煤中碘的淋滤行为研究

用不同pH值溶液对煤进行动态淋滤实验,用电感耦合等离子体质谱(ICP-MS)测定不同pH值淋滤液在不同时间段获取的淋出液中碘的浓度,以及煤和淋滤后残留煤的高温热水解溶液中碘的含量。结果表明,淋滤液pH值、淋滤时间、煤中碘的赋存形态及在煤中的赋存部位对碘的淋出有重要影响。淋滤液的酸性越强,煤中碘的淋出越多,pH值为2.0和pH值为4.0溶液对煤中碘的淋出率(η)分别为7.22%和6.20%;但pH值为2.0溶液的淋出液中碘的量小于pH值为4.0溶液的淋出液中碘的量,其百分率(w_x)分别为1.920 0%和5.420 0%。pH 2.0淋滤液,在前30 h内淋出液中碘的平均浓度为10.9 μg/L;而pH值为4.0淋滤液,在前110 h内淋出液中碘的平均浓度为10.6 μg/L;pH值为6.0和pH值为7.5溶液能淋出煤中碘很少。在酸性溶液作用下,首先被淋出的碘是存在煤颗粒表面少量的水溶态和离子交换态碘及大部分碳酸盐态和铁锰氧化物结合态碘,然后煤基质内部的部分水溶态和离子交换态碘及少量的碳酸盐结合态及铁锰氧化物结合态碘等才被淋出。     

燃煤电厂异相凝并飞灰重金属淋滤特性

采集了燃煤电厂的异相凝并后飞灰，分析了其物理化学特性。并通过淋滤实验研究了飞灰中重金属As、Se、Pb的环境稳定性。结果表明，凝并飞灰的粒径峰值为138.04 μm，而粉煤灰为60.26 μm；凝并后细颗粒凝聚成了较大的颗粒；凝并飞灰中重金属As、Se、Pb含量均高于同工况下粉煤灰中的含量，且后序脱硫环节所产生石膏中重金属的含量有所下降；批淋滤实验研究结果表明，凝并飞灰中的重金属浸出能力受淋滤液的pH值影响较大，温和环境和碱性条件抑制了As的浸出，酸性和碱性条件抑制了Se的浸出，而碱性条件抑制了Pb的浸出。柱淋滤实验研究结果表明，在酸性溶液和水溶液中，凝并飞灰的重金属浸出能力均受到了抑制。     

石嘴山电厂煤中微量元素的迁移释放行为

应用电感耦合等离子体质谱（ICP-MS）和原子荧光光谱（AFS）对中国西北部石嘴山电厂的原煤、底灰和飞灰中Hg、As、Se、Pb、Cr、Cd、Mo、Ni、Co、U和Th 11种微量元素的含量进行了测定。根据底灰和飞灰的产率, 结合微量元素在底灰和飞灰中的含量计算了电厂燃煤过程中微量元素的挥发性。结果表明, Hg、Cd、Se、As四种元素在燃煤过程的挥发率均在50%以上, 最高可达70%。通过对底灰和飞灰在酸性介质下的柱淋滤实验研究了底灰和飞灰中微量元素在60h内的迁移释放行为。Mn、Ni、Co、As四种元素的最大淋出率均超过2.0%, 最高接近10.0%, 并且还未达到淋滤平衡。根据微量元素的挥发和淋滤释放特性建立了电厂煤中有害微量元素在燃烧和淋滤过程中的释放分配模型。结果显示, 燃煤过程中的挥发是微量元素释放的主要形式, 部分元素的淋滤释放也可对周围水环境造成污染。
     

氧化钙对流化床燃煤飞灰中砷的淋滤特性影响

在实验室小型流化床实验装置上,利用添加氧化钙研究了原煤中钙硫比变化对燃煤过程中砷在飞灰中的富集规律和飞灰中砷的浸出特性的影响。实验结果表明,增加钙硫比能有效促进砷在飞灰中富集,降低砷的排放。砷与氧化钙的反应受制于钙的硫化反应控制。飞灰中砷的浸出与滤液pH值关系显著,碱性飞灰导致滤液pH值增大,能有效抑制飞灰中砷的浸出。碱性飞灰中砷的浸出历程为飞灰中砷在短时间内快速溶出;随着滤液pH值增大,溶出的砷与钙发生二次反应形成钙砷化合物沉淀,降低滤液中砷浓度。     

铜质水表中重金属溶出的研究

利用ICP-MS光谱仪,探讨铜质水表中重金属的溶出,分析了水质、浸泡时间、pH值对重金属溶出的影响。各元素在模拟自来水中的溶出量是超纯水的1．5-2倍,溶出量由大到小依次为Cu,Pb,Cr（VI）,Cd;一般在0．5d时出现溶出拐点,在4d时达基本饱和;在pH4的酸性水质中,各元素的溶出量为极大值。该方法适于铜质水表中重金属溶出的分析。     

铅硼聚乙烯屏蔽材料中总硼的测定

试样用稀硝酸溶解以除去大部分铅,经过滤后不溶物用碳酸钠加硝酸钠进行融熔。熔块用稀硝酸浸取,分取部分此母液,在pH 3.0的条件下通过离子交换柱分离除去残留在溶液中的铅,以pH 3.0的硝酸溶液淋洗分离柱,在淋出液中用常规的碱滴定法测定其总硼量。测定结果与蒸馏法的结果一致,方法的回收率为94%~106%,相对标准偏差(RSD)值为0.77%。     

离子型稀土矿柱浸过程氨氮平衡及尾矿氨氮形态转化研究

离子型稀土矿柱浸过程氨氮的平衡与迁移转化研究可以对浸矿剂硫酸铵用量的模拟运算提供理论参考。试验以定南某离子型矿土为对象,采用室内柱浸模拟的方式对离子型稀土原矿氨氮的分布、硫酸铵浸矿过程氨氮平衡及尾矿氨氮赋存转化的影响进行了试验。结果发现,离子型稀土原岩风化过程中,还可能伴随着离子相铵盐的生成,在浸矿过程中会伴随稀土一起被浸出,离子相铵盐含量随离子相稀土含量的升高而增加。硫酸铵柱浸过程中残留在尾矿内的氨氮量与浸出液中的氨氮量占比分别为50.76%和49.24%,浸矿剂中半数铵根主要起到保持浸矿过程中铵根浓度的作用,在浸矿后会随浸出液流出。离子型稀土尾矿水溶态和可交换态氨氮在矿土含水率的影响下会发生可逆转化,在尾矿矿土自然风干过程中,尾矿内水溶态氨氮含量占比由63.24%降至32.01%,离子型稀土尾矿水溶态与可交换态氨氮的赋存含量需要前置时间和矿土含水率等条件才能准确定义。     

中水消毒中溴代副产物在总消毒副产物中的比例及其影响因素

中水氯消毒过程中,溴代副产物(Br-DBPs)在总消毒副产物(DBPs)中的比例受到有效氯投加量、氯化时间、pH、氨氮(NH3-N)以及预臭氧化的影响.结果表明,溴代三卤甲烷(THMs)较溴代卤乙酸(HAAs)更易生成.溴对DBPs的贡献随有效氯投加量增加而降低.在氯化时间低于5h时,溴对THMs的取代能力呈增加趋势而对HAAs的取代能力急剧降低,5h后延长氯化时间又会降低溴代THMs的生成比例.而且,溴代DBPs的比例在酸性和碱性条件下相对较低.NH3-N浓度增加导致DBPs总量减少但同时提高了溴对DBPs的贡献.另外进行短时间的预臭氧化会促进溴的取代能力;延长臭氧化时间则会降低溴代DBPs的生成比例.     

反相离子对高效液相色谱-电感耦合等离子体质谱法测定富硒酵母中硒

富硒酵母样品用pH 7.5的Tris-盐酸缓冲溶液经超声破碎提取30min,于提取液中加链霉蛋白酶E在37℃搅拌18h,高速离心分离。取上清液经Millipore Corp超滤膜过滤,滤液中无机硒(Ⅵ及Ⅳ)和有机硒,即硒代半胱氨酸、硒代尿素和硒代蛋氨酸通过Waters Symmetry ShieldRP18色谱柱分离。用不同比例混合的甲醇-七氟丁酸溶液作流动相进行梯度洗脱,用电感耦合等离子体质谱法在线测定洗脱液中各种形态硒的含量。5种形态硒的质量浓度均在100μg·L-1以内呈线性。应用此法分析了富硒酵母样品,结果表明:无机硒占总硒量的1.63%,65%的硒以易被人体吸收的硒代蛋氨酸形式存在。     

萃取反萃取法研究新峪焦精煤中有机硫的赋存规律

以高含有机硫的新裕焦精煤为研究对象,采用萃取反萃取和分级萃取的分离方法及XPS、GC/MS等分析技术,对原煤和各族组分内不同结构的有机硫分布情况进行了研究,重点考察了各类型有机硫在煤有机质本体结构及族组分中的赋存规律。结果表明,组分总硫基赋存分率则与复杂性程度正好相反;可溶性含硫组分在总溶出物中的分布,相对不同族组分而言总体均衡;可溶性的共轭结构类有机硫主要赋存于煤密中质组中,其次是疏中质组中且以噻吩类为主,较少赋存于煤重质组中;而可溶性的脂肪结构类有机硫则主要赋存于煤重质组和密中质组中,较少赋存于疏中质组中;各族组分内有机硫的萃取率随时间的变化规律具有明显的加和性,族组分内可溶含硫组分的溶出行为相互独立,符合煤嵌布结构模型的基本思想;煤中不同形态有机硫的赋存遵循"相似相溶"原理。     

Structural and Electrosurface Properties of Porous Glasses of Various Composition in 1 : 1 Electrolyte Solutions

Complex studies of structural (the specific surface area, the volume porosity, the structural resistance coefficient, and the average pore radius), adsorption and electrokinetic (the electrical conductivity, the ion transport numbers, and the electrokinetic potential) characteristics as functions of pH and the concentration of KCl solution were carried out on porous glasses (PGs) with or without lead oxide and leached under various conditions. It was established that temperature of the leaching solution affects the colloidochemical parameters of PGs, while the addition of salt to the leaching solution exerts practically no influence on the PG behavior. It was shown that the addition of lead oxide results in the formation of membranes with thinner pores and higher surface charge.     

Contribution of acidic amino residues to the adsorption of peptides onto a stainless steel surface

The role of the acidic amino acid residues in the adsorption of peptides/proteins onto stainless steel particles was investigated using a peptide fragment from bovine beta-lactoglobulin, Thr-Pro-Glu-Val-Asp-Asp-Glu-Ala-Leu-Glu-Lys (T5 peptide), which has a high affinity to a stainless steel surface at acidic pHs, and its mutant peptides substituted with different numbers of acidic amino acid residues. The adsorption behavior of the mutant peptides as well as the T5 peptide were studied at pH 3 with respect to concentration and ionic strength dependencies and the reversibility of the adsorption process. The behavior of the peptides was generally characterized as two distinct irreversible adsorption modes, Mode I and Mode II. In Mode I, the amounts adsorbed lay on the ordinate at zero equilibrium concentration in the solution, while in Mode II, the amount adsorbed increased with increased equilibrium concentration. The area occupied by the peptides was predicted by molecular mechanics and molecular dynamics. The state of the peptides, when adsorbed, was investigated using FT-IR analysis. The FT-IR analyses revealed that the side carboxylic groups of the peptides adsorbed on the stainless steel surface were ionized, while they were unionized in the solution at pH 3. Thus, the interactions between the carboxylic groups of the peptide and the stainless steel surface can be considered to be largely electrostatic. The peptide having four acidic amino acid residues took a maximum adsorbed amount, the reason for which is discussed.     

Loss of water during heat treatment of acid leached glass and fused silica capillary columns

A study was carried out on the effects of acid leaching of capillary column wall materials. Leaching experiments with glass and fused silica were performed under static and dynamic conditions; moreover, the influence of the temperature was investigated. The amount of water released during different temperature programs was measured with a microwave plasma detector. Different leaching conditions and column wall materials cause considerable variations in water production. These results probably explain the disappointing deactivation efficiency obtained for fused silica and dynamically leached soft glass if HMDS is used. Evidence was found for an increase in surface area due to acid leaching.     

城市生活垃圾焚烧飞灰重金属的浸出特性

对用流化床焚烧炉混烧垃圾和煤的布袋飞灰进行了重金属的TCLP(Toxicity Characteristic Leaching Procedure)浸出特性实验，探讨了液固比、初始pH值及浸出时间对飞灰中重金属Pb、Cr、Cd、Ni、Cu、Zn的浸出影响。结果表明，重金属的浸出量都随着液固比的增加而增加，其中Cr、Cu一般呈上升趋势，Cd、Ni、Zn在液固比大于20时曲线变化较平缓，Pb的浸出规律比较特殊，有一个明显的波峰和波谷。重金属在浸取液的pH≤2.90时的浸出浓度远远大于pH≥4.03时的浸出浓度。Pb、Cr、Zn随着浸出时间的增加，浸出浓度下降，而Cd、Ni上升，Cu是先上升后下降。在液固比、初始pH值及浸出时间这三个影响因素中，pH值对重金属的浸出影响较大，重金属在酸性环境下较易浸出。     

Determination of Lead in Dinnerware by an Ion Exchange Filter Paper ‐ X-Ray Fluorescence Method

Abstract

Lead leached from a variety of pottery dinnerware was determined by x-ray fluorescence after collecting and concentrating the lead on an ion exchange resin loaded filter paper disc. A 0.01 M HCl solution, to simulate acidic foodstuffs, used for the leaching was shown to have a leaching rate almost identical to that of white vinegar. The leaching rate increased with increasing temperature. The relative standard deviation for successive determinations of the same lead content was 1.8%, and the detection limit was 1.08 μg of total lead which corresponded to 0.0072 ppm when 150 ml of leaching solution was used.     

Leaching of the Anthraquinone Dye Solvent Blue 59 Incorporated into Organically Modified Silica Xerogels

The effects of preparation method and precursor composition on the leaching behavior of the anthraquinone dye Solvent Blue 59 incorporated into silica based xerogels have been studied. Xerogels were prepared under acidic conditions from mixtures of 20 mol% of organically modified silicon alkoxides, R–Si(OR)3, in Si(OR)4 (R = methyl or ethyl, R = methyl, vinyl, phenyl). The dye was added at the beginning of the sol-gel reaction. The reaction was carried out by either hydrolysis under acidic conditions or acidolysis by formic acid. The dye incorporated was leached with refluxing ethanol using a Soxhlet extraction procedure to simulate the long-term stability of the samples prepared. With increasing size of organic substituent (methyl < vinyl < phenyl), the amount of dye leached decreases. Results from nitrogen adsorption experiments show that all samples characterized have about the same average pore diameter, but they differ in total pore volume and BET surface area. With increasing size of the organic residue, the pore volume decreases by an order of magnitude. Therefore, it is concluded that the microstructure of the xerogels prepared determines the retention behavior of dyes incorporated during the sol-gel reaction.     

Adsorption of some bivalent heavy metal ions from aqueous solutions by manganese nodule leached residues

The leached residue, generated after selective extraction of Cu, Ni, and Co in sulfur dioxide-ammonia leaching of manganese nodules, was characterized and batch isothermal adsorption experiments were conducted at ambient temperature to evaluate the effectiveness of the water-washed leached residue for removal of different bivalent metal ions from aqueous synthetic solutions. The effects of pH, initial metal ion concentrations, amount of adsorbent, interfering ions, and heat treatment were also investigated. The uptake of metal ions increased with increasing pH. Under identical conditions the adsorption capacity increased in the order Cd(2+)相似文献   

On-line dynamic extraction and automated determination of readily bioavailable hexavalent chromium in solid substrates using micro-sequential injection bead-injection lab-on-valve hyphenated with electrothermal atomic absorption spectrometry

A novel and miniaturized micro-sequential injection bead-injection lab-on-valve (microSI-BI-LOV) fractionation system was developed for on-line microcolumn soil extraction under simulated environmental scenarios and accurate monitoring of the content of easily mobilisable hexavalent chromium in soil environments at the sub-low parts-per-million level. The flow system integrates dynamic leaching of hexavalent chromium using deionized water as recommended by the German Standard DIN 38414-S4 method; on-line pH adjustment of the extract by a 0.01 mol L(-1) Tris-HNO(3) buffer solution; isolation of the chromate leached from the matrix constituents onto a Q Sepharose strong anion-exchanger freshly packed into the microconduits of the microSI-assembly; air-segmented elution of the sorbed species by a 40 microL plug of 0.5 mol L(-1) NH(4)NO(3) (pH 8) eluent; and detection by electrothermal atomic absorption spectrometry (ETAAS). The effect of simulated acidic rain on the accessibility of chromate forms for plant uptake was also investigated. The proposed approach offers several advantages over conventional speciation/fractionation protocols in the batch mode, including immediate separation with concomitant preconcentration of the released chromate, minimization of Cr(vi) to Cr(iii) interconversion risks, enhanced accuracy, and non-existence of re-adsorption/re-distribution problems along with a detailed pattern of the kinetics of the leaching process. The reliability of the proposed method was evaluated via spiking of a moderately polluted agricultural soil material (San Joaquin Soil-Baseline Trace Element Concentrations) with water-soluble Cr(vi) salts at different concentration levels. The potential of the microSI-BI-LOV set-up with renewable surfaces for flame-AAS determination of high levels of readily bioavailable chromate in contaminated soils is also addressed.