低汞触媒中氯化汞含量的测定

介绍了灼烧法和容量法两种低汞触媒中氯化汞含量的测定方法,并分析了在测试过程中的细节要求。     

Selective Separation of Hg2+ on Modified Crosslinked Chitosan Beads Enriched with Amine Groups

Sodium tripolyphosphate crosslinked chitosan was prepared and immobilized with pentamine moieties. The samples obtained were characterized by elemental analysis and FT-IR. The adsorption behavior of the samples was studied towards Hg²⁺ using batch and column methods. The adsorption depended on the pH of the medium and was explained to proceed via complex formation and/or ion exchange mechanisms. The uptake capacity was found to be 4.7 mmol/g at pH = 2. Selective separation of Hg²⁺ from a solution containing Pb²⁺, Cu²⁺, Ca²⁺, Zn²⁺, Fe³⁺, and Mg²⁺ was achieved at pH = 1. The values of the kinetics and the thermodynamic parameters of the uptake process were reported. The flow rate of 3 mL/min in column experiments was found to be the most preferable rate. The regeneration of the loaded resin was performed using 0.5 M potassium iodide.     

Removal of Trace Concentrations of Heavy Metals Using Complexing Ion‐Exchange Resins

Abstract

Oak Ridge National Laboratory is examining potential new technologies for treating radiologically‐contaminated process wastewater. The current treatment facility is aging and is optimized to remove ⁹⁰Sr, but future wastewaters are likely to contain mostly activated metals, such as ⁵¹Cr and ⁶⁴Cu. Other low‐volume wastewaters may contain trace concentrations of Hg and U. Complexing ion‐exchange resins and other specialized sorbents were tested for removing trace concentrations of heavy metals. Short‐term column tests and batch loading tests were conducted using a surrogate wastewater and various sorbents. These tests showed that metal uptake was very rapid, and that good removal and relatively high loadings could be achieved from a very dilute wastewater surrogate. Forager M‐TU (Dynaphore, Inc.) showed the best overall results, removing 91.9% of the Cr, 99.3% of the Cu, >99.7% of the Hg, and >99.9% of the U with a contact time of 120 seconds in a short‐term column test.     

天然气及其伴生凝析油的脱汞技术

天然气作为一种清洁能源和霞要的化工基础原料,其应用在我国越来越广泛,除了每年120亿m^3的话气东输项目,我嘲还从澳犬利亚等圜家进口每年3000万t的LNG（液化天然气）以满足国内日益增长的消费需求。世界各地的气田采出的天然气都不同程度的含铂元索汞,汞的存在会严熏损坏天然气处理装置的低温铝制换热器,造成巨额的设备更换和停工损失,含汞的天然气产品也带来人员健康和环境问题。同时,天然气田伴生的凝析油由于其低廉的价格也被引进闲内,2006年闲内已经有乙烯厂家率先使用凝析油替代国内常见的石脑油作为裂解原料来火幅度降低原料成本,但凝析油也同样存在含汞的问题。因此,阔内外的天然气和伴生凝析油处理装置和研究机构在不断的追寻高效益低成本的脱汞科技,一系列先进的汞脱除技术已经被开发出来并在实际生产中得以应用。     

Reduced texaphyrin: A ratiometric optical sensor for heavy metals in aqueous solution

We report here a water-soluble metal cation sensor system based on the as-prepared or reduced form of an expanded porphyrin, texaphyrin. Upon metal complexation, a change in the redox state of the ligand occurs that is accompanied by a color change from red to green. Although long employed for synthesis in organic media, we have now found that this complexation-driven redox behavior may be used to achieve the naked eye detectable colorimetric sensing of several number of less-common metal ions in aqueous media. Exposure to In(III), Hg(II), Cd(II), Mn(II), Bi(III), Co(II), and Pb(II) cations leads to a colorimetric response within 10 min. This process is selective for Hg(II) under conditions of competitive analysis. Furthermore, among the subset of response-producing cations, In(III) proved unique in giving rise to a ratiometric change in the ligand-based fluorescence features, including an overall increase in intensity. The cation selectivity observed in aqueous media stands in contrast to what is seen in organic solvents, where a wide range of texaphyrin metal complexes may be prepared. The formation of metal cation complexes under the present aqueous conditions was confirmed by reversed phase high-performance liquid chromatography, ultra-violet-visible absorption and fluorescence spectroscopies, and high-resolution mass spectrometry.     

多壁碳纳米管负载FeS2的制备及脱汞性能分析

采用硝酸铁与硫脲在溶剂热反应条件下制备FeS₂,利用物理浸渍法将FeS₂负载至多壁碳纳米管（MWCNTs）上,借助扫描电镜（SEM）、X射线衍射（XRD）、X光电子能谱（XPS）等分析测试手段对制备样品的结构特性进行探究,通过固定床反应器研究模拟烟气氛围下吸附剂对烟气中单质汞的吸附特性。实验考察了不同FeS₂负载量、烟气初始汞浓度、床层温度以及O₂、NO和SO₂对吸附剂脱汞效率的影响。结果表明,制备出的FeS₂分散性较好,呈球状晶体,表面均匀覆盖着MWCNTs,成团簇状。当负载量为10%、反应温度为70℃时,FeS₂/MWCNTs的吸附效果最好,最高脱除效率能达到100%,60min后脱除效率仍有80.3%。TPD脱附曲线和XPS分析结果进一步表明烟气中的Hg⁰被氧化成Hg²⁺以HgS的形式附着在吸附剂表面,证实吸附剂以化学吸附为主。此外,汞脱除效率随初始汞浓度的增加而降低,汞吸附容量却随之增加,60min最高能达到5.1μg/g。酸性气体NO和SO₂的存在,占据了吸附剂表面的活性点位,不利于Hg⁰的吸附,但低浓度NO对吸附剂的整体效果影响不大,抗NO性能较好。     

UV/TiO_2光催化氧化工艺脱汞的试验研究

UV/TiO_2光催化技术在TiO_2催化剂的作用下可将烟气中Hg~0氧化脱除。利用自制的UV/TiO_2氧化试验台研究了影响Hg~0去除率的相关因素,结果表明,在无催化剂和有紫外灯情况下可脱除少量Hg~0;Hg~0去除率随催化剂活性组分含量的增加而上升,但上升速率逐渐下降;在温度(50～200)℃范围内,Hg~0去除率无明显变化;Hg~0去除率随着Hg~0初始浓度的升高逐渐下降;Hg~0去除率随着烟气中氧含量先上升后趋于不变。UV/TiO_2氧化工艺脱汞可为燃煤电厂烟气脱汞提供理论指导。     

我国电石法聚氯乙烯发展的挑战和趋势

回顾了我国聚氯乙烯工业“十一五”期间的发展情况,指出了其在“十二五”期间所面临的挑战。如汞污染的防治、节能减排及物流和人力成本,并预测了我国电石法聚氯乙烯的发展前景。     

利用超声波阳极溶出伏安法测定痕量汞

以阳极溶出伏安法研究了超声波作用下汞在金电极上的电化学行为,建立了痕量汞的超声波-阳极溶出伏安法。采用超声波增加了汞的溶出峰电流,提高了方法的灵敏度,在优化实验条件下,汞离子浓度在0～25μg/L范围内,线性方程为I=1.08c+0.27,(μg/L,R=0.998),加入标准汞溶液为6μg/L时,测量值的重复性和精确度都在5%以内。常见金属离子一般不干扰,方法简便快速。     

ICP法测定盐水中的微量汞

介绍一种精度高、重现性好的测定方法-ICP法测定盐水中的微量汞.