城市生活垃圾焚烧体系化学热力学平衡分析

采用化学热力学平衡分析方法，分析城市生活垃圾焚烧体系污染物的排放特性。主要计算了聚氯乙烯（PVC）及典型城市垃圾焚烧过程氯元素的化学平衡组成及其浓度，同时研究了脱氯剂对PVC及垃圾中氯转化的影响。计算结果表明，PVC热态反应的主要产物是HCl气体，在加入脱氯剂后温度低于600℃时，脱氯剂对HCl的脱除作用很明显；城市生活垃圾热解和燃烧过程中在温度超过600 ℃，垃圾中的有机氯和无机氯都将转化为HCl气体，而此时脱氯剂失去效果。由计算结果得到控制HCl生成，消除二口恶英污染物的生成反应工艺条件。     

工业热过程中无意产生的持久性有机污染物生成机理

持久性有机污染物(persistent organic pollutants,POPs)可在工业热过程中无意生成和被排放,而探究其生成机理是发展源头减排技术的基础.本文在梳理文献的基础上,发现二(噁)英的生成理论有了一些新的突破.关于氯酚和氯苯等前驱体在热过程中生成自由基中间体的研究,能够从分子层面上揭示二(噁)英的生...     

纳米Fe0降解2,4-二氯酚的影响因素及其机理

采用化学还原法制备了纳米Fe⁰, 并研究了不同条件下纳米Fe⁰对2,4-二氯酚(2,4-DCP)的降解情况, 探讨了纳米Fe⁰降解2,4-二氯酚的反应途径. 结果表明, 纳米Fe⁰对2,4-二氯酚的去除作用包括吸附、脱氯、开环三种机制. 其中脱氯作用是一种界面反应, 发生在氯酚分子被吸附到Fe原子表面之后. 2,4-二氯酚可以脱去一个氯原子生成2-氯酚或4-氯酚, 也可以脱去两个氯原子生成苯酚. 随着氯酚初始浓度的增大, 其相对去除率略有降低, 但绝对降解量有较大提高. 温度不仅影响脱氯速率, 而且影响氯酚的去除途径. 温度较高时脱氯作用占主导地位, 先脱氯后开环, 温度较低时吸附作用占主导地位, 较易发生先开环后脱氯的情况.     

木屑焚烧过程中氯化氢排放特性研究

在小型管式炉进行了含氯垃圾(木屑)中氯化物析出试验，研究了氯析出过程中的几个因素(燃烧温度、停留时间、燃烧气氛、烟气中水蒸气含量)对反应的影响，确定了木屑反应的动力学方程式。得出如下结论：燃烧过程中Cl-HCl的转化率随燃烧温度的升高而显著增加；随停留时间的增加，HCl的析出存在两个明显的析出峰，这就清楚地说明至少有两种以上形式的氯存在于木屑中。氧化性气氛对氯化物生成影响不大，随炉内气氛由弱还原性气氛向强还原性气氛的转化，氯析出率明显降低；水蒸气的存在明显加速垃圾中氯的析出。木屑燃烧过程中，氯析出反应为零阶反应。     

单光子电离质谱用于二噁英前生体检测

垃圾焚烧处理是二噁英的主要产生源之一,在二噁英的形成阶段会先形成氯苯、氯酚、多环芳烃等二噁英类前生体。这些前生体浓度较高,并且与二噁英类毒性当量存在密切关联。对前生体的在线检测研究已成为主要研究方向之一。本研究利用自制的纳秒真空紫外电离-飞行时间质谱仪,发展了一种快速测量气相条件下氯苯、多氯酚、萘等方法,并通过标准样测试对该方法进行了实验评估。对于氯苯标准样,在5~100μg/L范围内,用本方法获得的母体离子信号强度与浓度呈现良好的线性关系。     

4氯化铜对聚氯乙烯燃烧产物的催化作用

用现代色谱分析技术确定了在不同炉温条件下,掺杂有CuCl~2的聚氯乙烯燃烧过程中二噁英和多环芳烃的生成量,研究了氯化铜用量对其生成量的影响。结果表? 鞯ゴ康木勐纫蚁┤忌詹罅康亩嗷贩继蜕倭康亩f英,氯化铜的加入可大大增加二噁英的生成量,并能抑制多环芳烃的产生。金属氯化物可能是促使聚氯乙? ┤忌詹f英的主要因素之一。     

4氯化铜对聚氯乙烯燃烧产物的催化作用

用现代色谱分析技术确定了在不同炉温条件下,掺杂有CuCl~2的聚氯乙烯燃烧过程中二噁英和多环芳烃的生成量,研究了氯化铜用量对其生成量的影响。结果表? 鞯ゴ康木勐纫蚁┤忌詹罅康亩嗷贩继蜕倭康亩f英,氯化铜的加入可大大增加二噁英的生成量,并能抑制多环芳烃的产生。金属氯化物可能是促使聚氯乙? ┤忌詹f英的主要因素之一。     

钴掺杂氮化硼纳米管吸附氯酚类污染物的理论研究

氯酚(CPs)类污染物是形成持久性有机污染物二噁英的先驱物, 具有较强的致畸、致癌和致突变性. 为探索去除或检测这类污染物的新型材料, 应用密度泛函理论研究了(8,0)单壁氮化硼纳米管(BNNT)和Co掺杂的(8,0)单壁氮化硼纳米管(Co-BNNT)对2-氯酚(2-CP)、2,4,6-三氯酚(TCP)、五氯酚(PCP)的吸附行为及作用机制. 结果表明, 与BNNT相比, Co-BNNT费米能级附近出现杂化态, 带隙明显减小. BNNT对2-CP、TCP和PCP呈现物理吸附, 而Co-BNNT对三种氯酚则是化学吸附, 纳米管与分子间发生了明显的电荷转移, 体系态密度在费米能级附近发生了明显变化. Co原子掺杂明显增强了BNNT的电子输运能力, 提高了纳米管对氯酚的吸附活性. Co-BNNT有望是去除或检测氯酚类污染物的潜在资源.     

二苯酮与氯代酚光化夺氢反应量子产率的测定

用自行研究制的脉冲激光光声微量量热计准确测定了二苯酮与５种氯代苯酚光化夺氢反应的量子产率,探讨了取代基对夺氢反应量子产率的影响。结果表明,随着氯代酚中氯原子数目的增多,空间位阻增大,致使发生夺氢反应后生成的自由基较难复合,从而提高了夺氢反应的量子产率。该法为人们从能量学的角度深入了解光化夺氢的机理提供了重要信息。     

基于热重红外联用分析的PE、PS、PVC热解机理研究

利用TGA-FTIR联用技术考察了PE、PS、PVC三种典型塑料的热解特性。结果表明,热稳定性从弱到强依次为PVC、PS、PE。PE热解反应过程为典型的一段式反应,红外光谱分析结果表明,PE热解过程为无规则断链形式,生成产物成分复杂,且随热解过程而改变,开始以饱和烃基团为主,中后期以烯烃基团为主,同时有少量炔烃;PS热解过程同样为一段式反应,红外光谱显示主要热解产物为苯乙烯单体,说明热解过程主要是苯乙烯的解聚过程;PVC热解过程较为复杂,主要分为脱氯阶段和共轭多烯重构阶段,红外光谱结果表明,产物中有芳香族化合物。脱氯过程和共轭多烯重构、环化过程在时间和空间上有重合,给二噁英类污染物的生成制造了可能。     

Formation of polychlorinated dibenzodioxins and dibenzofurans by heating chlorophenols and chlorophenates at various temperatures

Summary Polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are formed by pyrolysis of chlorophenols and chlorophenates. Under certain conditions the PCDD pattern is completely governed by the chlorine substitution of the starting molecules. Pyrolyses of chlorophenols at elevated temperatures, however, lead to complex PCDD/PCDF mixtures. Nearly all trito heptachlorodibenzodioxin and -dibenzofuran congeners can arise simultaneously from a mixture of only two trichlorophenols. In this case the substitution pattern of the products is no longer influenced by that of the chlorophenols used.

---

Bildung von polychlorierten Dibenzodioxinen und Dibenzofuranen durch Erhitzen von Chlorphenolen und Chlorphenolaten bei verschiedenen Temperaturen

Zusammenfassung Polychlorierte Dibenzodioxine (PCDD) und polychlorierte Dibenzofurane (PCDF) werden durch Pyrolyse von Chlorphenolen und Chlorphenolaten gebildet, wobei unter bestimmten Bedingungen das PCDD-Muster vollständig von der Chlorsubstitution der Ausgangsmoleküle bestimmt wird. Die Pyrolyse von Chlorphenolen bei höheren Temperaturen führt jedoch zu komplexen PCDD/ PCDF-Gemischen. Fast alle Tribis Heptachlordibenzodioxine und -dibenzofurane können gleichzeitig aus einer Mischung von nur zwei Trichlorphenolen hervorgehen. In diesem Fall wird das Substitutionsmuster der Produkte nicht mehr von dem der eingesetzten Chlorphenole beeinflußt.

     

加速溶剂萃取-硅胶柱净化-碱性氧化铝柱分离-气相色谱三重四极杆质谱法测定土壤中的二噁英类化合物

建立了加速溶剂萃取(ASE),酸性硅胶柱、复合硅胶柱及碱性氧化铝柱纯化分离,气相色谱-三重四极杆质谱测定土壤中二噁英/呋喃(PCDD/Fs)、多氯联苯(PCBs)、多氯萘(PCNs)的分析方法.选用正己烷-二氯甲烷(50∶50, V/V)作为ASE的提取溶剂,设定提取温度为120℃,加标回收实验表明本方法可行.用100 mL正己烷-二氯甲烷(95∶5, V/V)及50 mL正己烷-二氯甲烷(50∶50, V/V)依次淋洗碱性氧化铝柱,得到组分A(PCBs及PCNs)与组分B(PCDD/Fs),实现了PCDD/Fs与另外两种化合物的分离,排除了同系物间及其它杂质的干扰.使用同位素稀释-气相色谱三重四极杆质谱法(GC-MS/MS), 在选择反应监测(Selected reaction monitoring, SRM)模式下测定PCDD/Fs、PCBs和PCNs,3种化合物的仪器检出限(LOD)范围分别为0.04~0.25 μg/L, 0.10~0.20 μg/L和0.01~0.05 μg/L,目标物平均相对响应因子(RRF)的相对标准偏差(RSD)均小于13%.基质土加标实验中,3种化合物13C标记的同位素内标回收率的范围分别为50%~95%,51%~103%, 49%~74%.实际样品的分析结果表明,PCDD/Fs、PCBs及PCNs在土壤样品中的总含量范围分别为16.1~1148 pg/g、6.6~152.6 pg/g及10.9~99.5 pg/g,且样品测定结果与高分辨质谱测定结果相吻合.     

Sensitive and selective analysis of polychlorinated dibenzo-p-dioxins/dibenzofurans and their precursors by supersonic jet/resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry.

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), some of which are extremely toxic, are present at low concentrations in incinerator flue gases. The on-line real-time measurement of these compounds is necessary, since these concentrations fluctuate drastically with the process conditions used. Supersonic jet/resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry (SSJ/REMPI/TOF-MS), which provides both high selectivity and sensitivity, appears suitable for application to the on-line real-time monitoring of PCDD/Fs. In this review, the resonant ionization wavelengths of PCDD/Fs and their precursors are given. Moreover, improvements in SSJ/REMPI/TOF-MS that lead to enhanced sensitivity and selectivity are presented. That is, novel ionization sources and advanced ionization schemes are reported for the sensitive measurement of PCDD/Fs and their precursors. Those techniques are advantageous for the trace analysis of these compounds.     

Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in mountainous and park soils in Beijing,China

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analysed in 95 mountainous and park soil samples collected from 19 sites in Beijing, China. The levels of PCDD/Fs in the mountainous soils were low (0.086–0.59; mean 0.29; median 0.23 ng I-TEQ/kg). The levels in the park soils far from the city centre were a little higher (0.39–0.88, mean0.68; median 0.75 ng I-TEQ/kg). However, in the park soils near to the city centre, there were an abrupt jump in their concentration (1.7–3.2; mean 2.3, median 1.7 ng I-TEQ/kg), about ten times higher than those in the mountainous sites. Comparison of PCDD/Fs homologues and congener compositions between possible sources and samples indicated that the mountainous and park soils in Beijing had been slightly contaminated mainly by sodium pentachlorophenate, sewage sludge, atmospheric deposition and vehicle exhaust. These results have also been supported by the principal component analysis.     

同位素稀释高分辨气相色谱-高分辨质谱法测定土壤样品中二恶英类化合物的等价毒性当量不确定度的评定

采用同位素稀释高分辨气相色谱-高分辨质谱法（isotope dilution high resolution gas chromatography and high resolution mass spectrometry,ID-HRGC-HRMS）测定土壤样品中二恶英类化合物（polychlorinated dibenzo-p-dioxins and dibenzofurans,PCDD/Fs）的等价毒性当量（toxic equivalent quantity,TEQ）。讨论并确定了测定土壤样品中二恶英类化合物2,3,7,8位异构体不确定度的来源并合成了各异构体的相对标准不确定度;在此基础上,计算了3种等价毒性当量因子（toxic equivalent factor,TEF）框架下土壤样品中PCDD/Fs的TEQ浓度及其合成不确定度和扩展不确定度。     

Quantum chemical investigation of formation of polychlorodibenzo-p-dioxins and dibenzofurans from oxidation and pyrolysis of 2-chlorophenol

Density functional theory (DFT) calculations have been used to obtain thermochemical parameters for formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) from the oxidation of 2-chlorophenol. Formation mechanisms of PCDD through radical-radical coupling have been investigated in detail. The sequence of 2-chlorophenoxy radical coupling has been studied. The formation of chlorinated bis keto dimers which results from cross coupling of 2-chlorophenoxy at the ortho carbon bearing hydrogen (a known direct route for PCDF formation) passes through a tight transition structure whose barrier is 9.4 kcal/mol (0 K). Three routes for the formation of the most abundant PCDD/PCDF species (viz., 4,6-dichlorodibenzofuran, 4,6-DCDF, and 1-monochlorodibenzo-p-dioxin, 1-MCDD) in oxidation and pyrolysis of 2-chlorophenol are discussed. In the case of 4,6-DCDF, formation through H or HO + keto-keto <==> H2 or H2O + keto-keto* <==> H2 or H2O + enol-keto* <==> H2 or H2O + 4,6-DCDF + HO is shown to be the preferred route. The other two routes proceed via closed shell processes (keto-keto <==> enol-keto <==> enol-enol <==> H2O + 4,6-DCDF) and (keto-keto <==> enol-keto <==> (H-,OH-) 4,6-DCDF <==> H2O + 4,6-DCDF). Results indicate that 1-MCDD should be the favored product in 2-chlorophenol pyrolysis in agreement with experimental findings. According to our results, tautomerization (inter-ring hydrogen transfer) and intra-annular displacement of HCl would not be competitive with paths deriving from H abstraction from the phenolic oxygen and the benzene ring followed by displacement of Cl in the formation of dibenzo-p-dioxin (DD) and 1-MCDD. The results presented here will assist in construction of detailed kinetic models to account for the formation of PCDD/PCDF from chlorophenols.     

Unveiling the secondary pollution in the catalytic elimination of chlorinated organics: The formation of dioxins

Since the discovery of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) in the process of municipal solid waste incineration(MSWI),a large number of researches have been conducted to reveal their formation mechanisms and emission characteristics.As one of national priority control pollutants,chlorinated organics are inclined to transfer into PCDD/Fs in the heterogeneously catalyzed process,which has been considered to be one of great challenges in environmental catalysis.However,so far direct evidences to support such a conversion process are insufficient,and the reaction mechanisms are lack of exploration.This study investigated the catalytic elimination of chlorobenzene(CBz) over a range of industrially applied active species including Pt,Ru,V,Ce and Mn oxides,and explored their reaction byproducts,chlorine adsorption/desorption behaviors and PCDD/F formations.We found that all of these species could generate the PCDD/Fs,amongst which,Mn species were the most active for PCDD/F formation.Approximately 140 ng I-TEQg-1 PCDD/Fs were detected on the Mn-CNT surface after ageing at250℃ for 30 h.Even using the dichloromethane(DCM) as a precursor,significant PCDD/Fs were still detected.The Ru and V species were shown to generate much less polychlorinated byproducts and PCDD/Fs,owning to their sufficiently high abilities in Cl desorption,which were through the semi-Deacon and Br(?)nsted H reactions,respectively.     

模化城市生活垃圾衍生燃料制备及热解特性的研究

为保证城市固体废弃物（MSW）或垃圾衍生燃料（RDF）研究过程中所用样品的典型性和可重复性,首先根据我国城市生活垃圾的典型组成人工配制了垃圾衍生燃料（aRDF）,分析了aRDF的组成,采用热重 傅立叶变换红外光谱(TG-FTIR)联用技术研究了aRDF的热解特性,并采用差减微商法计算了热解动力学参数。结果表明,aRDF体现了我国MSW构成的主要特点,且与实际焚烧等过程的垃圾原料更为接近;aRDF在低温热解过程中,氯的释放与芳族化合物的产生处于不同的温度区间,并且缓慢的升温速度加大了HCl和芳族化合物释放的温度区间差异。这为避免高温下HCl对设备的腐蚀、减少甚至消除PCDD/Fs的形成提供了可能。aRDF的热解反应为一级反应,其活化能在64.6 kJ/mol～136kJ/mol的范围内变化。