Formation of PCDD/Fs from oxidation of 2-monochlorophenol over an Fe2O3/silica surface

The role of iron in surface-mediated formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from 2-chlorophenol (2-MCP) was investigated over the temperature range of 200-550 °C under oxidative conditions. In order to compare and contrast with previous work on copper and ferric oxide-mediated pyrolysis of 2-MCP, identical reaction conditions were maintained (50 ppm 2-MCP, model fly-ash particles containing 5% Fe₂O₃ on silica). Observed products included dibenzo-p-dioxin (DD), 1-monochlorodibenzo-p-dioxin (1-MCDD), dibenzofuran (DF), 4,6-dichlorodibenzofuran (4,6-DCDF), 2,4- and 2,6-dichlorophenol, 2,4,6-trichlorophenol, quinone, catechol, chloro-o-quinone, chlorocatechol and polychlorinated benzenes. Yields of DD and 1-MCDD were 2 and 5 times higher than under pyolysis conditions, respectively. Although 4,6-DCDF was the major PCDD/F product formed with a yield that was 2.5× greater than under pyrolysis, the yield of non-chlorinated DF, which was the dominant PCDD/F product under pyrolysis, decreased by a factor of 3. Furthermore, the ∼2× higher yield of PCDDs under oxidative conditions resulted in a PCDD to PCDF ratio of 0.75 compared to a relatively low ratio of 0.39 previously observed under pyrolytic conditions.     

南方某市水源水、自来水的致突变活性现状与改善对策

用Ａｍｅｓ试验方法评价现有水处理工艺与模拟水厂水处理工艺对水的致突变活性的控制效果。结果表明,水源水的致突变活性呈阳性,Ｔ（传统处理）工艺出水致突变活性进一步增强;ＢＴ（Ｂ为生物处理）工艺能使致突变活性降低,但仍为阳性;ＢＴＣ（Ｃ为活性炭）、ＯＢＴＣ（Ｏ代表臭氧）组合工艺能有效去除和控制水中的致突物,使水的致突变活性转变为阴性反应。     

Accident modelling and analysis in process industries

Accident modelling is a methodology used to relate the causes and effects of events that lead to accidents. This modelling effectively seeks to answer two main questions: (i) Why does an accident occur, and (ii) How does it occur. This paper presents a review of accident models that have been developed for the chemical process industry with in-depth analyses of a class of models known as dynamic sequential accident models (DSAMs). DSAMs are sequential models with a systematic procedure to utilise precursor data to estimate the posterior risk profile quantitatively. DSAM also offers updates on the failure probabilities of accident barriers and the prediction of future end states. Following a close scrutiny of these methodologies, several limitations are noted and discussed, and based on these insights, future work is suggested to enhance and improve this category of models further.     

Investigation of suitable precursors for manganese oxide catalysts in ethyl acetate oxidation

The control of ethyl acetate emissions from fermentation and extraction processes in the pharmaceutical industry is of great importance to the environment. We have developed three Mn₂O₃ catalysts by using different Mn precursors (MnCl₂, Mn(CH₃COO)₂, MnSO₄), named as Mn₂O₃-Cl, -Ac, -SO₄. The tested catalytic activity results showed a sequence with Mn precursors as: Mn₂O₃-Cl > Mn₂O₃-Ac > Mn₂O₃-SO₄. The Mn₂O₃-Cl catalyst reached a complete ethyl acetate conversion at 212℃ (75℃ lower than that of Mn₂O₃-SO₄), and this high activity 100% could be maintained high at 212℃ for at least 100 hr. The characterization data about the physical properties of catalysts did not show an obvious correlation between the structure and morphology of Mn₂O₃ catalysts and catalytic performance, neither was the surface area the determining factor for catalytic activity in the ethyl acetate oxidation. Here we firstly found there is a close linear relationship between the catalytic activity and the amount of lattice oxygen species in the ethyl acetate oxidation, indicating that lattice oxygen species were essential for excellent catalytic activity. Through H₂ temperature-programmed reduction (H₂-TPR) results, we found that the lowest initial reduction temperature over the Mn₂O₃-Cl had stronger oxygen mobility, thus more oxygen species participated in the oxidation reaction, resulting in the highest catalytic performance. With convenient preparation, high efficiency, and stability, Mn₂O₃ prepared with MnCl₂ will be a promising catalyst for removing ethyl acetate in practical application.     

Disinfection by-product (DBP) research in China: Are we on the track?

Disinfection by-products (DBPs) formed during water disinfection has drawn significant public concern due to its toxicity. Since the first discovery of the trihalomethanes in 1974, continued effort has been devoted on DBPs worldwide to investigate the formation mechanism, levels, toxicity and control measures in drinking water. This review summarizes the main achievements on DBP research in China, which included: (1) the investigation of known DBP occurrence in drinking water of China; (2) the enhanced removal of DBP precursor by water treatment process; (3) the disinfection optimization to minimize DBP formation; and (4) the identification of unknown DBPs in drinking water. Although the research of DBPs in China cover the whole formation process of DBPs, there is still a challenge in effectively controlling the drinking water quality risk induced by DBPs, an integrated research framework including chemistry, toxicology, engineering, and epidemiology is especially crucial.     

Risk assessment of rare events

Rare events often result in large impacts and are hard to predict. Risk analysis of such events is a challenging task because there are few directly relevant data to form a basis for probabilistic risk assessment. Due to the scarcity of data, the probability estimation of a rare event often uses precursor data. Precursor-based methods have been widely used in probability estimation of rare events. However, few attempts have been made to estimate consequences of rare events using their precursors. This paper proposes a holistic precursor-based risk assessment framework for rare events. The Hierarchical Bayesian Approach (HBA) using hyper-priors to represent prior parameters is applied to probability estimation in the proposed framework. Accident precursor data are utilized from an information theory perspective to seek the most informative precursor upon which the consequence of a rare event is estimated. Combining the estimated probability and consequence gives a reasonable assessment of risk. The assessed risk is updated as new information becomes available to produce a dynamic risk profile. The applicability of the methodology is tested through a case study of an offshore blowout accident. The proposed framework provides a rational way to develop the dynamic risk profile of a rare event for its prevention and control.     

1995年山东苍山5.2级地震构造背景及前兆地震活动特征

简述了苍山ＭＳ５．２地震的基本概况,分析了苍山５２级地震构造背景,据这次地震的余震空间分布、等震线长轴、震源机制解、地震活动条带和地质资料分析认为北西向的苍山 新泰断裂和北东向的荣成 临沂断裂可能是苍山５２级地震的地震断层。在１９８５年６月以前,鲁南地区的地震活动呈随机分布,１９８５年６月以后ＭＬ≥３．０地震主要集中在新泰 苍山 莒县之间的三角地带,来回迁移;１９７４年以后沿苍山 尼山断裂的ＭＬ≥３．０地震都发生在５２级地震震中附近,说明在苍山 尼山断裂与沂沭断裂带交汇区西侧较长时间的能量积蓄。苍山５２级地震前最后发生的两个ＭＬ≥２．０地震与苍山５２级地震震中形成沿地震断层的临震小震活动条带。     

Accurate prediction of air quality response to emissions for effective control policy design

Designing effective control policy requires accurate quantification of the relationship between the ambient concentrations of O₃and PM_2.5and the emissions of their precursors.However,the challenge is that precursor reduction does not necessarily lead to decreases in the concentrations of O₃and PM_2.5,which are formed by multiple precursors under complex physical and chemical processes;this calls for the development of advanced model technologies to prov...     

收缴易制毒化学品环境无害化销毁主要问题及对策

随着我国合成毒品的泛滥和易制毒化学品收缴量的激增,收缴易制毒化学品的环境无害化销毁成为环境保护工作需要关注的一个新领域。文章概述了当前我国收缴易制毒化学品的基本特性及其销毁现状,分析了销毁过程的环境风险及目前存在的主要问题,提出了相应的解决对策,以期为推进我国收缴易制毒化学品环境无害化销毁工作提供参考。     

Formation and control of disinfection byproducts and toxicity during reclaimed water chlorination: A review

Chlorination is essential to the safety of reclaimed water; however, this process leads to concern regarding the formation of disinfection byproducts (DBPs) and toxicity. This study reviewed the formation and control strategies for DBPs and toxicity in reclaimed water during chlorination. Both regulated and emerging DBPs have been frequently detected in reclaimed water during chlorination at a higher level than those in drinking water, indicating they pose a greater risk to humans. Luminescent bacteria and Daphnia magna acute toxicity, anti-estrogenic activity and cytotoxicity generally increased after chlorination because of the formation of DBPs. Genotoxicity by umu-test and estrogenic activity were decreased after chlorination because of destruction of toxic chemicals. During chlorination, water quality significantly impacted changes in toxicity. Ammonium tended to attenuate toxicity changes by reacting with chlorine to form chloramine, while bromide tended to aggravate toxicity changes by forming hypobromous acid. During pretreatment by ozonation and coagulation, disinfection byproduct formation potential (DBPFP) and toxicity formation potential (TFP) occasionally increase, which is accompanied by DOC removal; thus, the decrease of DOC was limited to indicate the decrease of DBPFP and TFP. It is more important to eliminate the key fraction of precursors such as hydrophobic acid and hydrophilic neutrals. During chlorination, toxicities can increase with the increasing chlorine dose and contact time. To control the excessive toxicity formation, a relatively low chlorine dose and short contact time were required. Quenching chlorine residual with reductive reagents also effectively abated the formation of toxic compounds.