碳基材料对污水厂尾水和太湖水体中CDOM的吸附特征

采用颗粒活性炭、粉末活性炭和碳纳米管3种典型碳基材料来吸附太湖水和污水厂尾水中的有机物,考察碳基材料对水中有色可溶性有机物(CDOM)的吸附特征。基于荧光光谱和平行因子分析(PARAFAC),提取出C1(腐殖酸类)、C2(色氨酸类蛋白)和C3(酪氨酸类蛋白)3个PARAFAC荧光组分。粉末活性炭和碳纳米管具有发达的中孔孔隙结构,对水中大分子有机物具有较高的吸附容量,颗粒活性炭微孔结构发达反而不利于吸附水中腐殖酸等大分子有机物。粉末活性炭对水中有机物具有最高的吸附速率,对太湖水中荧光组分C1、C2和C3 的吸附速率分别为0.278、0.358和0.359 min-1,颗粒活性炭的吸附速率明显低于粉末活性炭和碳纳米管。研究结果揭示了水中复杂混合有机物的吸附特征,为吸附工艺参数的优化提供技术参考。     

Influence of the initial state of carbon nanotubes on their colloidal stability under natural conditions

The colloidal stability of dry and suspended carbon nanotubes (CNTs) in the presence of amphiphilic compounds (i.e. natural organic matter or surfactants) at environmentally realistic concentrations was investigated over several days. The suspensions were analyzed for CNT concentration (UV-vis spectroscopy), particle size (nanoparticle tracking analysis), and CNT length and dispersion quality (TEM). When added in dry form, around 1% of the added CNTs remained suspended. Pre-dispersion in organic solvent or anionic detergent stabilized up to 65% of the added CNTs after 20 days of mild shaking and 5 days of settling. The initial state of the CNTs (dry vs. suspended) and the medium composition hence are critical determinants for the partitioning of CNTs between sediment and the water column. TEM analysis revealed that single suspended CNTs were present in all suspensions and that shaking and settling resulted in a fractionation of the CNTs with shorter CNTs remaining predominantly in suspension.     

碳纳米管基复合吸附剂的制备及其吸附性能

为了解决碳纳米管(CNTs)在吸附水中污染物时易聚集、难分离的问题,本文采用静电自组装技术将碳纳米管固定化在具有微米级粒径的碳酸钙颗粒表面,设计制备了壳-核结构的CNTs基复合吸附剂.实验考查了不同碳纳米管分散体系对复合吸附剂制备的影响,并采用Zeta电位、拉曼光谱、扫描电镜等手段对复合吸附剂的制备过程和结构进行表征,探讨了制备的碳纳米管基复合吸附剂对菲的吸附性能.结果发现,复合吸附剂对菲的吸附能力随CNTs载量的增加而增大,CNTs标化的吸附系数则随CNTs载量的增加而下降,碳纳米管是复合吸附剂的主要吸附位点.     

碳纳米管修饰电极对苯二酚3种异构体的研究

文章应用循环伏安法(CV)研究了邻苯二酚(CC)、对苯二酚(HQ)和间苯二酚(RS)在多壁碳纳米管修饰的玻碳电极(MWNTs/GCE)表面的电催化氧化行为,同时对pH、扫描速度、温度等试验条件的影响也进行了研究。结果表明:MWNTs/GCE电极对CC、HQ和RS均表现出较好的电催化和电分离作用;在高浓度HQ和RS存在条件下,CC的氧化峰电流在0.05～7.00mmol/L范围内与浓度呈良好的线性关系,相关系数R²=0.9989;修饰电极实现了对实际废水中苯二酚三种异构体的同时测定。     

Fe3+掺杂纳米管TiO2光催化臭氧化去除水中腐植酸

HA(humic acids, 腐植酸)是一种难降解天然有机物,常规饮用水处理工艺很难将其去除. 采用水热合成法制备纳米管TiO₂,并通过TEM(透射电镜)、XRD(X射线衍射)、XPS(X射线光电子能谱)和BET比表面积分析对催化剂进行表征,考察纳米管TiO₂光催化臭氧化对HA的去除效果. 结果表明:①254 nm紫外光照射下,500 ℃煅烧纳米管TiO₂催化臭氧化HA的工艺去除效果最佳,HA去除率可达42.1%,较单独臭氧化工艺提高92.2%. ②采用Fe³⁺掺杂纳米管TiO₂催化臭氧化工艺时,Fe³⁺掺杂量为1.0%(原子百分含量),煅烧温度为550 ℃时,催化效果最好,HA去除率可达79.5%. ③HA去除率高于TOC,0~10min内该现象更为明显. ④考察陶粒和活性炭负载Fe³⁺掺杂纳米管TiO₂的催化效果及催化次数对催化性能的影响发现,陶粒和活性炭负载Fe³⁺掺杂纳米管TiO₂存在下,HA去除率分别为85.1%和97.7%,使用4次后,HA去除率分别为73.9%和82.8%.     

BiOCl/MWCNTs复合催化剂对罗丹明B光催化降解研究

以B(iNO3)3.5H2O和NaCl为原料,多壁碳纳米管(MWCNTs)为载体,水解法合成碳纳米管负载氯氧化铋复合型光催化剂(BiOCl/MWCNTs)。通过TEM、XRD、UV-Vis对催化剂的微观形貌、主要成分和光学吸收进行了表征,并以500 W氙灯为可见光光源,研究了其对罗丹明B的光催化降解能力。TEM和XRD结果表明,复合催化剂中BiOCl成块状与MWCNTs结合,粒径小,分散好;UV-Vis则显示,BiOCl/MWCNTs对420⁷80 nm波长段的光的吸收强于BiOCl,有利于可见光催化。光照2.5 h后,BiOCl和BiOCl/MWCNTs对罗丹明B的降解率分别达到78%和96%。BiOCl/MWCNTs对罗丹明B光催化反应符合一级反应动力学特征,速率常数为1.23 h-1,相比BiOCl提高了98.2%。     

ZrxMg1-xO supported cobalt catalysts for methane decomposition into COx-free hydrogen and carbon nanotubes

Zirconia-magnesia supported cobalt catalysts with various Zr/Mg atomic ratios were prepared and evaluated for non-oxidative catalytic decomposition of methane to produce CO_x-free hydrogen and carbon nanotube. The catalytic performance of the catalysts was performed in a continuous fixed bed flow reactor at 700°C under atmospheric pressure. The fresh and spent catalysts were characterized by XRD, TPR, BET, TEM, and Raman spectroscopy. The results showed that the change in Zr/Mg ratio of the mixed oxide support has a significant effect on the catalytic performance of the active Co metal. The catalyst 30%Co/Zr_0.8Mg_0.2 showed the highest activity and stability within the used series of catalysts with hydrogen yield reached up to 79%. Both Co/Mg_1.0 and Co/Zr_1.0 showed poor stability due to strong Co-Mg interaction and aggregation of Co species on Zr support, respectively. All catalysts produced mainly MWCNTs with different diameters depending on the Zr/Mg ratio. The outer diameter increased with increasing Zr content in the catalyst due to the enlargement of the particle size of cobalt as a result of aggregation.     

Deposition of copper nanoparticles on multiwalled carbon nanotubes modified with poly (acrylic acid) and their antimicrobial application in water treatment

A novel hybrid material, Cu-PAA/MWCNTs (copper nanoparticles deposited multiwalled carbon nanotubes with poly (acrylic acid) as dispersant, was prepared and expected to obtain a more effective and well-dispersed disinfection material for water treatment. X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), the X-ray fluorescence (XRF), X-ray photoelectron spectra (XPS), Fourier transform infrared spectra (FT-IR), Raman spectroscopy, and thermal gravimetric analyzer (TGA) were used to characterize the Cu-PAA/MWCNTs. Escherichia coli (E. coil) was employed as the target bacteria. The cell viability determination and fluorescence imaging results demonstrated that Cu-PAA/MWCNTs possessed strong antimicrobial ability on E. coil. The deposited Cu was suggested to play an important role in the antimicrobial action of Cu-PAA/MWCNTs.     

碳纳米管活化过一硫酸盐降解金橙G过程及动力学

采用碳纳米管(CNT)作为固体活化剂,活化过一硫酸盐(PMS)氧化降解偶氮染料金橙G(OG).结果表明,CNT活化PMS降解OG的效果要比活性炭(GAC)好,45 min可使OG的脱色率达到99%;并研究了CNT活化PMS降解OG的机制及反应过程的动力学,发现CNT活化PMS产生的自由基主要是SO_4~-·,活化场所在CNT的表面.通过对CNT/PMS体系降解OG的主要影响因素(温度、OG初始浓度、CNT投加量、PMS浓度、初始pH)进行一级动力学拟合.最后通过紫外可见光谱分析,发现OG在479 nm和330 nm处吸收峰强度明显减少,表明OG分子中偶氮键及萘环结构均一定程度被破坏;且CNT/PMS降解体系对染料OG具有一定矿化率.     

人工纳米材料的生物效应及其对生态环境的影响

人工纳米材料由于具有独特的物理化学性质而得到广泛的应用,其对人体健康及环境的潜在影响也已引起科学界及政府部门的关注.通过总结近年来的相关研究资料,分类归纳了目前国内外对一些常见的人工纳米材料如富勒烯、碳纳米管、量子点、二氧化钛、纳米铁材料及纳米铝材料的生物和生态效应研究,详细总结了纳米材料毒理学的研究对象、研究方法以及最新研究成果,同时分析了各种纳米材料生物毒性的可能机制,最后对纳米材料安全性今后的研究方向进行了展望.