絮凝-电解氧化联合处理氰化提金废水

采用絮凝-电解氧化联合技术处理氰化废水,主要研究了聚硅酸铝铁 (PSAF) 添加量、絮凝时间、pH、电压、电解时间、极板间距对总氰(CN_T)、游离氰(CN⁻)、Cu、Zn离子去除率的影响,并对其反应机制做了分析。研究表明,当PSAF添加量为2 g·L⁻¹,絮凝时间为30 min,pH为9条件下,CN_T、CN⁻、Zn、Cu离子的去除率分别可达42.97%、100%、84.40%、34.88%。Zn(CN)₄²⁻、Cu(CN)₃²⁻、CN⁻的吸附量分别为567.88、89.76、439.74 mg·L⁻¹。以钛板为阴极,石墨板为阳极,采用一阴两阳体系对絮凝后液进行电解氧化实验,在电压为3 V、电解时间为2 h、极板间距为10 mm条件下,CN_T、CN⁻、Zn、Cu离子的去除率可达91.70%、100%、99.15%、94.49%。絮凝过程中Zn(CN)₄²⁻、Cu(CN)₃²⁻、CN⁻的去除是由电荷中和和化学吸附共同作用的,其中电荷中和起主要作用。Zn(CN)₄²⁻、Cu(CN)₃²⁻、CN^-的化学吸附主要归因于其与PSAF水解产生的羟基阳离子发生交换反应。XRD分析表明,加入酸性絮凝剂PSAF的瞬间,部分Zn(CN)₄^2-反应为Zn(CN)₂沉淀。电解氧化过程中Zn(CN)₄²⁻、Cu(CN)₃²⁻破络释放的氰根会被阳极表面产生的O₂、·OH完全氧化为N₂和CO₂,Zn、Cu离子在阴极板电沉积而被去除。     

化学事故救援方舱舱室环境安全性模拟研究

运用计算流体动力学(CFD)方法,对具有超压防护功能的某化学事故应急救援手术方舱室内气体污染物运动扩散的规律以及对人员安全的影响进行了数值模拟,其研究结果表明:当大气环境中氢氰酸(HCN)浓度为5 mg/L时,前10 s从常规进风口进入舱室的HCN在滤毒通风装置开启后,随气流运动逐渐向整个舱室扩散,经净化空气的混合稀释作用,绝大部分通过舱体缝隙排出舱室,30 min内舱室HCN浓度的总量下降了95.1%,说明超压防护很好地保证了舱室环境的安全性.     

Kinetic-spectrophotometric determination of free cyanide by stopped-flow reversed flow injection analysis

A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.     

Detoxification of ferrocyanide in asoil–plant system

The detoxification of iron cyanide in a soil–plant system was investigated to assess the total cyanide extracted from contaminated soil and allocated in the leaf tissue of willow trees(Salix caprea). They were grown in soil containing up to 1000 mg/kg dry weight(dw) of cyanide(CN),added as ~(15)N-labeled potassium ferrocyanide and prepared with a new method for synthesis of labeled iron cyanides. CN content and ~(15)N enrichment were monitored weekly over the exposure in leaf tissue of different age. The ~(15)N enrichment in the young and old leaf tissue reached up to 15.197‰ and 9063‰, respectively; it increased significantly over the exposure and with increasing exposure concentrations(p 0.05). Although the CN accumulation in the old leaf tissue was higher, compared to the young leaf tissue(p 0.05), the ~(15)N enrichment in the two tissue types did not differ statistically. This indicates a non-uniform CN accumulation but a uniform ~(15)N allocation throughout the leaf mass. Significant differences were detected between the measured CN content and the C~(15)N content, calculated from the ~(15)N enrichment(p 0.05), revealing a significant CN fraction within the leaf tissue, which could not be detected as ionic CN. The application of labeled iron CN clearly shows that CN is detoxified during uptake by the willows. However, these results do not exclude other detoxification pathways, not related to the trees. Still, they are strongly indicative of the central role the trees played in CN removal and detoxification under the experimental conditions.     

Heavy metal analysis in fish‐kill cases in rivers in Guipuzcoa (Spain)∗

Some fish‐kills in Basque rivers were studied by gill tissue analysis: Samples were wet digested and the solution was analyzed by atomic absorption spectroscopy. In three cases, the cause was linked to the effluents of an aluminium anodizing factory, cyanide caused one kill and copper wastes were related with another. Three cases were attributed to natural reasons and one of the kills was of unknown origin.     

胶束增敏光度法测定微量氰化物的研究

根据CN^-对丁二酮肟-Ni-曲通X-100体系的增色作用，建立了一种测定微量氰化物的新方法。方法选择性好，操作简便，不需要蒸馏和萃取。CN-含量在0-0．32mg／L内符合比耳定律，用于环境水中氰化物的测定，结果满意。     

高炉煤气洗涤水氰化物产生及控制对策探讨

通过分析高炉煤气洗涤水氰化物的产生机理,探讨了湘钢1#高炉煤气洗涤水氰化物超标的主要原因,结合高炉煤气洗涤水处理氰化物的治理现状,提出了相应的治理对策.     

Bhopal gas tragedy: scientific challenges and lessons for future

Some of the challenges of BGT were answered by two multi-disciplinary projects of the ICMR on Pathology and Toxicology and Pathophysiology. Unlike other chemical disasters, the aerosol inhaled by the Bhopal victims contained a mixture of MIC and its trimers and dimers, as well as aqueous and thermal decomposition products, including HCN. A coordinated GC–MS study of the blood and autopsy tissues and chemicals in the Tank residue confirmed their role.

Autopsy studies revealed the pathological changes in the acute, sub-acute and chronic phases progressive changes of pulmonary edema and bronchiolitis, followed by chronic pulmonary fibrosis. Cerebral edema resulted in ‘acute histotoxic anoxia’. Intensive experimental studies with the help of newer tools of molecular biology might throw more light on the underlying mechanisms and newer therapeutic approaches.

The initial finding of cherry-red discoloration of lungs led to a suspicion of cyanide toxicity. Eventually, elevated blood and tissue cyanide levels confirmed the prompt therapeutic response to NaTS and accompanying increase of urinary NaSCN excretion. However, periodic clinical recurrences and relapses pointing towards ‘chronic cyanide toxicity’ remained enigmatic.

Specific changes the 2–3 DPG levels and Blood Gases were explained on the basis of N-carbamoylation of end-terminal valine residues of Hb. Soon, several other end-terminal -amino groups of tissue proteins were also found to be N-carbamoylated. Had the attempts at demonstrate S-carbamoylation of glutathione and other SH radicals of tissue enzymes like rhodanese succeeded, perhaps the underlying mechanism of chronic cyanide toxicity due to MIC might have been resolved.

Based on the practical lessons learnt in Bhopal, an attempt will be made to present the salient pathological and toxicological findings, followed by a brief outline of the principles of planned laboratory management for alleviation of human suffering from future chemical disasters.