BOD5／COD值有一定程度的提高；废水经芬顿试剂氧化处理后可去除50．9％的COD，BOD5／COD值可从0．04提高到0．16。     

絮凝沉淀-Fenton试剂氧化法处理含高浓度硫酸盐的洗涤剂生产废水

采用絮凝沉淀-Fenton试剂氧化法处理含高浓度硫酸盐的洗涤剂生产废水（简称废水），考察了各种因素对COD去除率的影响。实验结果表明：根据实际废水的水质情况，选用聚合氯化铝（PAC）为絮凝剂，PAC最佳加入量为0．3g／L，经絮凝处理后COD去除率为42．3％；Fenton试剂氧化的最佳操作条件为：n（H2O2）：n（Fe^2＋）=0．5、H2O2加入量为7mmol／L、反应时间为2h，不调节废水初始pH，经Fenton试剂氧化处理后COD去除率为70％以上。经絮凝沉淀-Fenton试剂氧化法处理后，废水COD由1950mg／L降至240mg／L，总的COD去除率为87．7％，废水处理效果良好。     

高压脉冲放电-臭氧氧化处理活性艳红K-2BP废水

自制电压为10kV的高压脉冲放电反应器，对质量浓度为200mg／L的模拟活性艳红K-2BP废水进行脱色和去除COD实验。实验结果表明：通氧气高压脉冲放电与高压脉冲放电相比，废水脱色率提高了1．3％，约为6％，COD去除率提高了3％，达14％；高压脉冲放电协同臭氧氧化与臭氧氧化相比，反应初期废水脱色率提高了约10％，反应30min后废水脱色率均达99％以上，COD去除率提高了15．2％，达80％。向废水中加入Na2CO3可使COD去除率明显下降；加入NaCl，在臭氧氧化条件下，COD去除率由66．86％降至58．86％；而加入Na2SO4后COD去除率升至81．70％。     

Review of the kinetics of alkaline degradation of cellulose in view of its relevance for safety assessment of radioactive waste repositories

The degradation of cellulose (a substantial component of low- and intermediate-level radioactive waste) under alkaline conditions occurs via two main processes: a peeling-off reaction and a basecatalyzed cleavage of glycosidic bonds (hydrolysis). Both processes show pseudo-first-order kinetics. At ambient temperature, the peeling-off process is the dominant degradation mechanism, resulting in the formation of mainly isosaccharinic acid. The degradation depends strongly on the degree of polymerization (DP) and on the number of reducing end groups present in cellulose. Beyond pH 12.5, the OH^- concentration has only a minor effect on the degradation rate. It was estimated that under repository conditions (alkaline environment, pH 13.3-12.5) about 10% of the cellulosic materials (average DP = 1000-2000) will degrade in the first stage (up to 10⁵ years) by the peeling-off reaction and will cause an ingrowth of isosaccharinic acid in the interstitial cement pore water. In the second stage (10⁵-10⁶ years), alkaline hydrolysis will control the further degradation of the cellulose. The potential role of microorganisms in the degradation of cellulose under alkaline conditions could not be evaluated. Proper assessment of the effect of cellulose degradation on the mobilization of radionuclides basically requires knowing the concentration of isosaccharinic acid in the pore water. This concentration, however, depends on several factors such as the stability of ISA under alkaline conditions, sorption of ISA on cement, formation of sparingly soluble ISA-salts, etc. A discussion of all the relevant processes involved, however, is far beyond the scope of the presented overview.     

Study of Aging Characteristics of Ternary Blends of Polyethylenes—II

Six film samples of low-density polypropylene (LDPE)/linear LDPE (LLDPE)/high-density polypropylene (HDPE) with varying ratios of LDPE (20–45 ... wt%) and LLDPE (25–50 wt%) having a fixed amount of HDPE at 30 wt% were prepared by blown film extrusion technique. The samples were aged at four different temperatures, 55°, 70°, 85°, and 100°C, for four different time periods in the interval of between 150 hours and up to 600 hours. The change in the structure of various constituents and the formation of various oxygenated (peroxy and hydroperoxy) and unsaturated groups during thermo-oxidative degradation was discussed by infrared spectroscopy. The visiosity-average molecular weight was found to have decreased slowly in the initial aging hours and temperatures, whereas it decreased by 10% with its previous value tensile strength that is, 100°C when aged for 600 hours. The tensile strength of the sample first increased by 67% at 55°C and 89% at 70°C up to 450 hours, whereas the values increased by 52.5% at 85°C and 33.9% at 100°C when aged for 150 hours and then decreased. The percentage elongation at break increased by 2.7% at 55°C and 10.7% at 70°C for 150 and 300 hours of aging, respectively, whereas the percentage decreased when aged at 85°C and 100°C for up to 600 hours of aging. The values of gel content (percent) increased and initial degradation temperature decreased with aging time and temperature.     

Calculation of carbon balances for evaluation of the biodegradability of polymers

Establishing carbon balances has been proven to be an applicable and powerful tool in testing biodegradability of polymers. In controlled degradation tests at a 4-L scale with the model polymer poly(-hydroxybutyrate) (PHB), it was shown that the degree of degradation could not be determined with satisfactory accuracy from CO₂ release alone. Instead, the course of degradation was characterized by means of establishing carbon balances for the degradation of PHB withAcidovorax facilis and a mixed culture derived from compost. Different analytical methods for determining the different carbon fractions were adapted to the particular test conditions and compared. Quantitative determination of biomass and residual polymer were the main problems in establishing carbon balances. Amounts of biomass derived from protein measurements depend strongly on assumptions of the protein content of the biomass. Selective oxidation of biomass with hypochlorite was used as alternative, but here problems arose from insoluble metabolic products. Determination of soluble components with the method of chemical oxygen demand (COD) also includes empirical assumptions but seems acceptable if the dissolved carbon fraction is in the range of some 10% total carbon. Results confirm both analytical assays and theoretical approaches, in ending up at values very close to 100%, within an acceptable standard deviation range under test conditions comparable to standard test practice.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.     

Model of technological alternatives of production of sodium chromate (VI) with the use of chromic wastes

This article presents a mathematical model which describes the sodium chromate (VI) production process with the use of chromic waste as a substitution of natural raw materials. This model is a function of selected process parameters common for all of the examined alternatives and based on equations of material balance. Optimization of the elaborated technological alternatives of the production process with use of recycling of chromic waste has been evaluated by determining the extreme value of the quality indicator WJ. This indicator defines the quantity of waste created in the process. Optimization results enabled the selection of the optimal technological solution from all of the alternatives possible for use in industrial practice. Negative values of the indicator prove that there is the possibility of introducing to the process a larger quantity of waste than the one obtained in the process and transported to the storage heaps.     

Determination of the Burning Characteristics of a Slick of Oil on Water

The burning rate of a slick of oil on a water bed is characterized by three distinct processes, ignition, flame spread and burning rate. Although all three processes are important, ignition and burning rate are critical. The former, because it defines the potential to burn and the latter because of the inherent possibility of boilover. Burning rate is calculated by a simple expression derived from a one-dimensional heat conduction equation. Heat feedback from the flame to the surface is assumed to be a constant fraction of the total energy released by the combustion reaction. The constant fraction (χ) is named the burning efficiency and represents an important tool in assessing the potential of in situ burning as a counter-measure to an oil spill. By matching the characteristic thermal penetration length scale for the fuel/water system and an equivalent single layer system, a combined thermal diffusivity can be calculated and used to obtain an analytical solution for the burning rate. Theoretical expressions were correlated with crude oil and heating oil, for a number of pool diameters and initial fuel layer thickness. Experiments were also conducted with emulsified and weathered crude oil. The simple analytical expression describes well the effects of pool diameter and initial fuel layer thickness permitting a better observation of the effects of weathering, emulsification and net heat feedback to the fuel surface. Experiments showed that only a small fraction of the heat released by the flame is retained by the fuel layer and water bed (of the order of 1%). Ignition has been studied to provide a tool that will serve to assess a fuels ease to ignite under conditions that are representative of oil spills. Two different techniques are used, piloted ignition when the fuel is exposed to a radiant heat flux and flash point as measured by the ASTM D56 Tag Closed Cup Test. Two different crude oils were used for these experiments, ANS and Cook Inlet. Crude oils were tested in their natural state and at different levels of weathering, showing that piloted ignition and flash point are strong functions of weathering level.     

化学品生物降解性的评价与预测

介绍了有机化学物质生物降解性的测定方法及其预测方法研究概况，并讨论了生物降解性评价的发展前景。     

Mechanism of Microbial Degradation of Slow-Release Fertilizers

Methyleneureas are condensation products of urea and formaldehyde of different molecular mass and solubility; they are used in large amounts both as resins, binders, and insulating materials for industrial applications, as well as a slow-release nitrogen fertilizer for greens, lawns, or in bioremediation processes. In the present study, the microbial breakdown of these products was investigated. The nitrogen was released as ammonia and urea, and the formaldehyde released immediately oxidized via formiate to carbon dioxide. The enzymatic mechanism of metabolization of methyleneureas was studied in microorganisms isolated from soil, which were able to use these compounds as the sole source of nitrogen for growth. A strain of the Gram-negative bacterium Ralstonia paucula (formerly Alcaligenes sp. CDC group IVc-2) completely degraded methylenediurea and dimethylenetriurea to urea, ammonia, formaldehyde, and carbon dioxide. The enzyme initiating this degradation (methylenediurease) was purified and turned out to be different from the previously described enzyme from Ochrobactrum anthropi with regard to its regulation of expression and physicobiochemical properties. Fungal degradation of methyleneureas may occur via the formation of organic acids, thus leading to a nonenzymatic degradation of methyleneureas, which are unstable under acidic conditions.     

Effect of Degree of Substitution of Octenyl Succinate Starch on Enzymatic Degradation

Octenyl succinate starch of degree of substitution (ds) 0.03, 0.07, and 0.11 was synthesized in an aqueous medium. These compounds were then tested for the susceptibility to enzymatic degradation. The multiple-enzyme regime of -amylase, amyloglucosidase, and pullulanase was chosen for the evaluation. This combination of enzymes had been proven to degrade 99.5% of unmodified starch to glucose and hence was chosen for this study. It was found that even small amounts of subsituent caused a considerable decrease in the extent of degradation. The net extent of degradation decreased with increasing ds. Surprisingly, the amount of glucose from all three substituted substrates was quite similar, suggesting the effect small amounts of subtituent had on the enzymatic activity.     

Structure-biodegradation relationships of polymeric materials. 1. Effect of degree of oxidation on biodegradability of carbohydrate polymers

The biodegradability of oxidized starch and inulin has been studied in relation to the degree of periodate oxidation to dialdehyde derivatives, by measuring oxygen consumption and mineralization to carbon dioxide. A higher degree of oxidation of dialdehyde starch and dialdchyde inulin results in a lower rate at which the polymers are biodegraded. It is demonstrated that the biodegradation rate of dialdehyde inulin derivatives decreases more than that of equivalent starch derivatives. The differences in biodegradation behavior between dialdehyde starch and dialdehyde inulin, resulting from comparable modifications, are discussed in terms of conformational structure.     

鼓泡式反应器高径比对氨法烟气脱碳性能的影响

以N2和CO2混合气模拟燃烧烟气，研究了鼓泡反应器的高径比以及反应条件对氨法烟气脱碳性能的影响。实验结果表明:在相同高径比的条件下，CO2吸收率随氨水质量分数的增加、反应温度的升高而逐渐增大，随进气CO2体积分数和模拟烟气流量的增加而逐渐减小;CO2吸收率随高径比的增加而增大，在高径比为3.98、氨水质量分数为28%、进气CO2体积分数为10%、模拟烟气流量为1.0L/min、反应温度为40℃的条件下，CO2吸收率最高可达100%。