高硫石油焦喷射脱汞实验研究

以Na_2S与NH4Br溶液分别对石化工业副产物高硫石油焦进行活化,改性以制成载溴富硫活性炭。采用比表面积及孔隙度分析仪、扫描电子显微镜/X射线能谱分析仪、X射线光电子能谱仪对吸附剂物理化学性质进行表征。在模拟烟气管道喷射实验装置上进行了高硫石油焦喷射脱汞实验研究。结果表明,Na_2S活化后的石油焦表面微孔结构和微观形貌得到较大改善,在石油焦表面形成含硫官能团;NH4Br改性后使溴活性因子搭载于石油焦表面,促进了临近含硫官能团的活性;表面含硫官能团与溴活性因子的共同作用使高硫石油焦表现出较强的汞吸附脱除能力,可作为燃煤烟气喷射脱汞吸附剂。     

溴化铜改性硅藻土脱汞性能的实验研究

采用溴化铜(CuBr2)对三种硅藻土(Dia)进行改性得到脱汞吸附剂(CuBr2-Dia1、CuBr2-Dia2、CuBr2-Dia3),在固定床实验装置上研究了所制备的吸附剂的脱汞性能,并研究了不同温度和烟气组分对CuBr2-Dia3脱汞效率的影响.实验结果表明,改性后三种硅藻土的脱汞性能都有显著提高,以CuBr2-Dia3的脱汞效率最高.在纯氮气下CuBr2-Dia3的最佳脱汞温度为140℃.所吸附的汞至少存在两种形态,并且具有很好的热稳定性.O2和HCl共同作用可以提高CuBr2-Dia3的脱汞性能。NO也具有很强的促进作用.在纯氮气下加入0.03%NO后,CuBr2-Dia3的脱汞效率由原来的92.5%提高到96.0%。SO2具有明显的抑制作用,0.12%SO2能将其脱汞效率降低到59.7%,而加入4%O2和0.03%NO后,其脱汞效率又恢复到原来的水平。     

活性炭表面含氧官能团对汞吸附的作用

本文对采用不同方法处理后的活性炭进行BET、官能团分析和汞吸附性能实验,研究其表面含氧官能团对汞吸附的作用。结果表明:活性炭表面的酯基与羰基能提高汞的吸附效率,高于100℃时是影响活性炭汞吸附效率的主要因素。物理吸附,羰基与酯基吸附的汞的程序升温脱附温度峰值分别为100,210和320℃。汞在与活性炭表面接触后优先被吸附能高的化学吸附位点吸附,化学吸附饱和后,才会进行物理吸附。     

溴素改性活性炭汞吸附特性研究

在固定床实验台上进行了1%NH_4Br改性活性炭汞吸附实验。利用吸附动力学模型从动力学角度探讨了汞吸附速率控制步,汞吸附活化能与初始汞吸附速率。结果表明:150℃时,1%NH_4Br改性活性炭脱汞能力显著增强,其原因是改性后活性炭表面活性位点(Br)明显增加,强化了化学吸附作用。但低温时,化学吸附增强作用不明显。汞在改性活性炭表面的吸附活化能为29.69 kJ/mol,说明吸附以物理吸附为主,化学吸附为辅。改性活性炭的初始汞吸附速率随温度增加而增加。活性位吸附是汞吸附速率控制步,外部传质控制也影响整个汞吸附过程,吸附遵循Langmuir吸附等温方程。     

改性煤基活性炭对燃煤烟气中汞的脱除

本文以无烟煤为前驱体,采用KOH活化法制备了煤基活性炭,并以NH4I为改性剂对活性炭进行改性,用于燃煤烟气中汞的脱除。实验研究了负载的NH4I的质量分数、烟气温度以及烟气成分对改性活性炭脱汞性能的影响。研究结果表明,最佳的NH4I负载质量分数为0.07;在80~180℃的温度范围内,随着温度的升高,活性炭的脱汞效率逐渐降低。烟气中的O2、CO2、NO、HCl等组分对改性后的活性炭的脱汞效率具有一定的促进作用,SO2则有明显的抑制作用;但由于改性活性炭具有较好的抗硫效果,当烟气中含有微量的SO2时,活性炭的平均脱汞效率仍可达到87.95%。采用热再生法对改性活性炭进行再生,结果表明,400℃下再生的活性炭的脱汞率为95.82%,但随着再生次数的增加,活性炭脱汞效率不断降低。     

载硫椰壳活性炭喷射脱汞实验研究

以元素硫对椰壳活性炭在不同温度下进行载硫改性。采用N2吸附/脱附、X射线近边吸收结构等方法对吸附剂进行孔隙结构和硫存在形态表征。在模拟烟气管道喷射实验装置上进行汞吸附脱除实验研究。载硫温度500℃时椰壳活性炭汞吸附效率优于商用富硫活性炭。活性炭汞吸附脱除能力由孔隙结构、硫含量与存在形态共同决定。不同体积分数SO_2、NO和HCl的加入对活性炭均有不同程度的促进作用。     

过渡金属卤化物改性非碳基吸附剂脱汞研究

以6种大比表面积非碳基成分为载体,经过渡金属卤化物改性处理后制成汞吸附剂,并对其不同烟气气氛和温度下的汞吸附性能及汞氧化率进行了研究。CuCl_2改性氧化铝在各种烟气条件下均表现出较好的汞吸附性能。FeCl_3改性沸石的汞脱除率相对略低,但它制作成本较低。这两种非碳基吸附剂在未来有较好的应用前景。改性吸附剂的最适宜反应温度100～200℃。     

纳米硫化铜烟气脱汞及其机理研究

本研究采用沉淀法制备纳米硫化铜(nano-CuS),并评价了其汞吸附性能。nano-CuS最佳脱汞反应温度为75℃,适用于在FGD和WESP区间内喷射脱汞,避免高浓度酸性气体(SO_2、NO)对脱汞性能的干扰.在N_2,N_2+4%O_2、以及模拟烟气条件下,nano-CuS的吸附容量和吸附速率达到89.43～122.40 mg·g~(-1)及11.93～13.56μg·g~(-1)·min~(-1),与文献报道的金属硫化物吸附剂相比至少高一个量级。通过汞程序升温脱附实验和系统的表征发现,nano-CuS中的硫以多态的形式存在,特别是多硫的含量明显高于文献报道的金属硫化物吸附剂。除此之外,由于铜与汞之间的强相互作用,铜活性位点同样参与到了气态汞的吸附当中,从而使得nano-CuS具有非常优异的汞吸附能力。该研究不仅可以为多硫汞吸附剂的简单化制备提供思路,还提供了一种有潜力的非炭基汞吸附剂。     

磁性可再生天然铁矿石吸附剂对汞的脱除研究

选取磁性天然铁矿石作为燃煤烟气中的汞吸附剂,采用XRD、BET、XRF和VSM表征方法对天然铁矿石的物理化学特性进行表征,在模拟烟气下采用固定床反应器研究铁矿石的脱汞性能、吸附反应机理和循环再生性能。结果表明:在低温时天然铁矿石吸附剂具有90%以上的脱汞效率,100℃时脱汞效率最佳,达到96.67%.汞在铁矿石表面的吸附方式主要是化学吸附,生成的汞形态主要是HgCl_2和HgO。10次吸附-循环再生中脱汞效率均在80%以上。     

纳米硫化锌吸附脱除单质汞的实验研究

在固定床吸附实验台上研究了N_2气氛下纳米硫化锌(Nano-ZnS)对单质汞的吸附脱除特性,分析了锌硫比(Zn:S)和干燥温度等制备条件以及反应床温度对其脱汞效果的影响,并和活性炭的脱汞性能进行对比。结果表明:锌硫比和干燥温度对吸附剂的脱汞性能影响很大,锌硫比为1:0.98,干燥温度为160℃时制备出的纳米硫化锌的脱汞性能最佳;纳米硫化锌对汞的吸附以化学吸附为主,在200℃左右,吸附作用最强;与商业活性炭相比,纳米硫化锌具有更优秀的汞吸附能力以及吸附速率。     

Hexagonal mesoporous silica modified with 2-mercaptothiazoline for removing mercury from water solution

A method for the attachment of 2-mercaptothiazoline (MTZ) to modified silica gel has been developed. In the first step, a new silylant agent was synthesized, named SiMTZ, by the reaction between MTZ molecule and chloropropyltrimethoxysilane (SiCl). SiMTZ and tetraethylortosilicate were co-condensed in the presence of n-dodecylamine, a neutral surfactant template, to produce a modified ordered hexagonal mesoporous silica named HMTZ. The modified material contained 0.89 ± 0.03 mmol of 2-mercaptothiazoline per gram of silica. FT-IR, FT-Raman, ²⁹Si- and ¹³C-NMR spectra were in agreement with the proposed structure of the modified mesoporous silica in the solid state. HMTZ material has been used for divalent mercury adsorption from aqueous solution at 298 ± 1 K. The series of adsorption isotherms were adjusted to a modified Langmuir equation. The maximum number of moles of mercury adsorbed gave 2.34 ± 0.09 mmol/g of material. The same interaction was followed by calorimetric titration on an isoperibol calorimeter. The HMTZ presented a high capacity for the removal of the contaminant mercury from water. The ΔH and ΔG values for the interaction were determined to be −56.34 ± 1.07 and −2.14 ± 0.11 kJ mol⁻¹. This interaction process was accompanied by a decrease of entropy value (−182 J mol⁻¹ K⁻¹). Thus, the interaction between mercury and HMTZ resulted in a spontaneous thermodynamic system with a high favorable exothermic enthalpic effect.     

通透结构泡沫硒化铜原位构筑及烟气脱汞研究

燃煤烟气汞的大量排放对公众健康和生态系统造成了严重威胁,开发新型高效脱汞技术和材料对汞污染防治具有重要意义。本文采用原位硒化方法制备了泡沫硒化铜(Cu-hs),与采用水热法制备的泡沫硒化铜(Cu-hd-1和Cu-hd-12)相比,Cu-hs具有更优的单质汞(Hg⁰)吸附性能。Cu-hs具有良好的抗H₂O和SO₂干扰能力,O₂对Cu-hs吸附Hg⁰有一定的促进作用,而HCl的存在对Hg⁰吸附没有明显影响。Cu-hs表面的汞饱和吸附量为3743 g/m³(约为15 mg/g),显著高于目前文献中报道的活性炭的饱和吸附量,具有很好的燃煤烟气脱汞应用潜力。     

汞在Ti2NO2 MXene表面吸附氧化的第一性原理计算

汞是一种有毒的重金属，在生产生活中以各种形式排放的汞对生态及人类健康都存在一定程度的威胁.因此，寻找高效的汞吸附剂具有十分重要的意义.本文基于密度泛函理论的第一性原理计算方法，研究了汞在Ti₂NO₂(MXene)和具有一个氧空位缺陷的Ti₂NO₂(Ov-Ti₂NO₂)上的吸附和氧化机理.计算结果表明Hg⁰在Ti₂NO₂表面的吸附为物理吸附，在Ov-Ti₂NO₂表面为化学吸附. Ti₂NO₂表面氧空位的存在可以改善HgO与Ov-Ti₂NO₂之间的相互作用，从而使吸附能提高116 kJ/mol. Hg⁰在Ov-Ti₂NO₂表面氧化为HgO的反应能垒为92.55 kJ/mol,小于其在Ti_2<...     

Optimal Microwave Radiation Field Parameters for Mercury Ion Microwave Frequency Standards

We propose a method to determine the optimal power of the microwave resonance transition that simultaneously improves the signal-to-noise ratio and reduces line width based on saturation broadening theory and experiment.Saturation broadening spectra of the ground state hyperfine transition of trapped ~(199)Hg~+ ions are measured and analyzed.The value of the optimal microwave power is obtained by using the proposed method and is verified.Rabi oscillations decay spectra of trapped ~(199)Hg~+ ions are observed and the optimal microwave irradiation time for the maximum transition signal intensity is determined.This work will help to improve the short-term frequency stability of the mercury ion microwave frequency standard.     

Removal and recovery of mercury from aqueous solution using magnetic silica nanocomposites

Thiol-functionalized magnetic silica nanocomposite was synthesized and tested for its mercury pick-up capability in aqueous solution. Magnetic property was to be utilized upon the collection of the adsorbents and the recovery adsorbed Hg by subsequent separation process. Cobalt ferrite nanoparticle, the core of magnetic silica nanocomposite, was synthesized using a thermal decomposition method and grown to a particle having an average size of 13 nm. The dispersed nanoparticles were then further arranged into spherical groups using a nanoemulsion method to enhance the reactivity toward magnets followed by tetraethyl orthosilicate coating using a modified Stöber method. The pore structure was modified by an additional coating of cetyltrimethylammonium bromide and tetraethyl orthosilicate. Finally, the surface of the magnetic silica nanocomposite was functionalized with thiol group. When tested for mercury adsorption capacity, a sufficiently high Hg adsorption capacity of 19.79 mg per g of adsorbent was obtained at room temperature and a pH of 5.5.     

未燃尽炭表面吸附汞的机理研究

本文应用量子化学密度泛函理论B3PW91方法,在lanl2dz基组水平上研究了飞灰中未燃尽炭表面对汞的微观吸附机理.建立了表征未燃尽炭的饱和簇模型,讨论了该簇模型在不同的情况下对汞的吸附作用,计算得出吸附能,并做出了相关的实验解释.结果表明量子化学的理论计算是揭示汞等痕量元素的吸附机理以及筛选合适吸附剂的一种有效方法.     

Roles of γ-Fe2O3 in fly ash for mercury removal: Results of density functional theory study

First-principle calculations based on density function theory (DFT) are used to clarify the roles of γ-Fe₂O₃ in fly ash for removing mercury from coal-fired flue gases. In this study, the structure of key surface of γ-Fe₂O₃ is modeled and spin-polarized periodic boundary conditions with the partial relaxation of atom positions are employed. Binding energies of Hg on γ-Fe₂O₃ (0 0 1) perfect and defective surfaces are calculated for different adsorption sites and the potential adsorption sites are predicted. Additionally, electronic structure is examined to better understand the binding mechanism. It is found that mercury is preferably adsorbed on the bridge site of γ-Fe₂O₃ (0 0 1) perfect surface, with binding energy of −54.3 kJ/mol. The much stronger binding occurs at oxygen vacancy surface with binding energy of −134.6 kJ/mol. The calculations also show that the formation of hybridized orbital between Hg and Fe atom of γ-Fe₂O₃ (0 0 1) is responsible for the relatively strong interaction of mercury with the solid surface, which suggests that the presently described processes are all noncatalytic in nature. However, this is a reflection more of mercury's amalgamation ability.     

Regeneration of thiol-functionalized mesostructured silica adsorbents of mercury

The regeneration of thiol-functionalized SBA-15 adsorbents of mercury is presented in this article. The influence of temperature and pH on the adsorption process was studied. The effect due to the presence of complexing agents in aqueous solution on the desorption step was also evaluated. Hg(II) maximum adsorption capacities at different temperatures ranging from 20 °C to 60 °C were obtained and it was found that temperature does not affect the adsorption process. Mercury adsorption capacity was also determined in the presence of HNO₃ and HCl up to 3 M concentration. The comparison of the results showed that whereas hydrochloric acid exhibits an appreciable capacity to regenerate the thiol-functionalized SBA-15 adsorbent, the nitric acid results inefficient. The difference was attributed to the mercury complexing ability of chloride anion. Four complexing compounds, KBr, KSCN, (NH₂)₂CS, and HBr were tested for desorbing mercury in regeneration experiments. All agents were able to remove significant amounts of adsorbed mercury, being hydrobromic acid the complexing compound that yields the best results.     

硫氰酸铵-十二烷基二甲基苄基氯化铵-水体系浮选分离汞(Ⅱ)

研究了硫氰酸铵-十二烷基二甲基苄基氯化铵-水体系浮选分离汞(Ⅱ)的行为及其常见金属离子的分离条件。控制pH=5.0,当0.01mol/L硫氰酸铵溶液和0.01mol/L十二烷基二甲基苄基氯化铵(DDBAC)溶液的用量分别为0.30、0.50mL时,体系中形成的不溶于水的三元缔合物(DDBAC)2[Hg(SCN)4]可浮于水相上层形成界面清晰的液-固两相,分相过程中,Hg2+被定量浮选,而Zn2+,Cd2+,Mn2+,Ni2+,Co2+,Fe2+等离子在此条件下不被浮选,实现了Hg2+的定量分离。该方法对合成水样中微量Hg2+进行定量浮选分离测定,浮选率为96.0%—108.8%。     

Mercury removal from aqueous solution and flue gas by adsorption on activated carbon fibres

The use of two activated carbon fibres, one laboratorial sample prepared from a commercial acrylic textile fibre and one commercial sample of Kynol^®, as prepared/received and modified by reaction with powdered sulfur and H₂S gas in order to increase the sulfur content were studied for the removal of mercury from aqueous solution and from flue gases from a fluidized bed combustor. The sulfur introduced ranged from 1 to 6 wt.% depending on the method used. The most important parameter for the mercury uptake is the type of sulfur introduced rather than the total amount and it was found that the H₂S treatment of ACF leads to samples with the highest mercury uptake, despite the lower sulfur amount introduced. The modified samples by both methods can remove HgCl₂ from aqueous solutions at pH 6 within the range 290-710 mg/g (ACF) which can be favourably compared with other studies already published. The use of a filter made with an activated carbon fibre modified by powdered sulfur totally removed the mercury species present in the flue gases produced by combustion of fossil fuel.