粉尘云最小点火温度测试实验系统设计

通过对Godbert -Greenwald恒温炉分析与改造 ,设计了粉尘云最小点火温度实验装置 ,并建立了相应的测试系统。调试结果表明 ,该实验系统扬尘均匀性、温控精度及结果可重复性能良好     

Effect of sorbed and desorbed Zn(Ⅱ) on the growth of a green alga (Chlorella pyrenoidosa)

Toxic effect of Zn(Ⅱ) on a green alga (Chlorella pyrenoidasa) in the presence of sepiolite and kaolinite was investigated.The Zn-free clays were found to have a negative impact on the growth of C.pyrenoidosa in comparison with control samples (without adding any clay or Zn(Ⅱ)).When Zn(Ⅱ) was added,the algae in the presence of clays could be better survived than the control samples,which was actually caused by a decrease in Zn(Ⅱ) concentration in the solution owing to the adsorption of Zn(Ⅱ) on the clays.When the solution system was diluted,the growth of algae could be further inhibited as compared to that in a system which had the same initial Zn(Ⅱ) concentration as in the diluted system.This in fact resulted from desorption of Zn(Ⅱ) from the zinc-contaminated clays,although the effect varied according to the different desorption capabilities of sepiolite and kaolinite.Therefore the adsorption and desorption processes of Zn(Ⅱ) played an important part in its toxicity,and adsorption and desorption of pollutants on soils/sediments should be well considered in natural eco-environmental systems before their risk of toxicity to aquatic organisms was assessed objectively.     

Adsorption of Cu（Ⅱ） on rice straw char from acidic aqueous solutions

研究了稻草炭对Cu（Ⅱ）的吸附特征,探讨了Cu（Ⅱ）的吸附机制.结果表明,稻草炭对Cu（Ⅱ）有很高的吸附容量,Langmuir方程能很好地拟合Cu（Ⅱ）吸附等温线,因此可以描述稻草炭对Cu（Ⅱ）的吸附,其预测的Cu（Ⅱ）在pH 4.5和pH 5.0时的最大吸附量分别为0.628 mol.kg-1和0.763 mol.kg-1.稻草炭对Cu（Ⅱ）的吸附量随体系pH升高而增加,但吸附Cu（Ⅱ）的解吸率呈相反的变化趋势.当吸附体系pH≤4.5时,Cu（Ⅱ）解吸率大于55%,说明此时以静电吸附为主;在较高pH条件下Cu（Ⅱ）以非静电吸附机制为主.红外光谱的分析结果表明,稻草炭表面有丰富的—COOH和—OH等含氧官能团,Cu2＋与含氧官能团形成有机络合物导致—COOH吸附峰位移.Cu（Ⅱ）吸附使稻草炭颗粒的Zeta电位向正值方向位移.结果说明Cu（Ⅱ）在稻草炭表面发生了专性吸附.     

Managing the cooling capacity of the upper rhine: A case study

In most industrialized countries, environmental standards exist which prescribe the maximum allowable man-made increase in water temperature of a river. Together with flowrate and weather conditions, these standards determine the rate at which waste heat may be discharged into a river at any moment. Power generating stations with variable cooling systems can adjust their heat discharge into the river in compliance with environmental standards and by doing so exert an influence on power generation capacity. In this paper, a scheme is developed that allows a chain of power stations discharging into the same river to operate their cooling systems such that the output of total electricity is maximized and water temperature standards are accomodated. The optimum balance between stations is determined through dynamic programming. From the results of a simulation model using historical data, simple decision rules for day-to-day operation are abstracted. These rules are based solely on the river flow rates at each power station.     

Rate-Limited Desorption of Volatile Organic Compounds from Soils and Implications for the Remediation of a Louisiana Superfund Site

The rates of desorption of trichloroethylene (TCE) and 1,3-dichlorobenzene (DCB) from a silty soil at a Superfund site and a silty-clayey soil from an uncontaminated bottomland hardwoodswamp in Baton Rouge, Louisiana were studied in laboratory batchsystems. The effect of the age of soil contamination was studiedusing a laboratory-spiked soil incubated for 3 days, 3 months and5 months. An empirical non-linear model was used to describe thebi-phasic nature of desorption with one fraction (labile) beingreleased in relatively short periods of time (typically 24–100 hr) and a second fraction (non-labile or irreversible) beingresistant to desorption. The non-linear model parameters, viz.,the fraction of the chemical released rapidly (F), and the firstorder desorption rate coefficients, k ₁ and k ₂respectively for the labile and slowly released fractions weredetermined by fitting the experimental data to the model. Thedata fit the model well as indicated by the high r ² values.The estimate of k ₁ was good. However, the values of k ₂are known with less precision due to the limited duration of theexperiment and number of samples taken at long times. In addition, desorption kinetics of 3 and 5-month old contaminatedsoils showed that progressively less amount of contaminant was available for facile desorption (lower F) compared to freshly contaminated soil. The labile fraction had desorption rate constants of the order of 10^-1 h^-1, whereas the slowlyreleased fraction had rate constants of the order of 10^-4 h^-1 in accord with literature reported values for a varietyof other compounds and soils. Possible mechanisms describing these rates and implications for the site clean up are discussed.     

Respiratory Suspended Particulate (RSP) Concentration and its Implications to Roadside Workers: A Case Study of Hong Kong

The adsorption behaviour of Diphenylamine (DPAM), napthylamine ( NAM), napthylamine ( NAM)and aniline on pyrolusite and activated carbon has been studied.Pyrolusite shows remarkable sorption capacity for DPAM and NAM as compared to aniline; (the adsorption followed theorder:Activated Carbon: DPAM = NAM > AnilinePyrolusite: DPAM: NAM > NAM> Aniline)The maximum adsorption of NAM occurred in theconcentration range 4–20 g mL^-1 on pyrolusite (95%)and 4–50 g mL^-1 on activated carbon (100%). Theeffect of various doses of activated carbon on the adsorption of NAM confirm Langmuir and Freundlich isotherms where asFreundlich isotherm is obeyed by pyrolusite. The adsorption of NAM on both the absorbents is not affected in presence ofDPAM over a wide range of their initial concentrations (20–60g mL^-1). The desorption studies of NAM onpyrolusite was carried out by batch as well as column processes.Excellent results were obtained when a mixture of n-hexane andisopropanol (91:1) was used as eluent.     

Partition Constants and Adsorption/Desorption Hysteresis for Volatile Organic Compounds on Soil from a Louisiana Superfund Site

The adsorption of four volatile organic compounds (1,4-dichloro-benzene, 1,2-dichloroethane, 1,2,2-trichloroethane and 1,1,2,2,-tetrachloroethane) on three soil types from a Superfund site (Petroprocessors Inc) in Baton Rouge, LA was studied with the purpose of obtaining an overall correlation for inclusion in a groundwater transport model being developed for site remediation. The soil-water partition constant, K_d was determined using a standard ASTM procedure (E–1195–87). Using the data for different soil types (fraction organic carbon between 0.11% and 1.13%) and different mineral surface areas (7 to 45 m²/g), the organic carbon contribution (K_oc) and the mineral matter contribution (K_min) to the partition constant were determined. The soils obtained were either from the Pleistocene period or recent shallow deposits at the site. Both log K_oc and log K_min were linearly correlated to log K_ow, the octanol-water partition constant. This data provided the basis for obtaining a general correlation for K_d on different soil types at the site. The predicted values were in agreement with that for a composite soil from the same site. The desorption of compounds from the high clay soil after the 24 hour adsorption period was observed to show a biphasic behavior, namely, an easily desorbed fraction and a desorption resistant fraction. The easily desorbed fraction was found to be satisfactorily predicted using the conventional K_d as obtained from the adsorption experiment. The slowly desorbing fraction had a time constant of several weeks. The concentration in the desorption resistant compartment was found to be dependant on the initial amount of contaminant available for adsorption. The aqueous phase concentration in equilibrium with the desorption resistant fraction was found to be 8 g/L for dichlorobenzene and 12 g/L for dichloroethane.     

Thermal internal boundary layer and its effects on air pollutants during summer in a coastal city in North China

The thermal internal boundary layer(TIBL) is associated with coastal pollution dispersion,which can result in high concentrations of air pollutants near the surface of the Earth. In this study, boundary layer height data which were obtained using a ceilometer were used to assess the effect of the TIBL on atmospheric pollutants in Qinhuangdao, a coastal city in North China.A TIBL formed on 33% of summer days. When a TIBL formed, the sunshine duration was 2.4 hr longer, the wind speed was higher, the wind direction reflected a typical sea breeze, and the boundary layer height was lower from 9:00 LT to 20:00 LT compared to days without a TIBL. If no TIBL formed, the average concentrations of PM_(2.5) and PM_(10) decreased with increasing boundary layer height. However, when a TIBL was observed, the average concentrations of PM_(2.5) and PM_(10) increased with increasing boundary layer height. Because the air from the sea is clean, PM_(2.5) and PM_(10) concentrations reached minimums in the daytime at 16:00 LT. After16:00 LT, the PM_(2.5) and PM_(10) concentrations increased rapidly on days when a TIBL formed,which indicated that the TIBL leads to the rapid accumulation of atmospheric pollutants in the evening. Therefore, the maximum concentrations of particulate matters were larger when a TIBL formed compared to when no TIBL was present during the night. These results indicate that it is suitable for outdoor activities in the daytime on days with a TIBL in coastal cities.     

Destratification and oxygenation efficiency of a water-lifting aerator system in a deep reservoir: Implications for optimal operation

Thermal stratification is a common phenomenon in lakes and reservoirs and has a significant influence on water quality dynamics.Heihe Reservoir is a canyon-shaped reservoir in Shaanxi Province with strong thermal stratification.Therefore,eight water-lifting aerators(WLAs) were installed in this reservoir,which could overcome thermal stratification and increase oxygenation with gas flows between 20 and 50 m3/hr,and oxygenate the hypolimnion with gas flows less than 20 m3/hr.To examine the destratification efficiency of the WLA system,we used a threedimensional hydrodynamic module based on MIKE 3 to simulate the thermal structure of Heihe Reservoir and compared the simulations with measured data.Results showed that operation of the WLA system promoted water mixing and effectively oxygenated the hypolimnion.Through the established energy utilization assessment method,the energy utilization efficiency of the WLA system was between 5.36% and 7.30%,indicating the capability of the technique for destratification in such a large reservoir.When the surface water temperature dropped to the theoretical mixed water temperature calculated by the energy utilization assessment method,reducing gas flow could save energy.This would prevent anaerobic conditions from occurring in the bottom water and maintain good water quality in Heihe Reservoir.     

Cu2+存在下腐殖酸对磺胺嘧啶吸附解吸的影响

为探究重金属与抗生素共存时不同条件下土壤有机组分对抗生素吸附解吸的影响,通过批量静态吸附试验方法,研究了不同污染物浓度、初始pH、离子强度及阳离子类型下腐殖酸对磺胺嘧啶（sulfadiazine）和重金属Cu共存时吸附解吸行为及其交互作用,并做了显著性差异分析;采用Freundlich、Langmuir等温吸附模型和线性等温吸附模型对试验数据进行拟合,对吸附前后的样品进行红外光谱扫描分析.结果表明:①不同w（Cu2+）对腐殖酸吸附磺胺嘧啶的状况不同,当w（Cu2+）为1、10、100 mg/kg时,Cu2+的存在起促进吸附的作用;当w（Cu2+）为300 mg/kg时,Cu2+的存在起抑制吸附的作用;随着初始pH的增大,吸附量变化不明显,但略有减小;高离子强度促进吸附,低离子强度抑制吸附;高价态阳离子的存在抑制腐殖酸对磺胺嘧啶的吸附.②显著性差异分析显示,P均小于0.05,说明w（Cu2+）、pH、离子强度及阳离子类型对吸附量均有显著影响.③运用Freundlich、Langmuir等温吸附模型和线性等温吸附模型对不同条件下的吸附特征进行拟合,其拟合效果均较好,R2均大于0.952,其中线性等温吸附模型拟合效果最好;HI（滞后系数）在0.995~1.120之间,接近于1,表明腐殖酸对磺胺嘧啶的吸附解吸过程中不存在滞后现象.△G（吉布斯自由能变化量）在18.921~20.412 kJ/mol之间,均小于40 kJ/mol,属于物理吸附.④红外光谱分析表明,腐殖酸对磺胺嘧啶的吸附机制主要是形成氢键或发生络合反应.研究显示,不同条件下腐殖酸对磺胺嘧啶吸附解吸的影响不同,w（Cu2+）、初始pH、离子强度及阳离子类型的改变,均会导致腐殖酸对磺胺嘧啶的吸附情况有所差异.