胺丙基硅的微结构和表面特性在其对两种微囊藻毒素吸附中的作用

考察了粒状胺丙基硅(CUNAX00X)对水溶液中微囊藻毒素-LR(mLR)和微囊藻毒素-LA(mLA)的等温吸附行为,并通过对胺丙基硅结构中的微孔尺寸分布特征、表面官能团--胺丙基团(-CH2CH2CH2NH 3)和羟基自由基(·OH)的红外分析,对吸附机制进行了初步探讨.结果表明,胺丙基硅通过物理吸附和化学吸附对水溶液中的mLR和mLA进行吸附,即胺丙基硅结构中的有效吸附微孔对mLR/mLA的物理吸附,固体表面离子化的胺丙基团和·OH与mLR/mLA分子结构中离子化的羧基(-COO-)以及pH=4.33条件下mLR分子结构中离子化的胍基(-NHCNH·NH 2)之间的弱离子吸附.     

活性炭纤维对水中微囊藻毒素的吸附性能

利用活性炭纤维对水中微囊藻毒素MC—LR的吸附,研究了吸附过程的热力学与动力学特性。结果表明,活性炭纤维对MC—LR的平衡吸附量在相同温度下随MC-LR初始浓度的增加而显著增大,并随着温度升高而增加,最大吸附量达246μg／g。不同温度条件下,活性炭纤维对MC-LR的吸附均较好地符合Langmuir等温吸附模型。通过热力学分析发现,△H=15．7kJ／mol、△G〈0、△S〉0,表明该吸附是自发的、吸热的过程,温度升高有利于吸附反应。动力学研究表明,该过程符合一级动力学方程。吸附反应速率受颗粒内扩散和液膜扩散共同影响。活性炭纤维经再生后,平衡吸附量变化较小,具有良好的重复使用性能。     

碳源对铜绿微囊藻生理特性及微囊藻毒素产率的影响

为研究水体中不同碳源对铜绿微囊藻生理特性的影响,以Na2CO3与葡萄糖分别作为铜绿微囊藻生长的无机碳源与有机碳源,将铜绿微囊藻于光照下进行培养,并对其一系列的生理特性与微囊藻毒素产率进行检测。实验结果表明,同等碳浓度下,有机碳源更能促进铜绿微囊藻的生长,经过30 d的培养,铜绿微囊藻在有机碳源中的产量为187.55 g,比其在无机碳源中的产量提高了6.06%;微囊藻毒素在有机碳源中的产量为969.00μg/g,而在无机碳源中的产量却升高至1 193.60μg/g。参与藻毒素合成的3种氨基酸在无机碳源中的浓度要比有机碳源中的浓度高,但是其余几种氨基酸的含量与之情况相反。而有机碳源培养的铜绿微囊藻总可溶性蛋白含量为387.00μg/g,比无机碳源培养的铜绿微囊藻的蛋白含量提高了93.60%。     

微囊藻毒素测定中产生的干扰及排除

采用固相萃取-高效液相色谱法定性、定量测定水中微囊藻毒素,对水样富集管(观赏鱼用氧气塑料管、橡胶管、医用乳胶管和硅胶管)、塑料材质(聚丙烯离心管等)、针式过滤器(水系、有机系针式过滤器)产生的干扰和吸附现象进行了深入探索.结果表明,观赏鱼用氧气塑料管对微囊藻毒索测定会产生严重的正干扰,在流动相甲醇:磷酸盐缓冲溶液(体积比)为50:50时,干扰得以排除;聚丙烯离心管在微囊藻毒素投加量较低时,对微囊藻毒索吸附率较高,造成回收率偏低;不同的针式过滤器对溶解在不同体积分数的甲醇溶液中的微囊藻毒素有明显不同的吸附能力.     

微囊藻毒素的产生及其影响因子

介绍了光照、温度、营养元素、pH值等环境因子对微囊藻的生长及其毒素生成的影响.一定强度的光照促进毒素的合成,微囊藻生长在较低的温度或营养元素受限制时,生长速率下降,但毒素产率较高.微囊藻毒素的含量在藻的指数生长后期与稳定期达最大值,毒素产率则在指数生长初期达最大.不同环境因子可能通过不同途径影响毒素的产生,需进一步研究藻毒素的功能及合成途径.     

滇池底泥微生物菌群对微囊藻毒素的生物降解

采用滇池水华蓝藻中提取提纯的微囊藻毒素（microcystins，MCs）作为微生物生长的碳源和氮源，从长期暴露于蓝藻水华的滇池底泥中，通过从含低浓度到高浓度MCs的逐步培养驯化，获得了高效降解MCs的微生物混合菌群，在初始MC-RR和LR浓度大约分别为50mg／L和30mg／L下，3d内可将MCs全部降解。进一步活性研究显示，不同含碳和含氮化合物虽然能够促进混合微生物菌群的生长，但对降解MCs却无明显的促进作用，说明MCs既可以作为微生物生长的碳源，又可以作为微生物生长的氮源，在富含有机物的天然水体中并不一定能够促进微生物对MCs的生物降解。     

铁锰改性铜绿微囊藻对锑的吸附性能

利用生物质吸附去除水中重金属离子具有制备简单、成本低廉、环境影响小等优点,通过高锰酸钾-硫酸亚铁处理过程对铜绿微囊藻改性,制备了能够高效吸附水中锑(Sb)的铁锰改性藻粉复合材料。扫描电镜和X射线光电子能谱分析表明,改性藻粉中存在大量铁锰氧化物颗粒,铁锰的主要存在形式为Fe₂O₃和MnO₂。改性后的复合藻粉对Sb(Ⅲ)的吸附量从3.06 mg·g^-1增加到35.30 mg·g^-1,对Sb(Ⅴ)的吸附量从3.07 mg·g^-1增加到4.37 mg·g^-1,并且改性后的复合藻粉到达吸附平衡的时间更短。Langmuir模型可以很好地描述Sb在复合藻粉上的吸附行为,Elovich模型对藻粉吸附Sb(Ⅲ)和Sb(Ⅴ)的吸附过程拟合较好(R²=0.957,0.943),而复合藻粉更适用准二级动力学模型(R²=0.953,0.961)。Sb(Ⅲ)主要通过氧化和吸附作用被去除,而Sb(Ⅴ)在复合藻粉表面形成表面络合物后被吸附。共存阴离子(SO₄^2-、CO₃^2-、PO₄^3-)的存在对复合藻粉吸附Sb(Ⅲ)几乎没有影响,但是共存阴离子浓度越高,对Sb(Ⅴ)的吸附抑制越明显。     

超声波有机改性凹凸棒土的苯酚吸附性能研究

采用超声波技术,对凹凸棒土进行有机改性,提高凹凸棒土的苯酚吸附能力,比较了不同的阳离子表面活性剂的改性效果,并且通过正交实验得出了超声波改性的最优化工艺条件为：十八烷基三甲基氯化铵的添加比例为35 mmol/100 g,超声波处理时间10 min,屏极电流0.5 A.在此条件下,苯酚去除率可达酸处理凹凸棒土的80倍以上,是搅拌有机改性的1.5倍.     

滇池底泥微生物菌群对微囊藻毒素的生物降解

采用滇池水华蓝藻中提取提纯的微囊藻毒素(microcystins,MCs)作为微生物生长的碳源和氮源,从长期暴露于蓝藻水华的滇池底泥中,通过从含低浓度到高浓度MCs的逐步培养驯化,获得了高效降解MCs的微生物混合菌群,在初始MC-RR和LR浓度大约分别为50 mg/L和30 mg/L下,3 d内可将MCs全部降解.进一步活性研究显示,不同含碳和含氮化合物虽然能够促进混合微生物菌群的生长,但对降解MCs却无明显的促进作用,说明MCs既可以作为微生物生长的碳源,又可以作为微生物生长的氮源,在富含有机物的天然水体中并不一定能够促进微生物对MCs的生物降解.     

活性炭表面酸性含氧官能团对吸附甲醛的影响

利用Bothem滴定法测定了化学浸渍处理的活性炭表面酸性含氧官能团浓度,研究表面酸性含氧官能团对甲醛吸附的效应。结果表明,HNO3浸渍处理能有效增大活性炭表面的羧基、酚羟基和内酯基浓度;H2O2浸渍处理主要增大了活性炭表面的酚羟基浓度;随着NaOH浓度的增大,活性炭表面的酚羟基、内酯基和羰基浓度大致呈先增大后减小的趋势,这是由于NaOH的化学清洗作用和酸碱中和反应所致;HNO3浸渍处理的活性炭表面的酸性含氧官能团浓度显著超过NaOH、H2O2浸渍处理的活性炭,而30%(质量分数)NaOH浸渍处理的活性炭和30%(体积分数)H2O2浸渍处理的活性炭吸附甲醛的饱和时间比HNO3浸渍处理的活性炭吸附甲醛最大饱和时间分别多4.0、1.5 h,说明酚羟基能够显著影响活性炭吸附甲醛的效果。     

水环境中微囊藻毒素检测技术研究进展

随着世界各国对微囊藻毒素的重视,中国也在相关水质标准里新增了微囊藻毒素这项指标.因此,水环境中微囊藻毒素的检测和控制变得非常重要,而检测更是控制的基础.比较详细地综述了目前国内外在微囊藻毒素检测方面的各种不同的研究方法和成果;并在总结这些研究的基础上,展望了微囊藻毒素检测的发展方向.     

微波加热对活性炭表面基团及其对SO2吸附性能的影响

采用了微波加热技术,通过在不同微波功率和辐射时间条件下对不同粒径活性炭进行改性,研究了改性前后活性炭的表面化学基团、元素组成的变化,以及对SO2吸附性能的影响.结果表明,经过微波改性后活性炭的SO2吸附性能大为提高,微波功率是影响改性活性炭脱硫性能的主要因素.活性炭经微波热处理后,酸性基团发生分解,表面含氧量减少,碱性特征增强,是吸附性能增加的主要原因之一.     

Effects of compositional heterogeneity and nanoporosity of raw and treated biomass-generated soot on adsorption and absorption of organic contaminants

A biomass-generated soot was sequentially treated by HCl-HF solution, organic solvent, and oxidative acid to remove ash, extractable native organic matter (EOM), and amorphous carbon. The compositional heterogeneity and nano-structure of the untreated and treated soot samples were characterized by elemental analysis, thermal gravimetric analysis, BET-N₂ surface area, and electron microscopic analysis. Sorption properties of polar and nonpolar organic pollutants onto the soot samples were compared, and individual contributions of adsorption and absorption were quantified. The sorption isotherms for raw sample were practically linear, while were nonlinear for the pretreated-soot. The removal of EOM enhanced adsorption and reduced absorption, indicating that EOM served as a partitioning phase and simultaneously masked the adsorptive sites. By drastic-oxidation, the outer amorphous carbon and the inner disordered core of the soot particles were completely removed, and a fullerene-like nanoporous structure (aromatic shell) was created, which promoted additional π-π interaction between phenanthrene and the soot.     

Enhancement of phenanthrene adsorption on a clayey soil and clay minerals by coexisting lead or cadmium

Phenanthrene is commonly present together with heavy metals at many contaminated sites. This study investigated the influence of coexisting lead (Pb²⁺) or cadmium (Cd²⁺) on phenanthrene adsorption on soils. Batch experiments were conducted under different geochemical conditions including pH, mineral structure, organic matter content, and varying amounts of heavy metals. The results showed that the presence of heavy metals in solution at a fixed pH of 5.8 ± 0.1 enhanced phenanthrene adsorption, the extent of which was closely related to the concentrations and the electro-negativity of the metals. The enhancement on phenanthrene adsorption was positively correlated to the amount of adsorbed metals. Although Cd²⁺ is a softer Lewis acid, Pb²⁺ displayed a more significant effect as it was adsorbed to a greater extent on the soil surfaces. Thus, density of cation accumulation appears to be more influential than metal softness in enhancing phenanthrene adsorption. Moreover, with a portion of organic matter removed by heating at 550 °C, there was a stronger enhancement of phenanthrene adsorption by coexisting Pb²⁺, indicating an increasingly dominant mechanisms associated with Pb²⁺ at a lower organic matter content. Similar enhancement phenomenon was observed on bentonite and kaolinite, probably resulting from the cation-π bonding between the adsorbed soft metal cations and the aromatic ring of phenanthrene in solution. The desorption experiments further suggested that the bonding of phenanthrene adsorption was strengthened in the presence of Pb²⁺ and that a larger proportion of adsorbed phenanthrene remained on the soils (residual fraction) even after sequential methanol extractions. Further spectroscopic analyses and surface characterization are required to provide direct evidence of the formation and relative significance of cation-π bond for phenanthrene adsorption.     

Effect of humic matter on metal adsorption onto clay materials: Testing the linear additive model

Migration of contaminants with low affinity for the aqueous phase is essentially governed by interaction with mobile carriers such as humic colloids. Their impact is, however, not sufficiently described by interaction constants alone since the humic carriers themselves are subject to a solid–liquid distribution that depends on geochemical parameters.In our study, co-adsorption of the REE terbium (as an analogue of trivalent actinides) and humic acid onto three clay materials (illite, montmorillonite, Opalinus clay) was investigated as a function of pH. ¹⁶⁰Tb(III) and ¹³¹I-labelled humic acid were employed as radiotracers, allowing experiments at very low concentrations to mimic probable conditions in the far-field of a nuclear waste repository. Humate complexation of Tb was examined by anion and cation exchange techniques, also considering competitive effects of metals leached from the clay materials.The results revealed that desorption of metals from clay barriers, occurring in consequence of acidification processes, is generally counteracted in the presence of humic matter. For all clay materials under study, adsorption of Tb was found to be enhanced in neutral and acidic systems with humic acid, which is explained by additional adsorption of humic-bound Tb.A commonly used composite approach (linear additive model) was tested for suitability in reconstructing the solid–liquid distribution of Tb in ternary systems (Tb/humic acid/clay) on the basis of data determined for binary subsystems. The model can qualitatively explain the influence of humic acid as a function of pH, but it failed to reproduce our experimental data quantitatively. It appears that the elementary processes (metal adsorption, metal–humate complexation, humic acid adsorption) cannot be considered to be independent of each other. Possible reasons are discussed.     

Estimation of surface area of montmorillonite by ethylene oxide chain adsorption

This study investigates the feasibility of using ethylene oxide chain adsorption to determine the surface area of an expandable clay, montmorillonite. Experimental results indicate that high molecular weight poly(ethylene oxide) or nonionic surfactant with long ethylene oxide chain should be used to provide reasonable estimations for monolayer capacity. The method has advantages over Brunauer, Emmett, and Teller method in that it is readily applicable to a wide range of areas, particularly to 2:1 layer silicates under aqueous conditions.     

铁和铝氧化物涂层砂的过滤与吸附性能评价

总结性地对3种不同氧化物涂层砂和未涂层砂的表面特性、过滤和吸附性能进行了比较与分析,明确了适用范围。改性滤料的高温加热和碱性沉积两种制备方法中,涂铁宜选前者,涂铝宜用后者。涂层砂的比表面积增大,吸附容量增加,使石英砂表面电荷的带电性质改变,有利于水中杂质的去除。涂铁砂适合于除氟和除砷及除有机物;涂铝砂适合于除浊、除有机物和除锌。     

六氯苯对水体微型生物群落的影响及其吸附行为

研究了六氯苯(HCB)对微型水生生物群落的影响及其吸附、传递过程.测定了群落的耗氧量和不同粒经颗粒物的生物量及HCB变化.试验结果显示,在6μg/L HCB影响下,群落的呼吸作用受到抑制,生物量减少.试验第1天,30.0%(质量分数,下同)的HCB以溶解态存在,26.3%吸附在0.22～2 μm的颗粒物(以细菌为主)上,22.1%吸附在2～8 μm的颗粒物(以鞭毛虫和藻类为主)上,21.6%吸附在大于8 μm的颗粒物(以藻类和大型原生动物为主)上.48 h后,溶解态的HCB逐渐减少,并由食物链低营养级向高营养级传递.最后74.9%的HCB都吸附在微型生物群落等颗粒物上,只有25.1%的HCB以溶解态存在.     

表面活性剂在北京碱性土壤中的吸附行为研究

通过静态吸附实验,研究了北京碱性土壤对阴离子表面活性剂SDS、阳离子表面活性剂CTAB和非离子表面活性剂Tween80的吸附行为,考察了温度对表面活性剂吸附的影响.结果表明:7种不同土样对SDS、CTAB和Tween80的吸附等温线均较好地符合Langmuir吸附模式,其吸附能力的大小顺序为2号轻壤土》轻粘土》中壤土》砂壤土》5号轻壤土》重壤土》紧砂土,这主要是由于7种土样的pH、有机质含量和机械组成不同的缘故;同一土壤中,CTAB的吸附量》Tween80的吸附量》SDS的吸附量;温度的升高,不利于SDS和CTAB在土壤中的吸附,而有利于Tween80的吸附.