湿热环境对PMMA混杂纳米复合材料性能的影响

目的研究湿热环境对聚甲基丙烯酸甲酯(PMMA)混杂纳米复合材料性能的影响。方法利用制备的水包油型杂化乳液稳定剂EMI/GO/CNTs稳定以甲基丙烯酸甲酯(MMA)为油相的水包油型Pickering乳液,用偶氮二异丁氰(AIBN)为引发剂,引发Pickering乳液进行悬浮聚合,聚合产物为PMMA混杂纳米复合材料。将PMMA混杂纳米复合材料模压成型,分别在室温及50℃下进行水浸吸湿实验。采用光学显微镜对Pickering乳液液滴形貌进行分析,通过复合材料的质量变化、动态力学分析测试、导电性测试,对复合材料的吸湿率、玻璃化转变温度及导电性变化进行分析。结果用EMI/GO/CNTs稳定的以MMA为油相的水包油型Pickering乳液具有良好的稳定性,乳液液滴的尺寸分布范围较窄,分布较均匀。复合材料的吸水量随时间增加逐渐增大,达到吸湿平衡状态后,吸湿率基本不变。不同温度下水浸复合材料的吸湿速度和平衡吸湿率不同,50℃水浸比25℃水浸的复合材料的吸湿速度快且平衡吸湿率大。湿热后复合材料的玻璃化转变温度基本不变。复合材料经湿热环境处理后电导率升高1~2个数量级。结论利用制备的杂化乳液稳定剂制备出Pickering乳液并进行悬浮聚合、模压成型,制备出PMMA复合材料。经水浸湿热处理后的复合材料,其吸湿率和电导率均有一定变化,玻璃化转变温度基本不变。     

TiO2纳米管对水源水中MC-LR的光催化降解

采用“草酸+氟化铵”水相电解液体系通过阳极氧化法制备出了TiO₂纳米管材料,可有效光催化深度降解水源水中的微囊藻毒素（MC-LR）.结果表明,阳极氧化电压为20V、组分配比为1/12mol/L H₂C₂O₄·2H₂O+0.5wt% NH₄F、电解液pH值为4、阳极氧化时间1~2h的条件下制得的纳米管形貌最清晰,孔径为50nm左右,管长为250~600nm;催化剂经过500~600℃的温度煅烧后对MC-LR的光催化降解效率相对较高;pH值在3.5或8左右时,有利于MC-LR的光催化降解,且光化学反应符合准一级反应动力学模型;MC-LR的光催化降解机理主要包括产生的强氧化性·OH自由基对Adda支链共轭双键、Mdha氨基酸单双键以及Adda支链中甲氧基等部位的攻击氧化和肽键的水解.     

Kinetic adsorption of application of carbon nanotubes for Pb(Ⅱ) removal from aqueous solution

The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(Ⅱ) reached maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coeffcients from Langmuir isotherm model indicates the strong adsorptions of Pb(Ⅱ) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). The results indicates tha...     

腐殖酸对水中多壁碳纳米管凝聚特性的影响

以多壁碳纳米管(MWNTs)稳定悬浮液为对象,研究了腐殖酸(HA)对水中MWNTs凝聚特性的影响.结果表明,采用SDS超声分散法制备的MWNTs稳定悬浮液具有较强的稳定性,投加电解质可通过压缩双电层机制使其发生凝聚,并符合经典的DLVO理论.HA存在时,可通过增大MWNTs颗粒间的空间位阻效应和亲水性,抑制凝聚反应发生,从而提高其在水中的稳定性.Ca2+可与HA发生络合桥联作用,导致MWNTs颗粒粒径的大幅提高,强化凝聚发生.水中MWNTs的分散和凝聚性质将受到有机物性质和电解质种类等复杂因素的影响.     

氨基化碳纳米管/石墨烯气凝胶对甲醛吸附研究

针对目前室内空气污染物甲醛超标的现象,将新型碳纳米材料(石墨烯、碳纳米管)引入到气体污染物去除领域.利用石墨烯水溶液在一定条件下形成凝胶的特性,采用海绵作为骨架,构造石墨烯/碳纳米管/海绵三维气凝胶结构,并进一步采用氨基修饰提高该氨基化碳纳米管/石墨烯气凝胶(GCNTs/EDA-S)对室内空气污染物甲醛的吸附性能,研究石墨烯与碳纳米管(CNTs)对气态甲醛吸附作用机理.样品吸附实验结果对比分析表明,石墨烯和碳纳米管氨基官能团修饰后对气态甲醛均有良好的吸附性能,其中GCNTs/EDA-S在甲醛浓度为3.7ppm时,吸附实验的穿透时间可达到4024min/g,最大吸附容量为13.5mg/g.     

Catalytic wet air oxidation of phenol,nitrobenzene and aniline over the multi-walled carbon nanotubes (MWCNTs) as catalysts

Wet air oxidation (WAO) is one of effective technologies to eliminate hazardous, toxic and highly concentrated organic compounds in the wastewater. In the paper, multi-walled carbon nanotubes (MWCNTs), functionalized by O₃, were used as catalysts in the absence of any metals to investigate the catalytic activity in the catalytic wet air oxidation (CWAO) of phenol, nitrobenzene (NB) and aniline at the mild operating conditions (reaction temperature of 155°C and total pressure of 2.5 MPa) in a batch reactor. The MWCNTs were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), gas adsorption measurements (BET), fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The functionalized MWCNTs showed good catalytic performance. In the CWAO of phenol over the functionalized MWCNTs, total phenol removal was obtained after 90 min run, and the reaction apparent activation energy was ca. 40 kJ·mol^-1. The NB was not removed in the CWAO of single NB, while ca. 97% NB removal was obtained and 40% NB removal was attributed to the catalytic activity after 180 min run in the presence of phenol. Ca. 49% aniline conversion was achieved after 120 min run in the CWAO of aniline.     

Interaction of carbonaceous nanomaterials with wastewater biomass

Increasing production and use of carbonaceous nanomaterials (NMs) will increase their release to the sewer system and to municipal wastewater treatment plants. There is little quantitative knowledge on the removal of multi-walled carbon nanotubes (MWCNTs), graphene oxide (GO), or few-layer graphene (FLG) from wastewater into the wastewater biomass. As such, we investigated the quantification of GO and MWCNTs by UV-Vis spectrophotometry, and FLG using programmable thermal analysis (PTA), respectively. We further explored the removal of pristine and oxidized MWCNTs (O-MWCNTs), GO, and FLG in a biomass suspension. At least 96% of pristine and O-MWCNTs were removed from the water phase through aggregation and 30-min settling in presence or absence of biomass with an initial MWCNT concentration of 25 mg·L⁻¹. Only 65% of GO was removed with biomass concentration at or above 1,000 mg·L⁻¹ as total suspended solids (TSS) with the initial GO concentration of 25 mg·L⁻¹. As UV-Vis spectrophotometry does not work well on quantification of FLG, we studied the removal of FLG at a lower biomass concentration (50 mg TSS·L⁻¹) using PTA, which showed a 16% removal of FLG with an initial concentration of 1 mg·L⁻¹. The removal data for GO and FLG were fitted using the Freundlich equation (R² = 0.55, 0.94, respectively). The data presented in this study for carbonaceous NM removal from wastewater provides quantitative information for environmental exposure modeling and life cycle assessment.     

典型碳纳米材料在水中的凝聚特性比较

以富勒烯(C₆₀)和多壁碳纳米管(MWNTs)纳米颗粒悬浮液为对象,采用动态光散射技术对比研究了电解质、有机物等环境因素对其在水中凝聚和稳定性的影响.结果表明,电解质存在下,可通过压缩双电层作用使水中碳纳米材料发生凝聚反应,凝聚过程均符合经典的胶体稳定性(DLVO)理论;MWNTs较C₆₀稳定性弱、更易凝聚;两种纳米颗粒悬浮液对应的Na⁺、Mg²⁺ 和Ca²⁺的临界凝聚浓度均远高于其在天然水体中的含量.Na⁺和Mg²⁺凝聚体系中,腐殖酸(HA)可通过空间位阻作用抑制凝聚发生,且对C₆₀的抑制作用更强.HA可与Ca²⁺发生络合,强化纳米颗粒凝聚反应,并对MWNTs具有更强的强化凝聚作用.不同碳纳米材料和环境因子存在着不同的相互作用关系,将影响其在水中的稳定性.     

新型吸附搅拌棒被动采样器研制及应用——基于多壁碳纳米管的改性

结合传统被动采样器原理和新发展的吸附搅拌棒技术,研制了以多壁碳纳米管-聚二甲基硅氧烷(MWCTNs/PDMS)作为涂层的新型吸附搅拌棒被动采样器,并以苯酚(PhOH)、己烯雌酚(DES)和铅(Pb)作为目标污染物,考察被动采样器其吸附性能,优化其吸附条件.结果表明,与商业化PDMS涂层吸附搅拌棒被动采样器相比,含MWCTNs/PDMS涂层吸附搅拌棒被动采样器能更快达到吸附平衡时间、具有更大的饱和吸附容量.甲醇是PhOH和DES优良解吸剂,0.6mol/L HNO₃为Pb最优解吸剂.该新型被动采样器重复使用50次以上其解吸效率仍能达到70%以上,具有良好的稳定性和重复利用效果.     

多壁碳纳米管对水稻幼苗的植物毒性研究

考察了浓度为10、50和100 mg·L~(-1)的多壁碳纳米管(MWCNTs)的植物毒性,通过测量水稻生长指数、根系氧化应激反应、细胞膜损伤和生理功能的变化,探索了其具体的毒性机制。将水稻幼苗暴露于不同浓度的MWCNTs悬浮液中培养10 d后,高浓度处理组(100 mg·L~(-1))中水稻幼苗地上部分和根系鲜重分别降低至对照组的87.6%±1.1%和69.2%±7.8%。对根系深入研究发现氧化应激反应和细胞膜的损伤主要出现在高浓度处理组,此时过氧化氢酶(CAT)活性由对照组的(8.8±1.6)U·mg-1prot(protein,蛋白质)增加至(16.3±2.8)U·mg-1prot,丙二醛(MDA)含量由对照组的(8.0±0.3)μmol·g-1FW(fresh weight,鲜重)增加至(15.1±1.4)μmol·g-1FW。然而,水稻根系的生化酶活性在低浓度(10 mg·L~(-1))时就开始明显降低。通过透射电镜(TEM)观察发现,MWCNTs颗粒分布在水稻幼苗根系细胞内,从而证实了MWCNTs能被植物细胞吸收。