Inhibitory effects of nisin-coated multi-walled carbon nanotube sheet on biofilm formation from Bacillus anthracis spores

Multi-walled carbon nanotube（MWCNT） sheet was fabricated from a drawable MWCNT forest and then deposited on poly（methyl methacrylate） film. The film was further coated with a natural antimicrobial peptide nisin. We studied the effects of nisin coating on the attachment of Bacillus anthracis spores, the germination of attached spores, and the subsequent biofilm formation from attached spores. It was found that the strong adsorptivity and the super hydrophobicity of MWCNTs provided an ideal platform for nisin coating. Nisin coating on MWCNT sheets decreased surface hydrophobicity, reduced spore attachment, and reduced the germination of attached spores by 3.5 fold, and further inhibited the subsequent biofilm formation by 94.6% compared to that on uncoated MWCNT sheet. Nisin also changed the morphology of vegetative cells in the formed biofilm.The results of this study demonstrated that the anti-adhesion and antimicrobial effect of nisin in combination with the physical properties of carbon nanotubes had the potential in producing effective anti-biofilm formation surfaces.     

Acid-assisted hydrothermal synthesis of nanocrystalline TiO2 from titanate nanotubes: Influence of acids on the photodegradation of gaseous toluene

In order to efficiently remove volatile organic compounds (VOCs) from indoor air, onedimensional titanate nanotubes (TiNTs) were hydrothermally treated to prepare TiO₂ nanocrystals with different crystalline phases, shapes and sizes. The influences of various acids such as CH₃COOH, HNO₃, HCl, HF and H₂SO₄ used in the treatment were separately compared to optimize the performance of the TiO₂ nanocrystals. Comparedwith the strong and corrosive inorganic acids, CH₃COOH was not only safer andmore environmentally friendly, but also more efficient in promoting the photocatalytic activity of the obtained TiO₂. Itwasobserved that the anatase TiO₂ synthesized in 15 mol/L CH₃COOH solution exhibited the highest photodegradation rate of gaseous toluene (94%), exceeding that of P25 (44%) by a factor ofmore than two. The improved photocatalytic activity was attributed to the small crystallite size and surface modification by CH₃COOH. The influence of relative humidity (20%-80%) on the performance of TiO₂ nanocrystals was also studied. The anatase TiO₂ synthesized in 15 mol/L CH₃COOH solution was more tolerant tomoisture than the other TiO₂ nanocrystals and P25.     

全氟辛烷磺酸(PFOS)和多壁碳纳米管(MWCNTs)复合对斑马鱼外周血红细胞DNA的损伤

为了评价全氟辛烷磺酸(PFOS)和多壁碳纳米管(MWCNTs)对水环境及鱼类的影响,以斑马鱼为模式生物,研究了PFOS和MWCNTs复合对斑马鱼外周血红细胞的DNA损伤。将成年斑马鱼暴露于PFOS(0.2、0.4、0.8、1.6 mg·L-1)、MWCNTs(50 mg·L-1)、PFOS+MWCNTs(0.2+50、0.4+50、0.8+50、1.6+50 mg·L-1)和对照溶液中30 d后,断尾取血进行微核试验和彗星试验。结果表明:PFOS和MWCNTs均可造成斑马鱼外周血红细胞的DNA损伤。1.6 mg·L-1PFOS处理组的微核率、Olive尾矩及尾长分别为(36.3±0.25)‰、(87.91±14.90)μm和(250.49±34.71)μm。PFOS与MWCNTs复合后,斑马鱼外周血红细胞的DNA损伤效应明显降低。复合处理组斑马鱼外周血红细胞的微核率、Olive尾矩及尾长均低于PFOS单独处理相。1.6 mg·L-1复合处理组的微核率、Olive尾矩及尾长比PFOS单独处理组分别降低了24.7%、68.9%、52.4%。因此,在实验浓度范围内,MWCNTs可以降低PFOS对斑马鱼外周血红细胞的DNA损伤。     

单壁碳纳米管材料对水稻幼苗的毒性效应

随着碳纳米管材料(CNTs)被广泛地应用于工业和商业等多个领域,其将不可避免地进入到大气、水和土壤环境中,从而对生态系统结构和功能产生一些负面影响.为明确进入水环境中的碳纳米管材料对农业生产的潜在危险,本实验采用水培法,研究了不同浓度(10、20、40mg·L~(-1))的单壁碳纳米管材料(SWCNTs)对萌发期内水稻的发芽率、根长耐性指数和幼苗生长期内水稻的鲜重、叶绿素和可溶性蛋白的影响,以及单壁碳纳米管材料在水稻根部的累积.结果表明,在萌发期,胁迫处理4 d后,与对照相比,10、20、40 mg·L-1SWCNTs处理组对水稻发芽率没有任何抑制作用,但会延迟种子的发芽时间;水稻根长耐性指数随着单壁碳纳米管材料浓度的增加而下降.在幼苗生长期,胁迫处理30 d后,与对照相比,水稻鲜重随着单壁碳纳米管材料浓度的增加而分别下降14.2%、21.0%和38.8%;与此相类似,水稻叶绿素和可溶性蛋白质含量随着单壁碳纳米管材料浓度的增加而下降;另外,通过透射电镜观察(TEM)发现,SWCNTs颗粒分布在水稻幼苗根尖表皮细胞的细胞壁中.SWCNTs对水稻生长起抑制作用,且随着浓度的增加抑制作用逐渐增强.     

Enhanced U(VI) bioreduction by alginate-immobilized uranium-reducing bacteria in the presence of carbon nanotubes and anthraquinone-2,6-disulfonate

Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2, 6-disulfonate (AQDS), and carbon nanotubes (CNTs). The effects of different AQDS-CNTs contents, U(IV) concentrations, and metal ions on U(IV) reduction by immobilized beads were examined. Over 97.5% U(VI) (20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(VI) occurred at initial U(VI) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(III), Cu(II) and Mn(II) slightly increased U(VI) reduction, whereas Cr(VI), Ni(II), Pb(II), and Zn(II) significantly inhibited U(VI) reduction. After eight successive incubation-washing cycles or 8 hr of retention time (HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters.     

Insights into the electron transfer mechanisms of permanganate activation by carbon nanotube membrane for enhanced micropollutants degradation

● A CNT filter enabled effective KMnO₄ activation via facilitated electron transfer. ● Ultra-fast degradation of micropollutants were achieved in KMnO₄/CNT system. ● CNT mediated electron transfer process from electron-rich molecules to KMnO₄. ● Electron transfer dominated organic degradation. Numerous reagents have been proposed as electron sacrificers to induce the decomposition of permanganate (KMnO₄) by producing highly reactive Mn species for micropollutants degradation. However, this strategy can lead to low KMnO₄ utilization efficiency due to limitations associated with poor mass transport and high energy consumption. In the present study, we rationally designed a catalytic carbon nanotube (CNT) membrane for KMnO₄ activation toward enhanced degradation of micropollutants. The proposed flow-through system outperformed conventional batch reactor owing to the improved mass transfer via convection. Under optimal conditionals, a > 70% removal (equivalent to an oxidation flux of 2.43 mmol/(h·m²)) of 80 μmol/L sulfamethoxazole (SMX) solution can be achieved at single-pass mode. The experimental analysis and DFT studies verified that CNT could mediate direct electron transfer from organic molecules to KMnO₄, resulting in a high utilization efficiency of KMnO₄. Furthermore, the KMnO₄/CNT system had outstanding reusability and CNT could maintain a long-lasting reactivity, which served as a green strategy for the remediation of micropollutants in a sustainable manner. This study provides new insights into the electron transfer mechanisms and unveils the advantages of effective KMnO₄ utilization in the KMnO₄/CNT system for environmental remediation.     

Zn-TiO_2纳米管的光催化活性

采用水热合成-浸渍法制备锌掺杂TiO2纳米管（Zn-TiO2纳米管）,透射电镜照片显示Zn-TiO2纳米管为两端开口形貌均一的中空管状结构,管径约6～8 nm,壁厚约1 nm,长度约50～200 nm。研究了Zn-TiO2纳米管对甲基橙的光催化性能,结果表明：掺杂适量锌提高了TiO2纳米管对甲基橙的光催化降解性能,0.4%Zn-TiO2纳米管的光催化性能最佳。同时还探讨了Zn-TiO2纳米管用量和初始pH值等因素对光催化降解甲基橙的影响,结果显示Zn-TiO2纳米管能有效地降解甲基橙。随着光催化反应进行,CODCr去除率和脱色率变化规律不完全相同,可能是由于芳基和烷基降解速率不同所致。     

复合纳米微粒修饰碳糊电极方波伏安法检测水中甲基对硫磷

采用溶胶-凝胶法合成纳米ZrO2,将其混合在石墨粉和碳纳米管（CNTs）中,利用硅油做粘合剂,制得一次性有机磷农药（OPs）检测碳糊电极（CNTs/ZrO2│CPE）,并对水中甲基对硫磷（MP）进行了检测.采用扫描电镜（SEM）、X射线荧光光谱（XRFS）表征电极的制备过程,采用循环伏安（CV）法和方波伏安（SWV）法...     

复合光催化剂(TiO2/多壁碳纳米管)制备工艺条件对甲基橙光催化降解动力学的影响

采用溶胶-凝胶法在不同条件下制备了多壁碳纳米管(MwCNTs)负载纳米TiO2的复合光催化剂(TiO2/MWCNTs).以偶氮类染料甲基橙为模拟污染物,研究不同制备工艺参数的复合光催化剂对甲基橙的光催化降解动力学的影响.对TiO2/MWCNTs的表征结果表明,纳米TiO2较好地分散在多壁碳纳米管表面;随着温度的升高,复...     

巯基硅烷改性多壁碳纳米管的合成及其对Cd2+的吸附性能研究

利用3-巯丙基三甲氧基硅烷(MPTMS)作硅烷偶联剂对多壁碳纳米管(MWCNTs)进行改性,制备巯基硅烷改性多壁碳纳米管(SHMWCNTs),并进行了SH-MWCNTs对Cd~(2+)的批量吸附实验.同时,利用扫描电镜(SEM)、X射线光子能量仪(EDS)、红外光谱(FT-IR)对SHMWCNTs进行表征,探究了溶液初始pH、吸附剂投加量、吸附时间、溶液初始Cd~(2+)浓度等因素对吸附效果的影响,分析了吸附动力学特征及吸附等温线特征,初步探讨了吸附机理.SEM、EDS与FT-IR图谱显示,MPTMS已成功接枝到MWCNTs表面,表明SH-MWCNTs制备成功.吸附时间为90 min,pH为4时的吸附效果最佳,吸附量随SH-MWCNTs投加量、Cd~(2+)浓度的增加而增大.吸附动力学和吸附等温线研究表明,SHMWCNTs对Cd~(2+)的吸附动力学符合准二级线性方程,吸附等温线符合Freundlich、Langmuir 2种模型,吸附以单分子层吸附为主,也存在层间扩散的多层吸附.