Trichloroethylene decomposition and in-situ dry sorption of Cl-products by calcium oxides prepared from hydrated limes

A comparison of CaOs produced by calcining two types of hydrated lime and calcium carbonate was made for decomposition of trichloroethylene and in-situ dry sorption of the decomposed Cl-products using a lab-scale gas flow type tubular packed bed reactor. About 20 mg of CaO sample was mixed with about 2 g of Al₂O₃ particles and packed in the reactor and allowed to react with a flowing standard gas containing 500 ppm of C₂HCl₃ (N₂ balance) at 673 and 873 K, under the condition that the reaction of CaO with C₂HCl₃ might be completed within a few hours.It was found that no thermal decomposition of C₂HCl₃ at or below 673 K was observed in a reactor packed only with Al₂O₃ particles. However, a considerable amount of decomposition of C₂HCl₃ was obtained in a reactor packed with CaO and Al₂O₃, even at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)₂ at 673 K, decomposition of 0.42 mol of C₂HCl₃ and in-situ absorption product of 0.53 mol of CaCl₂ were obtained. At 873 K, about 46% of C₂HCl₃ was thermally decomposed. The total amount of C₂HCl₃ decomposed in CaO-Al₂O₃ particle bed at 873 K became nearly twice larger than that at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)₂ at 873 K, decomposition of 0.59 mol of C₂HCl₃ and in-situ absorption product of 0.67 mol of CaCl₂ were obtained. Small amounts of C₂Cl₂, C₂Cl₄, CCl₄, etc. were detected during decomposition of C₂HCl₃ at 673 and 873 K.It was recognized that the data on decomposition of C₂HCl₃ as well as in-situ dry sorption of Cl-products in CaO particle bed were correlated with specific surface area of the CaO employed.     

THE LIMNOLOGY OF LAKE WABUKAYNE,A STORM-WATER IMPOUNDMENT1

ABSTRACT The limnology of a 1.9-ha storm-water detention pond is described. The eutrophic nature of this impoundment is attributed to the nutrients in runoff from the surrounding residential area. During the summer, photosynthetic activity of the phytoplankton caused surface waters to become super-saturated with oxygen, while decomposing organic material greatly reduced dissolved oxygen concentrations in the deeper water. Sediment derived from construction activity within the drainage basin caused the impoundment to be turbid. The use of road deicing salts within the drainage basin produced high chloride concentrations and a temporary meromixis during the winter and early spring. The benthic fauna consisted primarily of oligochaetes, chironomids, and chaoborids. High densities of oligochaetes were present in the settling basin. Chaoborid larvae were abundant in the deep basin where low oxygen concentrations reduced the numbers of other benthic macroinvertebrates.     

MATHEMATICAL MODELS: PLANNING TOOLS FOR THE GREAT LAKES1

The Great Lakes Basin Commission has initiated a Framework Study to assess the present and projected water- and related land-resource problems and demands in the Great Lakes Basin. Poorly defined objectives; incomplete and inconsistent data arrays; unknown air, biota, water, and sediment interactions; and multiple planning considerations for interconnected, large lake systems hinder objective planning. To incorporate mathematical modeling as a planning tool for the Great Lakes, a two-phase program, comprising a feasibility and design study followed by contracted and in-house modeling, data assembly, and plan development, has been initiated. The models will be used to identify sensitivities of the lakes to planning and management alternatives, insufficiencies in the data base, and inadequately understood ecosystem interactions. For the first time objective testing of resource-utilization plans to identify potential conflicts will provide a rational and cost-effective approach to Great Lakes management. Because disciplines will be interrelated, the long-term effects of planning alternatives and their impacts on neighboring lakes and states can be evaluated. Testing of the consequences of environmental accidents and increased pollution levels can be evaluated, and risks to the resource determined. Examples are cited to demonstrate the use of such planning tools.     

Linear free energy relationships for dechlorination of aromatic chlorides by Pd/Fe

Reductive dechlorination rate constants for five chlorobenzenes in the presence of Pd/Fe as catalyst were determined experimentally. Linear free energy relationships (LFER) for the dechlorination rate constants of five chlorobenzenes and three chlorophenols were developed by partial least squares (PLS) regression based on quantum chemical parameters computed by PM3 Hamiltonian. The optimal LFER model obtained is

logk=−1.63+1.46×10⁻³ΔH_f−7.69×10⁻¹E_LUMO

where k stands for the dechlorination rate constants, ΔH_f is the standard heat of formation, and E_LUMO is the energy of the lowest unoccupied molecular orbital. The Q²_cum value of the model is 0.879, indicating good robustness and predictive power of the model.     

氯化物排放标准的制定

河北省是工业大省,一些企业生产过程排放的污水中含大量的氧化物,由于目前国家没有制定相应的排放标准,造成企业在排污过程中无限制地排放,直接影响了水环境质量。河北省为加强地方流域的水环境管理,依法限制污染物的排放,提出了河北省特征污染物氯化物地方排放标准的制定原则、方法和基本思路。     

流动注射分光光度法测定水中的氯离子

本文采用流动注射分析（ＦＩＡ）技术．载流中含有Ｈｇ（ＳＣＨ）２和Ｆｅ２＋，注入试样中的氯离子与Ｈｇ（ＳＣＨ），反应，释放出ＳＣＨ－，后者与Ｆｅ２＋形成红色Ｆｅ（ＳＣＨ）给离子，其强度用分光光度法在４８０ｎｍ处测定．记录的吸收峰高度与试样中氯离子浓度成正比．线性范围６．０—１８μｍ／ｍＬＣｌ，检出限达０．１２μｇ／ｍＬＣｌ－．对６．０μｇ／ｍＬＣｌ－连续测定１１次，其ＲＳＤ为３．９％．出样频率为９０样／小时．方法已用于水样中氯离子的测定．     

痕量有机氯化合物分析中的样品预处理方法

近些年来，痕量有机氯化合物分析中，各种样品预处理技术得到了迅速发展，文章介绍了一些样品预处理方法的原理和最新进展，阐述了索氏提取，超临界流体萃取，微波萃取，固相萃取等几种富集方法的原理，特点，性能及应用，论述了吸附柱层析法，凝胶渗透色谱，高效液相色谱等样品净化技术的特点和应用。     

环境样品中有机氯化合物的监测分析

有机物对环境的污染日益受到各国的关注,尤其是多氯代二苯并－ｐ－二类（ＰＣＤＤｓ）、多氯代二苯呋喃（ＰＣＤＦｓ）和ＰＣＢｓ等。在我国新修订的“污水综合排放标准”中,也增加了许多有机氯化物项目;本文就二类等有机氯化物的环境监测分析方法作以概括介绍。     

焚烧飞灰高温过程中重金属的挥发及其氯转化特征

研究了垃圾与污泥掺烧后的焚烧飞灰在900℃、1 000℃高温处置过程中重金属(Cu、Zn、Pb、Cd)随不同停留时间的挥发特性,并研究了添加剂氯化物(CaCl2、MgCl2、NaCl、FeCl3、AlCl3)对重金属转化与挥发特性的影响.结果表明,没有添加氯化剂情况下,污泥焚烧飞灰中不同重金属的挥发特性有较大的差别,其中Pb的挥发率超过80%,而Cu的挥发率<30%,重金属的挥发性大小依次为:Pb>Cd>Zn>Cu.热处置过程中重金属的挥发率受温度的影响较大,而停留时间的延长对重金属挥发促进效果较小,并且易挥发元素Pb和Cd表现尤为明显.飞灰中添加氯化剂后,重金属的挥发性有显著的改变,并且难挥发元素Cu和Zn的挥发性增加较Pb和Cd显著.随着Cl含量的增加,重金属挥发率有增加的趋势,但不同种类的氯化物对重金属氯转化差异较大,其中NaCl对重金属Cd、Zn和Cu挥发特性的促进效果小于其它氯化剂.研究结果为飞灰最大限度无害化处理及资源化回收利用提供理论依据.     

ECONOMICS OF CONTROLLING NATURAL SALT SOURCES IN THE ARKANSAS RIVER BASIN1

ABSTRACT: The methodology underlying, and the estimates incorporated in the Corps of Engineers' economic evaluation of the Arkansas River Basin Chloride Control Project are evaluated and judged deficient in several ways. An improperly specified alternative cost analysis probably results in overestimates of the total regional demand for water, the demand for Arkansas River Water, and the cost-savings realized with the project in place. The quantitative effect of these errors is not determined. However, other adjustments are identified which are evaluated using the Corps' data. These adjustments reduce B/C from 2.64 to 0.57; principally as a result of corrections for over-estimates of cost-savings in steam-electric generation, and for use of improper discounting procedures and gross output-earnings ratios.