有机物性质对混凝-微滤-纳滤去除水中重金属的影响

为了探明有机物性质对混凝-微滤-纳滤去除水中重金属的影响,将腐殖酸和乙酸分别作为背景有机物,系统考察了组合工艺对镉(Cd)、铜(Cu)、镍(Ni)和锌(Zn)的去除效能及其膜通量变化过程,并通过物料衡算对4种重金属的去除行为进行了比较分析。结果表明,当原水中不含有机物时,Cu的截留率最高,达到97%以上,纳滤膜是去除其他3种重金属的主要步骤。随着原水中腐殖酸含量的增大,混凝-微滤阶段对重金属的截留能力显著增强,膜通量衰减速度加快。相反地,乙酸的存在对于组合工艺处理效能具有明显的负面效应。此时,重金属既不能被铝盐絮体有效吸附,也不能通过静电作用截留在NF膜表面。4种重金属在滤液和浓水中的回收率Rrec都超过了80%,膜通量的变化与处理无机重金属溶液时相近。     

利用强化混凝去除水源水中天然有机物的研究进展

总结了近年来利用强化混凝去除水源水中天然有机物的研究,重点讨论了其作用机理和主要影响因素.水源水中天然有机物的含量和成分会因水源地和时间的不同而存在差异,对水源水中天然有机物的了解是保证强化混凝效果的基本前提.不同混凝条件下,强化混凝的主导作用机理不同.铁盐混凝剂、较低pH值、较高混凝剂投量和阳离子有利于提高强化混凝的效果.     

Analysis of accumulation, extractability, and metabolization of five different phenylarsenic compounds in plants by ion chromatography with mass spectrometric detection and by atomic emission spectroscopy

Phenylated arsenic compounds occur as highly toxic contaminants in former military areas where they were formed as degradation products of chemical warfare agents. Some phenylarsenic compounds such as roxarsone and aminophenylarsonic acids were applied as food additive and veterinary drugs in stock-breeding and therefore pose an environmental risk in agricultural used sites. Very few data exist in the literature concerning uptake and effects of phenylarsenic compounds in plants growing on contaminated soils. In this study, the accumulation, extractability, and metabolization of five different phenylarsenic compounds, phenylarsonic acid, p- and o-aminophenylarsonic acid, phenylarsine oxide, and 3-nitro-4-hydroxyphenylarsonic acid called roxarsone, by the terrestrial plant Tropaeolum majus were investigated. Ion chromatography coupled to inductively coupled plasma mass spectrometry was used to differentiate these arsenic compounds, and inductively coupled plasma atomic emission spectroscopy was used for total arsenic quantification. All compounds considered were taken up by the roots and transferred to stalks, leaves, and flowers. The strongest accumulation was observed for unsubstituted phenylarsonic acid followed by its trivalent analogue phenylarsine oxide that was mostly oxidized in soil whereas the amino- or nitro- and hydroxy-substituted phenylarsonic acids were accumulated to a smaller degree.The highest extraction yield of 90% for ground leaf material was achieved by 0.1 M phosphate buffer, pH 7.7, in a two-step extraction with a total extraction time of 24 h. The extraction of higher amounts of arsenic (50–70% of total arsenic present in leaves depending on arsenic species application) from non-ground intact leaves with deionized water in comparison with the buffer (20–40% of total arsenic) is ascribed to osmotic effects. The arsenic species analysis revealed a cleavage of the amino groups from the phenyl ring for plants treated with aminophenylarsonic acids. A further important metabolic effect consisted in the production of inorganic arsenate and arsenite from the phenylated arsonic acid groups.     

ORS-ICP-MS测定工业污泥中的重金属元素

建立了八极杆碰撞/反应池电感耦合等离子体质谱(ORS-ICP-MS)法测定工业污泥中Cr、Ni、As、Cd、Sb、Sn、Hg和Pb等8种重金属元素的分析方法。应用ORS技术消除了多原子离子对待测元素产生的质谱干扰,通过研究He碰撞气流速的变化对Cr、Ni、As和Sb预估检测限(EDL)的影响情况确定了最佳碰撞气流速,采用Rh为内标元素校正了质谱分析中基体效应并补偿了信号漂移。方法对工业污泥样品的检出限为13.5~34.3 ng/L,加标回收率在93.0%~107.6%之间,相对标准偏差(RSD)为1.5%~2.8%。     

Complexation parameters of heavy metals by olive mill wastewater determined by a cation exchange resin

Abstract

Complexing parameters in aqueous systems containing heavy metals and wastewater from olive‐oil mill (WOM) have been estimated using a cation exchange resin method. The parameters estimated were the maximum complexing ability (MCA), the stability constant (Kc) and a parameter indicating the stoichiometrical characteristics of the complex (a).

MCA of WOM for Cu, Zn, Pb and Mn was 0.470, 0.314, 0.068 and 0.300 mmol (g WOM)^‐1 respectively, and was related with the ionic radii of the various metal ions. The log Kc values followed the sequence: Cu>Pb>Zn>Mn in agreement with their respective electronegativities. In the case of Cu and Pb, data obtained here was compared with that determined in other work.     

热碱-EDTA耦合法强化污泥破解及效果分析

采用热碱-EDTA耦合法进一步提升热碱法破解污泥的效果,以期减少碱量和热能的消耗。选用影响污泥破解效果的pH、温度和EDTA投加量等因素设计L₁₆(4⁵)的正交实验,在得出最佳污泥破解条件下,对比考察了热碱法和热碱-EDTA耦合法破解污泥的效果。结果表明,热碱-EDTA耦合法相比热碱破解法,破解后SCOD、TN、TP、多糖和蛋白质溶出量分别提高了14.7%、5.6%、9.9%、3.6%和25.9%,污泥残渣中VS的含量(21.93%)也小于热碱破解法(29.68%),破解液中分子质量小于400 Da的小分子物质占比(40.68%)大于热碱破解的对应结果(32.34%)。通过污泥粒径测定和SEM观察发现,热碱-EDTA耦合法破解的污泥粒径分布峰值响应小于热碱破解,污泥固体分散性优于热碱破解。通过分析可知,热碱-EDTA耦合法可以提高中低温条件下热碱破解的有机物溶出率和有机物水解性能,降低污泥残渣中VS的相对含量,热碱-EDTA耦合法相比热碱法强化了污泥的破解效果。     

Bottom-up approach for the reaction of xenobiotics and their metabolites with model substances for natural organic matter by electrochemistry-mass spectrometry (EC-MS)

Risk assessment of xenobiotics requires a comprehensive understanding of their transformation in the environment. As most of the transformation processes usually involve a redox reaction or a hydrolysis as the first steps of the transformation, we applied an approach that uses an electrochemical cell to investigate model “redox” reactions in aqueous solutions for environmental processes. We investigated the degradation of a variety of xenobiotics from polar to nonpolar and analyzed their degradation products by on-line coupling of electrochemistry with mass spectrometry (EC-MS). Furthermore, we evaluated possible binding reactions with regard to the generation of non-extractable residues with some model substances (catechol, phthalic acid, γ-l-Glutamyl-l-cysteinyl-glycine (GSH) and l-histidine) deduced from a natural organic matter (NOM) structure model and identified possible binding-sites.Whereas typically investigations in soil/water-systems have been applied, we used to our knowledge for the first time a bottom-up approach, starting from the chemicals of interest and different model substances for natural organic matter to evaluate chemical binding mechanisms (or processes) in the EC-MS under redox conditions. Under oxidative conditions, bindings of the xenobiotics with catechol, GSH and histidine were found, but no reactions with the model compound phthalic acid were observed. In general, no chemical binding has yet been found under reductive conditions. In some cases (i.e. benzo[a]anthracene) the oxidation product only underwent a binding reaction, whereas the xenobiotic itself did not undergo any reactions.EC-MS is a promising fast and simple screening method to investigate the environmental behavior of xenobiotics and to evaluate the potential risks of newly synthesized substances.     

Simultaneous extraction of Cr(VI) and Cu(II) from humic acid with new synthesized EDTA derivatives

Soil washing is one of the few permanent treatment alternatives for removing metal contaminants. Ethylenediaminetetraacetic acid and its salts (EDTA) is very effective at removing cationic metals and has been utilized globally. However it is ineffective for anionic metal contaminants or metals bound to soil organic matter. The simultaneous removal of cationic and anionic metal contaminants by soil washing is difficult due to differences in their properties. The present study evaluated the potential of a washing process using two synthesized EDTA-derivatives, C₆HEDTA (2,2′-((2-((carboxymethyl)(2-(hexanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic acid) and C₁₂HEDTA (2,2′-((2-((carboxymethyl) (2-(dodecanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic acid), which consist of a hydrophilic polycarboxylic moiety and a hydrophobic moiety with a monoalkyl ester group. A series of equilibrium batch experiments at room temperature were conducted to investigate the efficacy of C₆HEDTA and C₁₂HEDTA as extractants for both oxyanion Cr(VI) and cationic Cu(II). Results showed that either C₆HEDTA or C₁₂HEDTA can extract both Cr(VI) and Cu(II) from humic acid simultaneously. However, C₆HEDTA was less effective for Cr(VI) probably because it has no surface activities to increase solubility of humic acid, like C₁₂HEDTA. Extraction of Cr(VI) was mainly attributed to the decreased surface tension and enhanced solubility of organic matter. Extraction of Cu(II) was attributed to both the Cu(II) chelation and enhanced solubility of humic acid. It was demonstrated that the hydrophilic polycarboxylic moiety of C₁₂HEDTA chelates cations while the monoalkyl ester group produces surface active properties that enhance the solubility of humic acid.     

EDTA及其回收溶液治理重金属污染土壤的研究

试验结果表明,EDTA能够有效地萃取土壤重金属,由于其价格较贵和不易被降解等特点,限制了它的广泛运用.在运用MINTEQA2模型对萃取液中重金属离子形态分析的基础上,选用Na2S沉淀法将重金属从EDTA萃取液中有效分离.同时将回收的EDTA连续进行萃取土壤重金属,由于回收EDTA浓度下降的原因,其效果比新鲜EDTA的要稍微差一点,但从经济和效率上来说,仍旧可以用来治理重金属污染的土壤.     

铁-铝盐混凝剂混合投加工艺控制溶解性残余铝的机理

铁-铝盐混凝剂混合投加是一种常用给水处理工艺。但由于缺乏有效表征手段,对上述工艺的内在机制认识不清。采用紫外-可见光谱法与非理想竞争吸附模型(NICA)相结合的方法,定量表征铁-铝盐凝剂混合投加时水体中溶解性有机物(DOM)特性。结果表明,铁盐(FeCl₃)投加能在保证水处理效能的情况下,显著提高酚基类官能团的去除效率,并且通过竞争络合位点抑制络合态有机铝的生成量,使溶解性残余铝浓度显著降低。以上研究结果对优化混凝工艺控制具有指导意义。     

荷负电超滤膜同时去除水中天然有机物和铅离子

通过特定的化学反应对截留分子量为30 kD的再生纤维素(RC)超滤膜进行改性,得到荷负电超滤膜,并研究了其表面荷电性能。选用腐殖酸作为天然有机物的代表物质,研究荷负电改性膜同时去除溶液中腐殖酸和铅离子,主要考察了pH值和腐殖酸铅离子络合作用对两者截留率的影响,并对比了荷负电膜和未改性膜去除天然有机物和铅离子的研究结果。得到如下结论:(1)在酸性及中性溶液环境下,随着pH值的升高,荷负电超滤膜对腐殖酸和铅离子的截留率都提高。(2)铅离子与腐殖酸共存时,腐殖酸铅离子络合体的荷负电性相比于原腐殖酸分子降低,荷负电超滤膜对混合溶液中腐殖酸的截留率有一定程度降低,络合在腐殖酸表面的铅离子随着腐殖酸的截留而被截留,铅离子截留率得到一定程度提升。(3)由于腐殖酸与铅离子络合体带负电,其与荷负电膜之间存在静电作用,所以荷负电改性膜对腐殖酸和铅离子的截留率比未改性中性膜高。     

天然溶解性有机质对黑炭吸附萘和菲的抑制作用

研究了土壤天然溶解性有机质(富里酸或腐殖酸)对黑炭吸附萘和菲的影响.结果表明:增加天然溶解性有机质的负载量能够减弱黑炭对萘和菲的吸附能力;而同在100mg的负载量条件下,不同分子量的富里酸或腐殖酸的负载对黑炭吸附萘和菲的抑制作用没有明显差别;相对于富里酸或腐殖酸单独负载,金属离子(Al3+或Fe3+)和富里酸或腐殖酸联...     

离子交换法改性的NaY分子筛对吸附含硫VOCs的性能提升

为解决分子筛在含湿条件下对小分子含硫VOCs吸附性能差的问题,并实现高效捕集,采用液相离子交换法选取不同金属离子 (Ag、Cu、Mg、Zn、Ce、Ca等) 对NaY和USY-3分子筛进行改性,以二甲基硫醚 (DMS) 作为模型物,考察2种改性分子筛对高湿度含硫VOCs脱除效果,进而优选性能优异的改性分子筛,再通过多组分VOCs竞争吸附实验来模拟实际应用效果。结果表明,NaY和USY-3分子筛改性后均可保持结构稳定,NaY型分子筛较USY-3分子筛具有更高的离子交换容量,改性后吸附性能提升更明显,CuY、AgY分子筛的DMS吸附性能优异 (CuY的穿透吸附量为203 mg·g⁻¹,AgY的穿透吸附量为132 mg·g⁻¹) 。然而,仅有Ag离子交换可提高NaY分子筛的抗水性,在1.5%水蒸气存在时,DMS穿透吸附量最高可达99 mg·g⁻¹,且5次循环再生后吸附容量仍在90%。在对二甲苯 (PX) 存在时,分子筛对2种VOCs的吸附量均高于80 mg·g⁻¹,且DMS具有绝对的竞争吸附优势。本研究表明AgY分子筛具有优异的抗水性和吸附选择性,可为其在含湿条件下对VOCs中小分子硫化物的吸附净化应用提供参考。     

Nitrate and natural organic matter in aqueous solutions irradiated by simulated sunlight

By means of simulated sunlight, the influence of natural organic matter (NOM) on the photochemical degradation of halogenated pesticides in the absence and presence of nitrate as a precursor of the highly reactive OH radicals in aqueous solutions and freshwater was investigated. Solutions of dichlorprop or terbutylazine (a) in phosphate-buffered demineralized water containing nitrate and/or NOM and (b) in natural freshwaters were irradiated by a 1000-W Xe short-arc lamp. The collimated beam was filtered using a combination of optical filters (WG 320 and WG 295) to simulate the solar spectrum under summer midday conditions. In the absence of nitrate and NOM, the pesticides were degraded photolytically by simulated sunlight. The degradation rates depended on the absorption spectrum in the UVB range and the quantum yield of the degradation. The photochemical degradation of the pesticides was faster in the presence of nitrate due to the sunlight-induced formation of OH radicals. In the absence of nitrate, low concentrations of NOM of a brownwater lake accelerated the degradation due to the formation of reactive species by NOM. At higher concentrations of NOM, the inner filter effect of NOM lowered the degradation rates. In the presence of 50 mg l−1 nitrate, NOM decreased the degradation rate significantly. In case the natural water samples were used as a matrix for the experiments (nitrate concentrations between 2 mg l−1 and 15 mg l−1, DOC concentrations below 2.3 mg l−1), NOM acted mainly as a radiation filter and as a scavenger of OH radicals. As a consequence, in most freshwater systems, the accelerating effect of NOM by the formation of reactive species is of minor importance compared to the inner filter effect and to radical scavenging.     

Fenton法降解垃圾渗滤液中的溶解性有机质

垃圾渗滤液是一种高浓度难降解废水,含有大量有毒物质和溶解性有机质（dissolved organic matter, DOM）,可生化性差。Fenton试剂（Fe2++H2O2）能产生活性极强的羟基自由基（·OH）,能快速氧化渗滤液中DOM和微量有机物质。本研究采用Fenton法处理垃圾渗滤液,结果表明,在优化的处理条件下,渗滤液COD和TOC去除率分别为65%和42%,其中混凝作用去除的COD和TOC分别为20%和21%。进一步通过紫外可见光谱扫描、SUVA254、E3/E4等指标评价,发现Fenton法可以有效降低渗滤液中的DOM含量,大分子有机物的含量明显减少,而分子量小的有机物含量相对增加,反应体系中溶解性有机物分子量随着反应的进行而降低,腐殖化程度降低。利用GC-MS定性出渗滤液原液中47种有机物,该类有机物在Fenton反应后上清液中未再检出,但5种物质（邻苯二甲酸二（2-乙基己）酯、植酮、角鲨烯、麥角甾烷醇和二氢胆固醇）在沉淀的铁泥中检出。研究发现不同pH值、H2O2和Fe2+浓度条件下,残留的COD与DOM、TOC和UV254存在显著的相关关系（R2> 0.9）。本研究结果为改进垃圾渗滤液处理工艺和探索DOM在Fenton过程中的降解行为提供科学依据。     

无机离子及天然有机物对纤维负载Fe0还原溴酸盐的影响

为了考察水中存在的NO3-、PO43-、SO42-、HCO3-和Cl-几种阴离子及天然有机物腐殖酸HA对纤维负载Fe0还原溴酸盐的影响,实验以接枝丙烯酸(AA)的聚丙烯(PP)纤维为载体,采用配位技术和液相还原法制备出了纤维负载Fe0(PP-g-AA-Fe0)材料,对纤维负载Fe0还原溴酸盐的反应效能进行了研究。结果表明,NO3-存在会与BrO3-产生竞争使还原反应速率有所降低,但这种竞争没有影响BrO3-完全被还原去除;PO43-、SO42-和HA存在对BrO3-还原反应影响不大,表观反应速率常数较单纯BrO3-还原体系略有增加,未出现文献报道中所说的明显抑制现象;HCO3-、Cl-的存在明显促进了纤维负载Fe0对BrO3-的还原。     

SCR脱硝尿素中微量元素的质谱法测定

建立了电感耦合等离子体质谱(ICP-MS)法测定SCR脱硝尿素中Na、Mg、Al、P、K、Ca、Cr、Fe、Ni、Cu、Zn、Pb等12种微量元素的分析方法.通过向碰撞/反应池(CRC)系统中引入氦气消除多原子离子质谱干扰,采用混合内标元素45Sc、89Y、209Bi消除基体效应.结果表明,各元素在一定范围内线性关系良好,方法的检出限为0.2~23.6 ng/L,样品的加标回收率在89.6%~108.4%之间,RSD在1.6%~3.8%之间.方法能准确测定SCR脱硝尿素中的多个微量元素,可用于SCR脱硝尿素的质量控制和安全评价.     

天然有机物共存时生物活性炭对17β-雌二醇的去除

以17β-雌二醇（E2）为目标物,研究了在天然有机物共存的情况下,生物活性炭（BAC）小柱和粒状活性炭（GAC）小柱去除E2的效果。结果表明,BAC小柱和GAC小柱都可有效去除E2,运行600d后出水仍未检出E2。从纵向浓度分布来看,BAC小柱对E2的处理效果略好于GAC小柱。BAC小柱去除E2主要是通过活性炭吸附作用和生物降解作用。空床接触时间也会对E2的去除产生影响。在BAC小柱和GAC小柱中,NOM的去除率随时间延长而降低,E2的去除率始终保持在100％,由此可以推断E2和NOM在活性炭的不同位置进行吸附。     

白洋淀沉水植物腐解溶解性有机物与重金属的相互作用

针对白洋淀秋冬季节水生植物腐解释放大量溶解性有机物(DOM)的问题,利用紫外可见光谱(UV-Vis)和激发发射光谱(EEMs)结合平行因子分析法(PARAFAC)对DOM样品进行表征和分离。实验结果表明,PARAFAC共分离出4种组分(C1、C2、C3和C4),类腐殖酸组分C1和C2、类蛋白组分C3、含有类蛋白组分和类富里酸组分共同组成的C4。此外,对样品进行荧光淬灭滴定实验来研究DOM与重金属(Cu (Ⅱ)和Cd (Ⅱ))的相互作用,发现Cu (Ⅱ)对所有组分都存在明显的淬灭效果,并可以较好地拟合出络合常数(lgK),而Cd (Ⅱ)只与C4有较好的络合效果,这是由于C4中的类富里酸成分所造成的。研究进一步发现,样品U2中类蛋白组分C3和C4对重金属的淬灭效果比样品U0的类蛋白组分明显。这是由于样品U2中所添加的植物量较多,而植物腐解所释放的主要成分为类蛋白物质,有助于增强类蛋白组分的络合能力。研究结果可为科学评价水生植物腐解释放DOM对水体中重金属的迁移转化提供依据。     

南方某水源水中天然有机物的特点及氯胺对氯化消毒副产物的控制

在对天然有机物分类的基础上进行了水体中有机物的特性研究,并采用氯胺对不同特性有机物的氯化消毒副产物进行了控制研究。结果表明,疏水酸占有机物总量的24%,疏水中性物质占41%,疏水性有机物占67%;对于三卤甲烷类消毒副产物生成势,疏水酸所产生的最多,疏水碱次之,亲水酸最少;对于卤乙酸类消毒副产物生成势,疏水碱产生的三卤乙酸最多,其次为疏水酸,亲水酸最少。氯胺对不同类有机物氯化消毒副产物控制程度不同,氯胺对疏水中性物质控制三卤甲烷类消毒副产物最好,其次是疏水碱和亲水碱;对疏水酸的三卤甲烷生成量控制较弱,对亲水酸的控制效果最差;氯胺对亲水碱氯化产生卤乙酸的控制效果最好,其次是疏水碱,控制效果最差的为疏水中性物质。