基于氢碘酸还原氧化石墨烯的研究

在石墨烯的多种制备方法中,我们选用氧化-还原法制备以保留石墨烯上的某些官能团,获得较高的电导率。我们采用改进Hummers法,以高锰酸钾与石墨粉质量比9∶1为原料,浓硫酸为溶剂更安全高效地制备氧化石墨烯(GO),避免高温氧化时大量破坏石墨的面内共轭结构。采用氢碘酸法、氢碘酸乙醇法、氢碘酸乙酸法三种途径来制备还原氧化石墨烯(r GO),比较发现氢碘酸乙酸还原法是温和高效的还原策略,即在一定量乙酸及55%的氢碘酸的混合液中,氧化石墨烯粉末在40℃下还原2d,其电导率达14600S/m,高于其它两法。通过改进氧化还原条件,制备了仅边缘修饰,面内共轭结构几乎无破坏的石墨烯。制备的r GO在邻二氯苯中能够很好地分散,其后用含溴修饰剂对其进行了边缘修饰,引入了可作为反应位点的溴原子。     

石墨烯/棉织物制备及其电热性能研究

采用丝网印刷方式将氧化石墨烯浆料印制在棉织物表面,再经还原方法得到了电热性能优良的石墨烯棉织物。综合分析织物表面形貌、表面电阻及发热性能,探究了印制次数、还原浓度、还原时间及还原剂种类对石墨烯棉织物发热性能影响。结果表明,印制次数为10次,还原浓度为5 mg/mL,时间6 h,施加在两端电压为24 V时,织物的表面电阻为4.0 kΩ/cm,表面温度为46.8℃,电热性能达到最佳。     

氧化石墨烯/聚苯胺(GO/PANI)纳米复合材料的制备及其对废水中Cr(Ⅵ)吸附性能测试

重金属离子在自然环境中难降解、易富集、毒性大,目前重金属污染已成为全球广泛关注的问题。吸附法在处理重金属废水中有着广泛的应用,本研究以石墨和苯胺为基本原料,成功制备出氧化石墨烯/聚苯胺复合材料,并且研究了氧化石墨烯/聚苯胺复合材料对六价铬的吸附性能,结果表明氧化石墨烯/聚苯胺复合材料对六价铬的吸附性能优于单一的氧化石墨烯和聚苯胺材料,该复合材料有较大的吸附潜力。     

胺功能化氧化石墨烯对水泥基复合材料性能的影响

氧化石墨烯（GO）在水泥浆料中的团聚会影响其对水泥复合材料的力学增强作用。为了解决氧化石墨烯在水泥浆料中的分散性问题,用三乙醇胺（TEOA）通过化学法对氧化石墨烯进行胺功能化（TEOA-GO）,并制备了氧化石墨烯水泥基复合材料（GO/C）和胺功能化氧化石墨烯水泥基复合材料（TEOA-GO/C）。分别采用X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶红外光谱（FT-IR）等手段对样品结构进行表征。结果表明：与氧化石墨烯相比,胺功能化氧化石墨烯在氢氧化钙溶液中的分散性更好;水泥基复合材料的力学性能测定结果显示,当掺杂0.03%（质量分数）的胺功能化氧化石墨烯时,水泥基复合材料28 d抗折强度最大为7.96 MPa,相较于空白样和氧化石墨烯水泥基复合材料分别提高了15.3%和5.43%;当掺杂0.05%（质量分数）胺功能化氧化石墨烯时,水泥基复合材料28 d抗压强度最大为74.14 MPa,相较于空白样和氧化石墨烯水泥基复合材料分别提高了40.68%和11.99%;扫描电镜表征结果进一步表明,加入胺功能化氧化石墨烯,有利于提高水泥的水化程度,阻碍裂缝的扩展,提高水泥的力学性能。     

氧化石墨烯水性粘结涂层性能研究

主要研究常温下氧化石墨烯(GO)水分散效果以及不同浓度GO对水性粘结涂层性能的影响。采用纳米粒度及Zeta电位分析仪、附着力测试仪和万能试验机进行测试及表征。结果表明,GO在去离子水、硼酸和碳酸氢钠三种分散液中的水分散性效果测试,得出去离子水的分散效果最好;GO掺量为0.2‰～0.3‰时,拉拔强度、拉伸强度以及断裂延伸率分别提高了85.6%,118%和65.8%。同时也验证了氧化石墨烯水性粘结涂层的低温柔韧性、高温稳定性、耐酸碱性以及抗渗透性等,均能满足使用要求。     

聚乙烯亚胺修饰的氧化石墨烯对Cr(Ⅵ)的吸附性能研究

将聚乙烯亚胺(PEI)接枝到氧化石墨烯(GO)表面,得到聚乙烯亚胺修饰的氧化石墨烯(GO-PEI)材料。通过FTIR、XRD、TGA对GO-PEI的结构及PEI接枝量进行表征,并研究其对水中Cr(Ⅵ)的吸附性能。结果表明,PEI成功接枝到GO表面,其氨基含量为13.72 mmol/g。GO-PEI对Cr(Ⅵ)表现出优良的吸附性能,其吸附过程符合Langmuir等温吸附模型和准二级动力学模型。GO-PEI对Cr(Ⅵ)的去除是吸附与化学还原共同作用的结果。     

水热体系中四氧化三铁与氧化石墨烯复合纳米颗粒的合成

在200℃自气压水热条件下制备了四氧化三铁与氧化石墨烯复合纳米颗粒。使用透射电子显微镜(TEM)、X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)等一系列仪器进行表征,结果表明四氧化三铁与氧化石墨烯复合纳米颗粒由粒径大约20 nm的四氧化三铁纳米颗粒与氧化石墨烯复合而成,数据分析表明氧化石墨烯对于四氧化三铁纳米颗粒的形成和进一步演化起到了一定的作用。     

氧化石墨烯负载金纳米颗粒及其催化活性研究

在不外加任何还原剂的情况下,利用氯金酸和氧化石墨烯之间的氧化还原反应将金纳米颗粒成功负载到氧化石墨烯上,合成了金纳米颗粒/氧化石墨烯复合材料。利用透射电镜(TEM)和X-射线衍射(XRD)对复合材料进行了结构表征与形态分析,并研究了金纳米颗粒/氧化石墨烯复合材料对Suzuki-Miyaura偶联反应的催化效果。结果表明,通过调节氯金酸与氧化石墨烯的质量比,可以得到不同形状的金纳米颗粒;金纳米颗粒/氧化石墨烯复合材料对Suzuki-Miyaura偶联反应具有很高的催化活性,并且很容易从反应体系中回收。     

聚合物基氧化石墨烯纳米复合材料研究进展

氧化石墨烯作为石墨烯的重要衍生物,原料来源广泛,制备过程简单,成本低廉,具有优异力学性能、耐磨性能以及吸附性能等,其还原产物具有优良的导电性能和导热性能等,是聚合物基纳米复合材料的理想填料。近年来,随着复合材料制备方法的不断革新,聚合物基氧化石墨烯纳米复合材料在储能、阻燃等领域实现了规模化应用,有助于引领聚合物基氧化石墨烯纳米复合材料相关产品的进一步开发和应用。该文系统介绍了氧化石墨烯的共价改性方法以及非共价改性方法,综述了聚合物基氧化石墨烯纳米复合材料的研究进展,展望了聚合物基氧化石墨烯纳米复合材料的发展前景。     

尼龙11/石墨烯氧化物纳米复合材料的动态流变性能

采用原位聚合法制备了尼龙11(Nylon 11,Polyamide 11)/石墨烯氧化物(GO)纳米复合材料,并利用旋转流变仪研究了纳米复合材料的流变行为。研究结果表明:尼龙11及其复合材料均为假塑性流体,呈现切力变稀的现象;GO的加入降低了尼龙11/GO纳米复合材料的储能模量、损耗模量和复数黏度;用Cole-Cole理论检测尼龙11/GO纳米复合材料,其曲线出现双峰,表明复合材料发生相分离,与Han曲线一致。     

Dependence of Graphene Oxide (GO) Toxicity on Oxidation Level,Elemental Composition,and Size

The mass production of graphene oxide (GO) unavoidably elevates the chance of human exposure, as well as the possibility of release into the environment with high stability, raising public concern as to its potential toxicological risks and the implications for humans and ecosystems. Therefore, a thorough assessment of GO toxicity, including its potential reliance on key physicochemical factors, which is lacking in the literature, is of high significance and importance. In this study, GO toxicity, and its dependence on oxidation level, elemental composition, and size, were comprehensively assessed. A newly established quantitative toxicogenomic-based toxicity testing approach, combined with conventional phenotypic bioassays, were employed. The toxicogenomic assay utilized a GFP-fused yeast reporter library covering key cellular toxicity pathways. The results reveal that, indeed, the elemental composition and size do exert impacts on GO toxicity, while the oxidation level exhibits no significant effects. The UV-treated GO, with significantly higher carbon-carbon groups and carboxyl groups, showed a higher toxicity level, especially in the protein and chemical stress categories. With the decrease in size, the toxicity level of the sonicated GOs tended to increase. It is proposed that the covering and subsequent internalization of GO sheets might be the main mode of action in yeast cells.     

Graphene Oxide (GO): A Promising Nanomaterial against Infectious Diseases Caused by Multidrug-Resistant Bacteria

Infectious diseases are major threat due to it being the main cause of enormous morbidity and mortality in the world. Multidrug-resistant (MDR) bacteria put an additional burden of infection leading to inferior treatment by the antibiotics of the latest generations. The emergence and spread of MDR bacteria (so-called “superbugs”), due to mutations in the bacteria and overuse of antibiotics, should be considered a serious concern. Recently, the rapid advancement of nanoscience and nanotechnology has produced several antimicrobial nanoparticles. It has been suggested that nanoparticles rely on very different mechanisms of antibacterial activity when compared to antibiotics. Graphene-based nanomaterials are fast emerging as “two-dimensional wonder materials” due to their unique structure and excellent mechanical, optical and electrical properties and have been exploited in electronics and other fields. Emerging trends show that their exceptional properties can be exploited for biomedical applications, especially in drug delivery and tissue engineering. Moreover, graphene derivatives were found to have in vitro antibacterial properties. In the recent years, there have been many studies demonstrating the antibacterial effects of GO on various types of bacteria. In this review article, we will be focusing on the aforementioned studies, focusing on the mechanisms, difference between the studies, limitations and future directions.     

Preparation and Characterization of Novel Poly(Urethane-Imide) Nanocomposite Based on Graphene,Graphene Oxide and Reduced Graphene Oxide

In this work in-situ preparation of novel poly(urethane-imide)/graphene, graphene oxide and reduced graphene oxide nanocomposite is reported by the reaction of 4,4´-diphenylmethane diisocyanate, polypropylene glycol, 3,3’,4,4′-benzophenone tetra carboxylic dianhydride and nanomaterials in the loadings levels of 0.5, 1.5, 2.5, and 3.5 pbw in propylene carbonate as an alternative green solvent. The synthesized poly(urethane-imide) nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹HNMR), thermogravimetric analysis (TGA), attenuated total reflection (ATR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The resulting nanocomposite showed enhanced thermal stability when compared with pristine and unfilled poly(urethane-imide) sample.     

Removal Mechanism of Natural Organic Matter and Organic Acid by Ozone in the Presence of Goethite

The oxidations of natural organic matter (NOM) and a model compound (p-chlorobenzoic acid) were characterized using ozonation and catalytic ozonation processes. In general, the catalytic ozonation showed better performance in the removal of organics tested in the study. The hydrophobic, transphilic, and hydrophilic NOM fractions were isolated using XAD-8 and -4 resins to evaluate the reaction characteristics. The catalytic ozonation in the presence of goethite accomplished the higher removal of NOM with simultaneous reduction of the three fractions than the ozonation which removed the hydrophobic portion only. The analysis of discrete size distributions of NOM revealed that ozonation yielded a removal of >1,000MW and an increase of <1,000MW, whereas all molecular weight fractions reduced after catalytic ozonation. The concentrations of model compound and aqueous and gaseous ozone were monitored during the oxidations, and efficiencies were compared for cases in the absence and presence of iron oxide (FeOOH).     

氧化石墨烯尺寸对水泥基复合材料的影响

采用Hummers法以石墨粉为原料制备氧化石墨烯(GO),采用球磨法制备不同尺寸的氧化石墨烯纳米片,分别使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)和马尔文激光粒度仪(Zetasizer Nano,Zs)进行结构表征.结果 表明,球磨法可制备不同粒径分布的氧化石墨烯纳米片;水泥基复合材料的SEM微观形貌以及力学性能测定结果显示当掺杂0.25％、球磨16 h制得的氧化石墨烯(80 ～ 184 nm),复合材料的抗折、抗压强度分别为12.1 MPa和73 MPa,相较于对照样品提高了47.56％和38.52％;小尺寸氧化石墨烯促进水泥内部形成规则有序的水化物,这些水化物在水泥内堆叠,形成相互交联的晶体网络,微观上改变复合材料内部结构,宏观上提高了其力学性能.     

Fast Removal of Sr(II) From Water by Graphene Oxide and Chitosan Modified Graphene Oxide

Graphene oxide is a unique material that can be used for adsorption of radioactive waste because it contains various function groups such as epoxide, carbonyl, carboxyl and hydroxyl in addition to its high specific surface area. The as-prepared GO and the modified one (GO-chitosan composite) have been prepared then characterized and used as adsorbent for radioactive metal ions [Strontium, Sr(II)]. The results showed that the prepared materials are efficient adsorbents for removal of Sr(II) from water. The effect of contact time, pH and temperature on adsorption have been studied. The results indicated that the maximum adsorption capacity was about 140 and 179.6 mg/g for GO and GO-chitosan composite respectively. It was found that pH?~?6 and temperature?~?40 °C are the best condition for removal of Sr(II) from water. Two isotherm models (Langmuir and Freundlich) and three kinetic models (Pseudo-first-order, pseudo-second-order, and intra-particle particle diffusion model) have been applied. Based on the calculated isotherm parameters (R²), it can be concluded that Langmuir model fits the adsorption equilibrium data better than Freundlich model, the results also indicated that the second order kinetic model is the best representative for adsorption of Sr(II) on GO, Chitosan and GO-Chitosan. Based on the regressions of intraparticle diffusion model, experimental data showed that the adsorption process involved intraparticle diffusion, which was not the only rate-controlling step.     

有机酸酯水解对水性聚氨酯凝聚的影响

介绍了水性聚氨酯热敏凝聚的原理和优点,研究了有机酸酯热敏剂水解作用下的羧酸盐阴离子型水性聚氨酯的凝聚过程,讨论了有机酸酯的种类、用量、水解温度等对羧酸盐阴离子型水性聚氨酯凝聚的影响。结果表明,引起羧酸盐阴离子型水性聚氨酯凝聚的酸度临界点是pH2.70,其中草酸二乙酯的热敏效果达到实验要求;热敏剂中草酸二乙酯与磷酸盐缓冲溶液的体积比大于5∶3,树脂与热敏剂的质量比在10∶1左右,热敏温度为80℃比较合适。     

Cs(I) and Sr(II) Sorption onto Graphene Oxide

This article demonstrates the efficacy of graphene oxide (GO) for Cs(I) and Sr(II) removal from aqueous solutions in the presence of competing cations. The interaction mechanisms of Cs(I) and Sr(II) with GO were studied at varying pHs, ionic strengths, and solution compositions. Thermal treatment was studied as a possible approach to minimize the volume of secondary radioactive waste, and cumulative pre-concentration factors were recorded for both cations.