交叉上市公司社会责任缺陷披露的市场反应——基于紫金矿业突发渗漏环保事故的案例研究

伴随着工业化进程加快,社会责任缺失现象日益严重,各类企业违法违规事故层出不穷,其中不乏国有大型控股公司,这种现象引起了投资者、监管机构等利益相关者的广泛关注。在此背景下,研究资本市场对上市公司社会责任缺陷披露的反应具有重要的理论意义和现实意义。本文以交叉上市的紫金矿业为例,采用事项研究法,检验了A股和H股市场对紫金矿业集团股份有限公司发布的一系列有关紫金山铜矿湿法厂污水池突发渗漏环保事故重要公告的市场反应,并比较了两地市场对同一公告的反应差异。研究发现:两地市场对重大事故公告均提前预知并呈负面反应,在公告前A股市场反应程度大于H股市场,公告发布后H股市场投资者更加敏感;两地市场对董事会(临时)决议公告呈正面反应,但H股市场投资者更加谨慎;对处罚公告两市反应不同,A股市场未对处罚公告作出反应,H股市场对处罚公告呈负面反应;总体而言,H股市场与A股市场反应程度存在显著差异。     

Dechlorination of PCBs in the simulative transformer oil by microwave-hydrothermal reaction with zero-valent iron involved

The conventional hydrothermal reaction with iron powder, NaOH and H₂O as reactants was reported to occur at temperature above 423 K, and iron oxides (Fe₃O₄ and NaFeO₂) and hydrogen were produced. In this study, microwave heating was adopted to take the place of conventional heating to induce the hydrothermal reaction. Under microwave irradiation, NaOH and H₂O absorbed microwave energy by space charge polarization and dipolar polarization and instantly converted it into thermal energy, which initiated the hydrothermal reaction that involved with zero-valent iron. X-ray diffraction (XRD) analysis found Fe₃O₄/NaFeO₂ and confirmed the occurrence of microwave-induced hydrothermal reaction. The developed microwave-hydrothermal reaction was employed for the dechlorination of PCBs. Hexadecane containing 100 mg L⁻¹ of Aroclor1254 was used as simulative transformer oil, and the dechlorination of PCBs was evaluated by GC/ECD, GC/MS and ion chromatography. For PCBs in 10 mL simulative transformer oil, almost complete dechlorination was achieved by 750 W microwave irradiation for 10 min, with 0.3 g iron powder, 0.3 g NaOH and 0.6 mL H₂O added. The effects of important factors including microwave power and the amounts of reactants added, on the dechlorination degree were investigated, moreover, the dechlorination mechanism was suggested. Microwave irradiation combined with the common and cheap materials, iron powder, NaOH and H₂O, might provide a fast and cost-effective method for the treatment of PCBs-containing wastes.     

Bromination of selected pharmaceuticals in water matrices

The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, phenacetin, and hydrochlorothiazide) was studied with these compounds individually dissolved in ultra-pure water. The apparent rate constants for the bromination reaction were determined as a function of the pH, obtaining the sequence amoxicillin > naproxen ? hydrochlorothiazide ≈ phenacetin ≈ metoprolol. A kinetic mechanism specifying the dissociation reactions and the species formed for each compound according to its pK_a value and the pH allowed the intrinsic rate constants to be determined for each elementary reaction. There was fairly good agreement between the experimental and calculated values of the apparent rate constants, confirming the goodness of the proposed reaction mechanism.In a second stage, the bromination of the selected pharmaceuticals simultaneously dissolved in three water matrices (a groundwater, a surface water from a public reservoir, and a secondary effluent from a WWTP) was investigated. The pharmaceutical elimination trend agreed with the previously determined rate constants. The influence of the main operating conditions (pH, initial bromine dose, and characteristics of the water matrix) on the degradation of the pharmaceuticals was established. An elimination concentration profile for each pharmaceutical in the water matrices was proposed based on the use of the previously evaluated apparent rate constants, and the theoretical results agreed satisfactorily with experiment. Finally, chlorination experiments performed in the presence of bromide showed that low bromide concentrations slightly accelerate the oxidation of the selected pharmaceuticals during chlorine disinfection.     

O3氧化结合化学吸收同时脱硫脱硝的动力学及热力学研究

构建了O3氧化多种污染物的反应机制,并对O3氧化SOx、NOx过程进行动力学模拟,然后利用热力学原理计算出Ca(OH)2和CaCO3湿法烟气同时脱硫脱硝吸收反应达到平衡时SOx和NOx的分压力.结果表明,Ca(OH)2作吸收剂湿法烟气同时脱硫脱硝比CaCO3作吸收剂效果好,而且两者几乎100％地去除烟气中的SOx和NO...     

赤泥协同Fenton法处理焦化废水的研究

采用赤泥吸附协同Fenton法处理焦化废水,两者协同处理对COD的去除率高于其单独处理之和.考察了赤泥投加量、初始pH值、反应温度、H2O2浓度和Fe2+浓度等因素对降解效果的影响,实验结果表明,在20 g/L的赤泥、初始pH=3、80 mmol/L的H2O2、224 mg/L的Fe2+的最佳条件下,经过120 min...     

超声波-铁粉协同降解五氯酚

通过超声波-铁粉联合体系协同降解废水中的五氯酚(PCP).实验结果表明:降解120 min后,PCP去除率可达90.4％;在该体系中铁粉被逐渐腐蚀成Fe2+,随降解时间的延长,Fe2+浓度逐渐增加;体系中的Fe2+可以促进·OH的产生,并且可以与超声空化作用下产生的H2O2发生Fenton试剂氧化反应降解PCP;超声波...     

锐钛矿-金红石混合晶型TiO2降解气相苯

用溶胶-凝胶法并通过控制煅烧温度合成不同晶相比的混合晶型纳米TiO_2,在紫外光光照下降解气相苯。考察了苯初始质量浓度、紫外灯光照强度和催化剂加入量对苯去除率的影响;探究了光催化降解气相苯的动力学特征。结果表明:450℃煅烧制备的催化剂降解苯效率最高,此催化剂金红石相质量分数为6.30%;在苯初始质量浓度为74.39 mg/m~3、催化剂加入量为7 g、光照强度为2.18 klux的最佳条件下反应84 min,苯去除率达99.73%;光催化降解率与光照强度之间符合0.5级动力学特征;当催化剂加入量为3 g时,单位时间单位质量催化剂降解苯的质量最多;苯的光催化降解反应均符合一级动力学方程。     

Fenton试剂处理汽车油漆废渣

采用Fenton试剂处理汽车油漆废渣。考察了FeSO_4用量、H_2O_2用量、反应温度、反应时间对处理效果的影响。实验结果表明,在FeSO_4用量为20.5 mg/g、H_2O_2用量为0.6 g/g、反应温度为80 ℃、反应时间为3 h的最优条件下,清漆渣、色漆渣、底漆渣3种漆渣的干基减量率均为20%左右,湿基减量率分别为67.9%、48.2%和64.2%,3种产物的脱水性能均有不同程度的提高,处理后废液的COD均为2 000 mg/L左右。采用Fenton试剂处理后的清漆渣产物粒径与原料相似,产物颗粒球形度高,表面粗糙,内部为多孔结构,产物作为固体燃料时燃烧更充分。Fenton试剂处理未对漆渣中的树脂主体产生较大的破坏。     

不同类型填料的三维电极/Fenton试剂法处理苯酚废水

采用不同类型填料对三维电极/Fenton试剂法处理苯酚模拟废水进行研究.结果表明.不同类型活性炭填料对苯酚去除率有很大影响,粒炭不适合做粒子电极,采用5.0 mm柱炭处理效果较好;采用石英砂与活性炭混合填料的处理效果比单一活性炭填料好,但苯酚去除率提高不明显;电解槽反应器中按比例投加涂膜活性炭和活性炭混合填料能明显提高苯酚去除率;当涂膜活性炭与活性炭体积比为1,2时,苯酚去除率最高,达96.8%.     

The effect of alkyl chain length on the degradation of alkylimidazolium- and pyridinium-type ionic liquids in a Fenton-like system

Background, aim, and scope  Ionic liquids are regarded as essentially “green” chemicals because of their insignificant vapor pressure and, hence, are a good alternative to the emissions of toxic conventional volatile solvents. Not only because of their attractive industrial applications, but also due to their very high stability, ionic liquids could soon become persistent contaminants of technological wastewaters and, moreover, break through into natural waters following classical treatment systems. The removal of harmful organic pollutants has forced the development of new methodologies known as advanced oxidation processes (AOPs). Among them, the Fenton and Fenton-like reactions are usually modified by the use of a higher hydrogen peroxide concentration and through different catalysts. The aim of this study was to assess the effect of hydrogen peroxide concentration on degradation rates in a Fenton-like system of alkylimidazolium ionic liquids with alkyl chains of varying length and 3-methyl-N-butylpyridinium chloride. Materials and methods  The ionic liquids were oxidized in dilute aqueous solution in the presence of two different concentrations of hydrogen peroxide. All reactions were performed in the dark to prevent photoreduction of Fe(III). The concentrations of ionic liquids during the process were monitored with high-performance liquid chromatography. Preliminary degradation pathways were studied with the aid of ¹H NMR. Results  Degradation of ionic liquids in this system was quite effective. Increasing the H₂O₂ concentration from 100 to 400 mM improved ionic liquid degradation from 57–84% to 87–100% after 60 min reaction time. Resistance to degradation was weaker, the shorter the alkyl chain. Discussion  The compound omimCl was more resistant to oxidation then other compounds, which suggests that the oxidation rates of imidazolium ionic liquids by OH· are structure-dependent and are correlated with the n-alkyl chain length substituted at the N-1-position. The level of degradation was dependent on the type of head group. Replacing the imidazolium head group with pyridinium increased resistance to degradation. Nonetheless, lengthening the alkyl chain from four to eight carbons lowered the rate of ionic liquid degradation to a greater extent than changing the head group from imidazolium to pyridinium. 1H-NMR spectra show, in the first stage of degradation, that it is likely that radical attack is nonspecific, with any one of the carbon atoms in the ring and the n-alkyl chain being susceptible to attack. Conclusions  The proposed method has proven to be an efficient and reliable method for the degradation of imidazolium ionic liquids by a Fenton-like reagent deteriorated with lengthening n-alkyl substituents and by replacing the imidazolium head group with pyridinium. The enhanced resistance of 1-butyl-3-methylpyridinium chloride when the resistance of imidazolium ionic liquids decreases with increasing H₂O₂ concentration is probably indicative of a change in the degradation mechanism in a vigorous Fenton-like system. H-NMR spectra showed, in the first stage of degradation, that radical attack is nonspecific, with any one of the carbon atoms in the ring and the n-alkyl chain being susceptible to attack. Recommendations and perspectives  Since ionic liquids are now one of the most promising alternative chemicals of the future, the degradation and waste management studies should be integrated into a general development research of these chemicals. In the case of imidazolium and pyridinium ionic liquids that are known to be resistant to bio- or thermal degradation, studies in the field of AOPs should assist the future structural design as well as tailor the technological process of these chemicals