Supported ionic liquid membranes for removal of dioxins from high-temperature vapor streams

Dioxins and dioxin-like chemicals are predominantly produced by thermal processes such as incineration and combustion at concentrations in the range of 10-100 ng of I-TEQ/kg (I-TEQ = international toxic equivalents). In this work, a new approach for the removal of dioxins from high-temperature vapor streams using facilitated supported ionic liquid membranes (SILMs) is proposed. The use of ceramic membranes containing specific ionic liquids, with extremely low volatility, for dioxin removal from incineration sources is proposed owing to their stability at very high temperatures. Supported liquid membranes were prepared by successfully immobilizing the ionic liquids tri-C(8)-C(10)-alkylmethylammonium dicyanamide ([Aliquat][DCA]) and 1-n-octyl-3-methylimidazolium dicyanamide ([Omim][DCA]) inside the porous structure of ceramic membranes. The porous inorganic membranes tested were made of titanium oxide (TiO(2)), with a nominal pore size of 30 nm, and aluminum oxide (Al(2)O(3)), with a nominal pore size of 100 nm. The ionic liquids were characterized, and the membrane performance was assessed for the removal of dioxins. Different materials (membrane pore size, type of ionic liquid, and dioxin) and different operating conditions (temperature and flow rate) were tested to evaluate the efficiency of SILMs for dioxin removal. All membranes prepared were stable at temperatures up to 200 °C. Experiments with model incineration gas were also carried out, and the results obtained validate the potential of using ceramic membranes with immobilized ionic liquids for the removal of dioxins from high-temperature vapor sources.     

Task-specific ionic liquids incorporating novel cations for the coordination and extraction of Hg2+ and Cd2+: synthesis,characterization, and extraction studies

A series of hydrophobic task-specific ionic liquids designed to extract Hg2+ and Cd2+ from water were prepared by appending urea-, thiourea-, and thioether-substituted alkyl groups to imidazoles and combining the resulting cationic species with PF6-. The new ionic liquids were characterized and investigated for their metal ion extraction capabilities. When used in liquid/liquid extraction of Hg2+ and Cd2+ from aqueous solutions, the metal ion distribution ratios increased several orders of magnitude, regardless of whether the ionic liquids were used as the sole extracting phase or doped into a series of [1-alkyl-3-methylimidazolium][PF6] (alkyl = n-C4-C8) ionic liquids to form a 1:1 solution. In the 1:1 mixtures, as the length of the alkyl chain increased from butyl to hexyl to octyl, the metal ion distribution ratios increased. Increasing the ratio TSIL/[C4mim][PF6] resulted in higher distribution ratios for both Hg2+ and Cd2+. Overall, the thiourea- and urea-derivatized cations yielded the highest distribution ratios, and those for Hg2+ were higher than those for Cd2+; however, a change in aqueous-phase pH does not promote the stripping of metal ions from the extracting phase. The combination of these imidazolium cations and PF6- produced ionic liquids with decreased thermal stability in comparison to [C(n)mim]-[PF6]. Gaussian98 restricted Hartree-Fock geometry optimizations for one of the thiourea-appended cations shows the charge delocalization around the ring and suggests that the thiourea group may aid in deprotonating the imidazolium ring and may be responsible for the lowered thermal stability of these cations.     

Use of pyrolysis GC/MS for predicting emission byproducts from the incineration of double-base propellant

Gas chromatography/mass spectrometry was used to analyze the pyrolytic byproducts from an Army-unique propellant compound (AA2) that is composed of predominantly nitrocellulose and nitroglycerin. Compounds produced by AA2 pyrolysis were compared to compounds detected in the gaseous effluent from AA2 incineration. The light permanent gases and most of the higher molecular weight byproducts produced by AA2 incineration are replicated by laboratory pyrolysis on AA2. The reverse case also holds whereby 18 out of 24 high molecular weight AA2 pyrolytic byproducts are found in the incinerator emissions. Poor matching, however, was obtained between the two processes for the volatile, water-soluble species. None of these low molecular weight compounds produced under pyrolytic conditions were detected in the AA2 incinerator samples, likely indicating inefficient capture of these compounds from the effluent stream. Separate pyrolytic degradation of the individual components of AA2 provides evidence that nearly all of the incomplete combustion products detected during incineration originate not from the prevalent energetic ingredients but rather from the minor and trace additives in AA2. In addition, pyrolysis successfully identified the AA2 components capable of surviving the incineration process intact. This work illustrates the potential of bench-scale pyrolysis for predicting incineration behavior.     

Factors affecting ionic liquids based removal of anionic dyes from water

Liquid--liquid extraction with imidazolium based ionic liquids--[C4mim][PF6], [C6miml][PF6], [C6mim[BF4], and [C8mim][PF6--is proposed for removal of anionic dyes including methyl orange, eosin yellow, and orange G from aqueous solutions. The effects of extraction time, pH of aqueous phase, structure of the ionic liquids, temperature, and KCl concentration on the extraction efficiencies have been studied. Extraction efficiencies of dyes were strongly affected by the pH of the aqueous phase. Under the optimized pH condition, 85-99% of methyl orange, almost 100% eosin yellows, and 69% of orange G in tested water samples were transferred into the ionic liquids in a single extraction. Extraction efficiency for a given dye was found to increase with increasing temperature and increasing alkyl chain length of cation of the ionic liquids. Presence of a small amount of KCl in the aqueous phase did not considerably improve the extraction efficiency of the dyes. Thermodynamic studies revealed that the extraction process was driven by hydrophobic interaction of the anionic dyes and the ionic liquids.     

Preliminary assessment of imidazolium-based room-temperature ionic liquids for extraction of organic contaminants from soils

Alternative solvents known as room-temperature ionic liquids (RTILs) were considered for extraction of organic soil contaminants. A hydrophobic RTIL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([bmim]PF6), and a hydrophilic RTIL, 1-butyl-3-methyl imidazolium chloride ([bmim]Cl), were selected as representative imidazolium-based RTILs to assess the extraction of several organic contaminants (OCs) from two model soils. The two soils were montmorillonite (clay minerals, high surface area, and no organic matter) and glacial till (organic matter). The soils were spiked separately with DDT, dieldrin, hexachlorobenzene, and pentachlorophenol. With the exception of DDT, extractions of OCs from montmorillonite using [bmim]PF6 (79-92%) were nearly as effective as extractions with acetone and ethanol (85-100%). The extraction of OCs from glacial till with RTILs (15-61%) was less effective than extraction with organic solvents (59-100%). The [bmim]Cl was as efficient as [bmim]PF6 for extraction of OCs from glacial till, while [bmim]PF6 was more efficient than [bmim]Cl for extraction of OCs from montmorillonite. The two RTILs were most effective for the extraction of dieldrin (the heaviest OC) from both soils. The extraction results for glacial till showed dependence of OC extraction on the viscosity and melting point of RTILs.     

离子液体辅助双水相系统提取茶渣中茶多酚工艺优化

为发展一种绿色、高效及温和的茶多酚提取方法,采用离子液体(IL)辅助乙醇/硫酸铵双水相系统(ATPS)提取茶渣中的茶多酚,考察了离子液体结构和用量对茶多酚得率和抗氧化性的影响,对提取工艺进行了正交试验优化。结果显示,少量IL添加可提高乙醇/硫酸铵ATPS的分相能力及其对茶多酚的得率,但对提取液的抗氧化活性没有明显影响;咪唑型离子液体对提取茶多酚具有更好的促进作用,咪唑环上侧链越长,其茶多酚得率越高;[C₄mim]Cl辅助乙醇/硫酸铵ATPS对茶渣中茶多酚得率明显高于其他体系,且其提取液中儿茶素类组分含量更高。茶渣多酚最佳提取工艺为[C₄mim]Cl质量分数10%、硫酸铵质量分数30%、乙醇体积分数60%,料液比1∶40 g/mL及超声功率540 W,在此条件下,茶渣中茶多酚得率为85.31±1.25 mg·g-1。IL辅助双水相系统是一种有前景的茶多酚提取工艺,在保持茶多酚活性的同时,能获得较高的茶多酚得率和儿茶素类组分含量。     

Novel incineration technology integrated with drying, pyrolysis, gasification, and combustion of MSW and ashes vitrification

The conventional mass burn systems for municipal solid waste (MSW) emit large amount of acidic gases and dioxins as well as heavy metals due to the large excess air ratio. Additionally, the final process residues, bottom ash with potential leachability of heavy metals and fly ash with high level of heavy metals and dioxins, also constitute a major environmental problem. To deal with these issues more effectively, a novel MSW incineration technology was developed in this study. MSW drying, pyrolysis, gasification, incineration, and ash vitrification were achieved as a spectrum of combustion by the same equipment (primary chamber) in one step. In practice, the primary chamber of this technology actually acted as both gasifier for organic matter and vitrifying reactor for ashes, and the combustion process was mainly completed in the secondary chamber. Experiments were carried outto examine its characteristics in an industrial MSW incineration plant, located in Taiyuan, with a capability of 100 tons per day (TPD). Results showed that (1) the pyrolysis, gasification, and vitrification processes in the primary chamber presented good behaviors resulting in effluent gases with high contents of combustibles (e.g., CO and CH4) and bottom ash with a low loss-on-ignition (L.o.l), low leachability of heavy metals, and low toxicity of cyanide and fluoride. The vitrified bottom ash was benign to its environment and required no further processing for its potential applications. (2) Low stack emissions of dioxins (0.076 ng of TEQ m(-3)), heavy metals (ranging from 0.013 to 0.033 mg m(-3)), and other air pollutants were achieved. This new technology could effectively dispose Chinese MSW with a low calorific value and high water content; additionally, it also had a low capital and operating costs compared with the imported systems.     

Characterization and inventory of PCDD/Fs and PBDD/Fs emissions from the incineration of waste printed circuit board

Many developing countries have not significantly changed their course with regard to electronic waste contamination, and they are still facing the specter of mountains of hazardous electronic waste, with serious consequences for both the environment and public health. An efficient and stable analytical method was developed to determine the inventory and emission factors of polybrominated dibenzo-p-dioxin and dibenzofurans (PBDD/Fs) and polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) formed from the incineration of scrap printed circuit boards (PCBs). Both PBDD/Fs and PCDD/Fs have been found in all experimental sections with a maximum formation rate at temperatures between 250 and 400 °C. The amounts tended first to increase and then began to decrease as the temperature rose. When subjected to a heating temperature of 325 °C, the total content of twelve 2,3,7,8-substituted PBDD/Fs congeners (tetra- through octabromo-) gathered from three outputs was the largest, at 19?000, 160?000, and 57 ng TEQ/kg in solid, liquid, and gaseous fractions, respectively; the total content of seventeen 2,3,7,8-substituted PCDD/Fs congeners (tetra- through octachloro-) was 820, 550, and 1.4 ng TEQ/kg. The formation of PCDD/Fs was remarkably less than that of PBDD/Fs because bromine concentrations considerably exceeded chlorine concentrations. The ingredients and conditions necessary to form PCDD/Fs or PBDD/Fs were definitely present, such as products of incomplete combustion, halogenides, an oxidizing atmosphere, and a catalyst-Cu salts being the most effective, significantly increasing the yields of PCDD/Fs and PBDD/Fs and decreasing the optimum temperature range.     

活性艳橙K-7R结合丝素肽的分子光谱学特征

本文通过紫外可见、荧光光谱、同步荧光、瑞利散射共振光谱等分子光谱技术研究发现,活性艳橙K-7R(RK-7R)与丝素肽结合为1:1、作用距离为3.46nm的非荧光性复合物。活性艳橙K-7R印染体系中可能存在的阳离子表面活性剂CTAB、3种离子液体（溴化1-乙基-2,3-二甲基咪唑、1-乙基-2,3-甲基咪唑双三氟甲磺酰亚胺盐、氯化羟乙基三甲基胺）,3种金属离子（Ca2+、Pb2+、Ba2+）都增强了丝素肽与活性艳橙K-7R的结合;而非离子型表面活性剂曲拉通X-100以及Cu2+均削弱二者结合,阴离子表面活性剂十二烷基磺酸钠对二者结合不影响。     

咪唑类离子液体提取天然产物的应用研究

离子液体因具有良好的溶解性、热稳定性、化学稳定性、可设计性等特点,在提取分离天然产物方面具有显著的提取效果。本文综述了近年来咪唑类离子液体作为提取剂在提取天然产物方面的应用,提出了离子液体在分离天然产物领域中存在的问题,并指出安全、功能化离子液体的研制和离子液体的高效回收是解决这些问题的主要手段,为离子液体在天然产物提取中的应用奠定基础。     

烷基咪唑类双子型离子液体对涤纶织物的碱减量处理

为开发新型涤纶碱减量促进剂及其应用工艺,提高涤纶碱减量的加工效率,采用3种烷基咪唑类双子型Gemini离子液体作为涤纶碱减量加工促进剂,并与常规阳离子促进剂十二烷基二甲苄基氯化铵进行对比,探究了促进剂和氢氧化钠用量、碱减量处理温度和时间等因素对涤纶减量率的影响,测试了碱减量处理前后涤纶的强力和形貌。结果表明：烷基咪唑类Gemini促进剂可用于涤纶纤维的碱减量加工,且相同结构的促进剂对涤纶纤维的促进作用符合Traube规则;促进剂疏水性越强,涤纶的减量率越高;促进剂的加入可降低氢氧化钠的用量,促进涤纶纤维的碱减量,且碱减量加工后涤纶表面形成凹槽,纤维变细,比表面积增大。     

烷基链改变对吡啶类离子液体的性能影响

离子液体是一类新型软功能材料,在多相催化、萃取分离、材料制备等领域具有重要的研究意义.本文基于吡啶环上烷基链的分子结构设计,分别以溴代烷(CnH2n-1Br,n=4,8,12)、吡啶和六氟磷酸钾为反应物,获得了3种不同烷基结构的疏水性吡啶类离子液体[Cnpyr][PF6].研究表明,直链烷基吡啶类离子液体的熔点随着吡啶环上烷基链的增长,出现先降低后升高的趋势,其热分解温度在370℃左右.在室温下测定了[Cnpyr][PF6]离子液体的电导率,通过非线性最小二乘法对测得数据进行拟合,得到了[Cnpyr][PF6](n=4,8,12)的电导率与浓度之间的函数关系,其拟合的标准偏差分别为0.002 39μs/cm,0.004 47μs/cm,0.004 78μs/cm.最后,[Cnpyr][PF6]属于典型的疏水性离子液体,烷基链长度的改变对溶解性的影响相对较小.     

Investigation of novel incineration technology for hospital waste

Conventional incineration systems for hospital waste (HW) emit large amounts of particulate matter (PM) and heavy metals, as well as dioxins, due to the large excess air ratio. Additionally, the final process residues--bottom and fly ashes containing high levels of heavy metals and dioxins--also constitute a serious environmental problem. These issues faced by HW incineration processes are very similar to those confronted by conventional municipal solid waste (MSW) incinerators. In our previous work, we developed a novel technology integrating drying, pyrolysis, gasification, combustion, and ash vitrification (DPGCV) in one step, which successfully solved these issues in MSW incineration. In this study, many experiments are carried out to investigate the feasibility of employing the DPGCV technology to solve the issues faced by HW incineration processes, although there was no MSW incinerator used as a HW incinerator till now. Experiments were conducted in an industrial HW incineration plant with a capacity of 24 tons per day (TPD), located in Zhenzhou, Henan Province. Results illustrated that this DPGCV technology successfully solved these issues as confronted by the conventional HW incinerators and achieved the expected results for HW incineration as it did for MSW incineration. The outstanding performance of this DPGCV technology is due to the fact that the primary chamber acted as both gasifier for organic matter and vitrifying reactor for ashes, and the secondary chamber acted as a gas combustor.     

大黄提取物中5种蒽醌化合物的分离纯化

为研究大孔树脂对大黄5种蒽醌的分离效果,本文采用静态吸附实验,比较6种大孔树脂(HPD-100、XDA-6、AB-8、LX-38、ADS-7和ADS-17)对5种游离蒽醌(芦荟大黄素、大黄酸、大黄素、大黄酚、大黄素甲醚)的吸附及解吸附性能,筛选出对大黄5种蒽醌吸附率和吸附率最高的大孔树脂。然后以筛选的大孔树脂作为载体,对其动态吸附特性进行了初步研究。结果显示,HPD-100大孔树脂对大黄5种蒽醌吸附率和吸附率最高;在层析柱径高比1:8,上样溶液5种蒽醌总浓度为3.64 mg/mL,上样体积2.0 BV,流速1.0 BV/h,85%的乙醇洗脱,洗脱体积为3.0 BV的优化条件下,HPD-100对5种蒽醌的动态吸附率为86.3%,洗脱率为85.9%,5种蒽醌总含量增加了2.88倍,由原来的7.13％增加到20.5％,总回收率98.7%,提取物中残留的离子液体[bmim]Br也同时被除去,表明本实验选择的优化条件具有可行性。     

新型不对称咪唑类离子液晶化合物的微波法合成和液晶性能研究

使用微波辅助的方法高效合成了两种未见报道的不对称咪唑盐类离子液晶化合物,1-[4-(十二烷氧基)苯基]-3-己基咪唑溴盐和1-[4-(十二烷氧基)苯基]-3-辛基咪唑溴盐,并通过POM和DSC对它们的液晶性能进行了充分研究。实验表明,两种咪唑盐呈现出典型的和良好的近晶相织构。     

复配离子液体匀染剂在腈纶染色中的应用

合成了三种不同阴离子结构的离子液体,并将其应用在腈纶染色工艺中。结果表明,离子液体具有较好的匀染作用,且由于离子液体可调的酸碱性,可避免酸碱盐等传统助剂的使用。优化的复配离子液体染色工艺为:1%(omf)的[BMim]HSO4和[BMim]BF4复配离子液体,将pH值控制在4~5,可实现阳离子染料均匀上染腈纶织物,通过测定染料上染速率曲线证实了离子液体的缓染性。     

Toxicity of ionic liquids and organic solvents to lactic acid-producing bacteria

In situ extractive fermentation of lactic acid using organic solvents has already been extensively investigated. Now ionic liquids are emerging as alternative solvents for volatile organic compounds traditionally used in liquid-liquid extraction. In this study, we examine whether lactic acid producing-bacteria can grow in the presence of a second phase of imidazolium-based ionic liquids or organic solvents. The lactic acid producing-bacteria used in this study are sensitive to organic solvents having 1 < log P < 4. We found that Lactobacillus delbruekii subsp. lactis NRIC 1683 could grow in the presence of a second phase of imidazolium-based ionic liquids as well as in the absence of the ionic liquids.     

纤维素在咪唑基离子液体中的降解行为

为了解纤维素在咪唑类离子液体中的降解行为,用正交试验法分析了温度、转速、时间对纤维素降解程度的影响,并比较了纤维素在四种离子液体中的降解行为。结果表明,纤维素在1-乙基-3-甲基咪唑醋酸盐（[EMIM]Ac）中的最佳溶解条件为,温度80℃,时间1h,转速230r/min。温度对纤维素降解程度影响最大,其次为时间和转速。同条件下,纤维素在[EMIM]Ac中的降解最轻,在1-烯丙基-3-甲基咪唑氯盐（[AMIM]Cl）中降解最严重。没食子酸丙酯可显著缓解纤维素在离子液体中的降解程度。[EMIM]Ac、1-丁基-3-甲基咪唑醋酸盐（[BMIM]Ac）遇没食子酸丙酯显紫红色,并在纤维素溶解后颜色消失。     

Brφnsted酸性离子液体催化合成油酸甲酯的研究

合成并表征了N-甲基-2-吡咯烷酮硫酸氢盐([Hnmp]HSO4)、N-甲基咪唑硫酸氢盐([Hmim]HSO4) 2种阴离子Brφnsted酸性离子液体,考察了这2种离子液体在催化油酸和甲醇酯化反应中的催化活性.结果表明,离子液体的催化活性与其酸性密切相关;当离子液体[Hnmp]HSO4用量为油酸质量的5%,n(甲醇):n(油酸)为1.5:1,反应温度75 ℃,反应时间3 h时,酯化率可达98%以上.反应结束后离子液体与酯化产物成两相,而且离子液体[Hnmp]HSO4重复使用5次,仍有较高的催化活性.     

Formation of dioxins from incineration of foods found in domestic garbage

There has been great concern about the large amounts of garbage produced by domestic households in the modern world. One of the major sources of dioxins (PCDDs, PCDFs, and coplanar PCBs) in the environment is the combustion of domestic waste materials. Exhaust gases from an incinerator, in which mixtures of 67 food items--including fruits, vegetables, pasta, seafoods, meats, and processed foods and seasoned foods--were analyzed for dioxins. Gases collected at the chimney port (9.15 ng/g) contained less total dioxins than those collected at the chamber port (29.1 ng/g). The levels of Cl1-Cl6-PCDDs and Cl1-Cl5-PCDFs were much lower in the gas collected at the chimney port than in the gas collected at the chamber port. The levels of Cl7-Cl8-PCDDs and Cl6-Cl8-PCDFs were higher in the gas collected at the chimney port than in the gas collected at the chamber port. A total of Cl4-Cl8-PCDDs (1.84-3.04 ng/g) comprised over 80% of the total PCDDs formed (2.24-4.00 ng/g). Total PCDFs (16.2-22.6 ng/g) comprised 78-86% of the total dioxins formed (18.9-29.1 ng/g). The PCDFs formed in the greatest amounts were M1CDFs (9.68-10.7 ng/g). Mixtures of commonly consumed food items produced ppb levels of total dioxins in exhaust gases upon combustion, suggesting that incineration of domestic food wastes is one of the sources of dioxins in the environment. A mixture containing some seasoned foods, such as mayonnaise spread on bread, produced more dioxins (29.1 ng/g) than a mixture without seasoned foods did (18.9 ng/g).