土壤组分对四氯乙烯吸附解吸行为的影响

吸附和解吸作用是影响四氯乙烯(PCE)在土壤环境中迁移、归趋的主要过程.采用总有机碳(TOC)含量为2.23%的原土及经H2O2、375℃、600℃处理后所得的3种土样为吸附剂,通过批量平衡实验,考察了TOC含量、软碳、硬碳、初始液相PCE浓度c0等因素对PCE吸附解吸行为的影响.结果表明,当反应温度为16℃且c0为5~80 mg·L-1时,Freundlich方程能较好地拟合PCE在土样中的吸附及解吸等温线(r2>0.96);原土对PCE的吸附以土壤有机物(SOM)的贡献率(>60%)为主,且硬碳是其主要影响因素;原土中SOM与矿物质对PCE的解吸贡献率相当,但在SOM对PCE解吸的贡献率中,软碳占80%以上;硬碳对PCE的吸附贡献率以及软碳和矿物质的解吸贡献率随c0的增加而升高.PCE在4种土样中都表现出一定的吸附解吸异质性,且硬碳是导致原土异质性的主要原因.     

Investigations on explosion characteristics of ethyl acetate

In this study, the confined explosion characteristics of ethyl acetate were investigated in a constant volume explosion vessel using the initial pressure of 1–4 bar, the initial temperature of 358–418 K, and the equivalence ratio of 0.8–1.4. It was revealed that the peak explosion pressure and the maximum pressure rise rate of ethyl acetate increased as the initial pressure increased and the initial temperature decreased. The peak explosion pressure and maximum pressure rise rate were obtained at the equivalence ratio of 1.2 due to increased heat release rate. Furthermore, the explosion time decreased as the initial pressure decreased. In summation, EA experimental and theoretical deflagration index were investigated and compared. The experimental deflagration index showed that EA explosion was less dangerous, whereas the theoretical deflagration predicted that the explosion could be more hazardous.     

Devising indicators of sustainable development for the mining and minerals industry: An analysis of critical background issues

The exact application of sustainable development in the mining and minerals industry has precipitated considerable debate in recent years. Since the publication of the Brundtland Commission's Report, Our Common Future, numerous explanations have been put forth in an attempt to define sustainable development in the mining and minerals context. Specifically, the inability of the Brundtland Report to outline an effective sustainability framework, combined with its contention that no single blueprint for sustainable development exists, has prompted a number of academics and practitioners to provide personal viewpoints on the application of sustainable development in the mining and minerals industry. This paper focuses on one aspect of the mining and minerals-sustainable development debate: the corporate perspective. It first uses the burgeoning body of literature to define sustainable development in the corporate mining context. Second, it addresses, against the background of this interpretation, many of the salient issues associated with developing a series of plausible Sustainable Development Indicators (SDIs) for use in the mining and minerals extraction industry. The paper clearly illustrates the difficulty in both arriving at a suitable working definition of sustainable development for an industry, and developing an acceptable set of universal standards for measuring environmental and socioeconomic performance.     

酸改性粘土矿物处理含磷废水的研究

文章用盐酸对膨润土、高岭土、凹凸棒土及沸石进行了改性研究,对含磷废水的吸附处理结果表明,改性后的实验样品对磷的净化能力明显增强,去除率分别增加膨润土27.45%、沸石19.11%、高岭土39.7%、凹凸棒土11.3%,最大去除率可达到膨润土45.59%、沸石32.84%、高岭土77.45%、凹凸棒土30.9%。膨润土、沸石、高岭土的改性随着酸用量的增加对磷的吸附效果随之增加,凹凸棒土最佳酸用量为3%(体积分数)。处理模拟的废水的结果表明,在改性后的高岭土投加量为0.5 g/25 mL废水时,对磷的去除率达到95.9%,吸附后水中的磷浓度为0.49 mg/L,处理后水中的磷浓度达到废水排放一级标准的要求。四种粘土样品改性前后对磷的吸附特征可以用Langmuir方程和Freundlich方程描述。     

Unraveling the size distributions of surface properties for purple soil and yellow soil

Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges(i.e. 10, 1–10, 0.5–1, 0.2–0.5 and 0.2 μm) for a purple soil(Entisol) and a yellow soil(Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction.We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles( 1 μm), and almost half of the specific surface area and surface charge came from the smallest particles( 0.2 μm). Vermiculite,illite, montmorillonite and mica dominated in the colloidal-sized particles, of which the smallest particles had the highest proportion of vermiculite and montmorillonite. For a given size fraction, the purple soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy.Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the 0.2 μm nanoparticles made the largest contribution to soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties.     

灰分对高硫煤热解部分气化硫变迁的影响

采用分步脱除矿物质方法,对义马原煤及HCl,HCl-HF,HCl-HNO₃处理后煤样,分别在固定床反应器中考察了热解部分气化下硫的脱除规律.结果表明:一方面在热解过程中原煤及酸处理煤样H₂S和COS的析出均呈双峰趋势,其析出值主要受温度、原煤中灰分和HNO₃氧化作用;另一方面,在部分气化和酸处理后煤样热解半焦在600℃～900℃范围内硫脱除率可达50%～80%,800℃时,无机硫可完全脱除.而原煤热解半焦总硫,无机硫的脱除率在700℃时最大.气化温度的升高,加强了碱性矿物质的固硫作用,其结果是900℃气化时,总硫和无机硫脱除率降低.酸处理后有机硫含量基本保持不变,其噻吩结构只随碳骨架的气化而析出.     

甲磺隆除草剂的测定方法及其吸附行为研究

采用批量平衡法系统研究了甲磺隆除草剂在几种土壤（熟化红壤、砖红壤性红壤、红筋泥、砖红壤）和矿物（高岭石、针铁矿、和Ca²⁺、Al³⁺、Cu²⁺单离子饱和蒙脱石）上的吸附行为.建立了硼酸-硼砂缓冲液体系的毛细管电泳测定甲磺隆的分析方法.甲磺隆在本实验条件下能够与土壤中的杂质达到基线分离,迁移时间为4.6 min.对比实验表明,毛细管电泳法测定甲磺隆与高效液相色谱法具有一致性.然而,毛细管电泳法能显著节省测试时间和成本,在本类吸附实验研究中具有很好的应用价值.吸附实验数据分析表明甲磺隆的吸附行为都可以用Freundlich模型描述,矿物和土壤的K_f值分别在0.82～199.69和1.97～10.48范围.在几种影响甲磺隆吸附的因素中,pH的影响作用最为显著,说明静电作用可能是甲磺隆在土壤及矿物上吸附的主要机理.     

Products and stability of phosphate reactions with lead under freeze-thaw cycling in simple systems

Orthophosphate fixation of metal contaminated soils in environments that undergo freeze-thaw cycles is understudied. Freeze-thaw cycling potentially influences the reaction rate, mineral chemical stability and physical breakdown of particles during fixation. This study determines what products form when phosphate (triple superphosphate [Ca(H₂PO₄)₂] or sodium phosphate [Na₃PO₄]) reacts with lead (PbSO₄ or PbCl₂) in simple chemical systems in vitro, and assesses potential changes in formation during freeze-thaw cycles. Systems were subjected to multiple freeze-thaw cycles from +10 °C to −20 °C and then analysed by X-ray diffractometry. Pyromorphite formed in all systems and was stable over multiple freeze-thaw cycles. Low temperature lead orthophosphate reaction efficiency varied according to both phosphate and lead source; the most time-efficient pyromorphite formation was observed when PbSO₄ and Na₃PO₄ were present together. These findings have implications for the manner in which metal contaminated materials in freezing ground can be treated with phosphate.     

Potential for microbially mediated redox transformations and mobilization of arsenic in uncontaminated soils

Surface soil samples, which had no significant As contamination, were examined for As(V) reduction, As(III) oxidation and As mobilization capability. All five soil samples tested exhibited microbial As(V)-reducing activities both in aerobic and anaerobic conditions. Under aerobic conditions when As(V) reduction had almost ceased, oxidation of As(III) to As(V) occurred, whereas only As(V) reduction was observed under anaerobic conditions. In cultures incubated with As(III), As(III) was oxidized by indigenous soil microbes only under aerobic conditions. These results indicate that microbial redox transformations of As are ubiquitous in the natural environment regardless of background As levels. Mobilization through microbially mediated As(V) and Fe(III) reduction occurred both in the presence and absence of oxygen. Significant variation in dissolved As occurred depending on the Fe contents of soils, and re-immobilization of As arose in the presence of oxygen, presumably as a consequence of dissolved As(III) and Fe(II) oxidation. There was no apparent correlation between dissolved Fe(II) and As, suggesting that reductive dissolution of Fe(III) minerals does not necessarily determine the extent of As release from soils.     

PAC与粘土矿物混凝去除颤藻及残余铝形态研究

研究了PAC与不同粒径的天然粘土矿物复合混凝去除给水中的颤藻。结果表明,两者复合除藻效果显著优于单加PAC。当PAC浓度为12 mg/L,矿物浓度为24 mg/L,粒径为160目时,除藻效果最好,浊度和叶绿素a去除率分别为98.2%和100%。两者复合后PAC形态含量都发生了变化,悬浮态铝含量相对增加,溶解态铝含量相对减少,总残余铝量减小。