Anhydrous organic dispersions of highly reduced chemically converted graphene

A straightforward, systematic approach to the reduction of graphene oxide (GO) that affords dispersions of chemically converted graphene (CCG) in anhydrous organic solvents with decreasing basal plane defects is reported. The extent of reduction can be controlled and optimized, resulting in highly reduced dispersible chemically converted graphene (hrCCG) having an O_1S/C_1S ratio of 0.06, which approaches that of graphite. The hrCCG dispersion in anhydrous dimethylformamide (DMF) was stable for several months at a concentration of 0.5–0.6 mg mL⁻¹. This process was found to be easily scalable and could be exploited for the large scale production of hrCCG in DMF and its dispersion in other anhydrous organic solvents. This study demonstrates that the stability of the graphene dispersion is critically dependent on the exfoliation process. The improved elimination of basal defects and the restoration of aromaticity, while maintaining dispersion stability on a large scale in an anhydrous organic solvent, greatly increase the potential of this material for a wide variety of applications.     

Electrochemical reduction of graphene oxide in organic solvents

Graphene oxide (GO) cast on conductive substrates was electrochemically reduced in some organic solvents. The amount of electricity required for the almost complete reduction of GO was 2.0 C for 1 mg GO, corresponding to attaching of a one-electron reducible species to each benzene ring in graphene. The electrochemically reduced GO film gave an electrical conductivity of about 3 S cm⁻¹ and exhibited a relatively high specific capacitance of 147.2 F g⁻¹ in propylene carbonate. The electrochemical reduction of GO was feasible on Al foils as well.     

Synthesis and electrochemical applications of the composites of conducting polymers and chemically converted graphene

Conducting polymers (CPs) have been widely applied for fabricating various electrochemical devices such as sensors, actuators, solar cells, etc. To extend the functions or improving the performances of the devices, CPs frequently have to be blended with other functional materials to form composites. Graphene, a one-atom layer of graphite with unique two-dimensional structure and excellent mechanical and electrical properties, has become an increasing star in material science. Chemically converted graphene (CCG) prepared by reducing graphene oxide has satisfied processing property and complementary properties with CPs. Therefore, CCG is an important functional component for preparing high-performance CP-based composites. In this critical review, we mainly summarize the recent advancements in our group on the synthesis of CP/CCG composites and their electrochemical applications including supercapacitors, solar cells and electroanalysis.     

石墨烯及化学改性石墨烯的胶状悬浮物合成研究进展

详细综述了石墨烯及化学改性石墨烯(CMG)的胶状悬浮物的合成工艺进展,从氧化石墨、氧化石墨烯及石墨其他衍生物的溶解性质和合成路径等方面展开论述。石墨烯的胶状悬浮物合成工艺既提供了大批量生产石墨烯的可能性,在化学改性修饰方面也有普遍的适用性。     

Effect of radical grafting of tetramethylpentadecane and polypropylene on carbon nanotubes' dispersibility in various solvents and polypropylene matrix

Multiwalled carbon nanotubes (MWCNTs) have been functionalized by tetramethylpentadecane (TMP), 1-dodecanethiol (DT) and polypropylene (PP) through radical addition onto MWCNTs' surface using dicumyl peroxide as hydrogen abstractor. Surface functionalized MWCNTs were characterized by Raman, IR spectroscopy, elementary analysis (EA) and thermogravimetric analysis (TGA). We studied the effect of temperature, peroxide concentration and solvent on TMP grafting densities and it was found that this surface treatment lead to a fair solubility in various solvents. TMP-functionalized MWCNTs were also imaged by transmission electronic microscopy showing single long functionalized MWCNTs distinct from the starting pristine bundles. For the first time, PP was then grafted onto MWCNTs through a radical grafting reaction. However, scanning electronic microscopy images of PP-functionalized MWCNTs/PP composites did not show a significant improvement in MWCNTs dispersion within the PP matrix.     

高含氮高浓度有机废水生物处理技术研究

分析了石家庄化纤公司己内酰胺生产废水的水质状况,指出该废水属高含氮、高浓度有机废水,虽然可生物降解性能较好,但因处理水在好氧硝化池(O1)中水力停留时间不够,难以达到硝化阶段,导致了原有生物处理工艺A／O／A／O系统无法正常运行。根据生物脱氮原理,提出了以SBR法作为处理工艺主体的ENSBR／BDAR／PCOR三段生物处理工艺。实验数据和生产运用表明,高含氮高浓度有机废水经该工艺处理后出水水质达到国家二级排放标准要求。     

Fenton氧化法预处理高浓度有机胺废水的研究

采用Fenton氧化法对高浓度有机胺废水进行预处理,研究了催化剂的种类、反应时间、过氧化氢投加量、催化剂的投加量对TOC去除率的影响。结果表明:在反应pH为3.0~3.5,反应温度30℃,过氧化氢投加质量分数为3.5%,混合催化剂的投加质量浓度为5 g/L条件下反应2.0 h,混合废水TOC可由815 mg/L降至315 mg/L,TOC去除率达到61.3%。分别对有机胺废水中的特征污染物——乙胺、二甲基乙醇胺、三乙醇胺进行预处理,去除率可分别达到35.5%、51.5%、61.8%。     

高浓度有机废水湿式氧化处理的研究现状

鉴于常规处理方法在高浓度有机废水处理方面存在的问题以及湿式氧化技术的巨大技术优势,文章介绍了国内外高浓度有机废水在湿式氧化处理的研究现状,评述了湿式氧化在催化剂失活、材料腐蚀、系统堵塞、投资成本过高等方面存在的问题以及控制方法,并给出了一些建议,以期对研究者有一定的参考。     

高浓度有机废水生物蒸发处理技术及展望

生物蒸发技术主要是利用高浓度有机废水自身所包含的有机物微生物好氧降解产生的热量为驱动力,使废水中的水分汽化,并配合适宜的通风,使蒸汽进入气相主体而散发,从而实现有机物和水分的同步去除。该过程主要受曝气量、堆体初始含水率及有机负荷影响。该技术在不需要外加热源的条件下,既可以实现水分有效蒸发去除,又对废水中的污染物质进行了有效降解,是一项经济、节能、环保的新技术。     

CWO法处理高浓度有机废水中催化剂的研究进展

湿式催化氧化法是一种有效处理高浓度、高毒性以及难生物降解有机废水的方法.作者对湿式催化氧化法进行了总体概述,重点介绍了湿式催化氧化法的分类,不同种类催化剂的优缺点及国内外研究进展和该方法在废水处理中的应用.对该技术的研究方向进行了展望,指出该领域催化剂的研究方向,为在铜系催化剂的研制基础上结合稀土类元素,在保证非均相催化剂高活性的前提下,减少活性组分的溶出,以提高催化剂的稳定性.     

还原温度对氧化石墨烯的湿度-甲醛交叉敏感性能的影响

以氧化石墨烯溶胶为前体,通过旋涂工艺制备薄膜型气敏元件,在低温80～180℃下进行热处理,获得系列不同还原程度的还原氧化石墨烯气敏元件,采用XRD、AFM、FT-IR、XPS对样品的层结构、薄膜厚度及含氧官能团变化属性进行表征,将气敏薄膜元件在相对湿度为11.3%～93.6%的范围内进行预湿处理,并测定元件对甲醛气氛的敏感性能。结果表明：随热还原处理温度的升高,氧化石墨烯的结构逐渐向类石墨结构转变,含氧官能团逐渐脱失,缺陷增多,薄膜的方块电阻呈数量级地减小,从41 MΩ减小至928 Ω;经不同湿度预处理的气敏元件置于甲醛气氛中产生了水分子与甲醛分子的竞争吸附,从而导致电阻的明显变化;在10^?4甲醛气氛下,未还原或热还原温度较低的气敏元件适用于低、高湿环境下甲醛气氛的气敏测试,最大灵敏度为69.1%,而还原温度适中的元件则适用于中湿环境的甲醛测试,最大灵敏度为80.3%。     

光化工艺处理染织厂高浓度有机废水

介绍了酸化水解—接触氧化—光化工艺在处理染织厂高浓度有机废水中的应用。采用先将高碱度高浓度染织废水进行冲灰除尘，节省了冲灰费用，而且可降低废水的pH和CODcr，再通过酸化水解—接触氧化—光化工艺处理，经过1a多的实践运行表明，该工艺处理效果好，运行稳定，能完全实现达标排放。在其他同类废水处理中值得借鉴。     

Effect of adsorption of organic solvents on the band profiles in reversed-phase non-linear chromatography

The influence of the mobile phase composition on the adsorption equilibria in non-linear reversed-phase chromatography has been investigated. RP-18 and RP-18 endcapped columns have been selected with methanol-water and acetonitrile-water as a mobile phase and cyclopentanone as a solute. Due to its structure, cyclopentanone exhibited affinity to the active adsorption sites on alkyl chains as well as to the polar, uncovered surface of the adsorbent. The adsorption equilibria of solvents—methanol-water, acetonitrile-water on RP-18 and RP-18e columns—have been measured and the excess adsorption isotherms accounting for non-ideality of the mobile and adsorbed phase have been determined. The competitive heterogeneous adsorption model for the solute and organic solvent has been proposed and coupled with a model of column dynamics. The model predictions have been verified by comparison to experimental chromatograms.     

Synthesis and characterizations of Ni-NiO nanoparticles on PDDA-modified graphene for oxygen reduction reaction

We are presenting our recent research results about the Ni-NiO nanoparticles on poly-(diallyldimethylammonium chloride)-modified graphene sheet (Ni-NiO/PDDA-G) nanocomposites prepared by the hydrothermal method at 90°C for 24 h. The Ni-NiO nanoparticles on PDDA-modified graphene sheets are measured by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) pattern for exploring the structural evidence to apply in the electrochemical catalysts. The size of Ni-NiO nanoparticles is around 5 nm based on TEM observations. The X-ray diffraction (XRD) results show the Ni in the (012), (110), (110), (200), and (220) crystalline orientations, respectively. Moreover, the crystalline peaks of NiO are found in (111) and (220). The thermal gravimetric analysis (TGA) result represents the loading content of the Ni metal which is about 34.82 wt%. The electron spectroscopy for chemical analysis/X-ray photoelectron spectroscopy (ESCA/XPS) reveals the Ni⁰ to Ni^II ratio in metal phase. The electrochemical studies with Ni-NiO/PDDA-G in 0.5 M aqueous H₂SO₄ were studied for oxygen reduction reaction (ORR).     

Effects of graphene oxide and chemically reduced graphene oxide on the curing kinetics of epoxy amine composites

The curing kinetics of epoxy nanocomposites prepared by incorporating graphene oxide (GO) and chemically reduced graphene oxide (rGO) have been studied using isothermal and nonisothermal differential scanning calorimetry. The kinetic parameters of the curing processes in these systems have been determined by a Kamal and Sourour phenomenological model expanded by a diffusion factor. The predicted curves determined using the kinetic parameters fit well with the isothermal DSC thermograms revealing the proposed kinetic equation clearly explains the curing kinetics of the prepared epoxy amine nanocomposites. Experimental and modeling results demonstrate the presence of an accelerating effect of the GO on the cure of the resin matrix. The use of rGO instead of GO resulted in a slight acceleration reaction rate due to the reduced presence of oxidation groups in rGO. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44803.     

Effect of protic solvents on the polarographic reduction of the alkali metal ions in hexamethylphosphoric triamide

Sodium and lithium ions are not reduced at the dropping mercury electrode in hexamethylphosphoric triamide containing 0.05 mol dm^?3 tetraethylammonium perchlorate while rubidium and caesium ions show diffusion controlled, l-electron reduction waves. The reduction of potassium ion is partially kinetic. When increasing amount of water is added to the solution, reduction waves of sodium and lithium begin to appear, and the kinetic contribution of potassium wave gradually disappears to give a diffusion controlled wave. The diffusion controlled waves of rubidium and caesium ions are essentially unaffected. The addition of methanol, ethanol, l-buthanol and dimethyl sulfoxide also has similar enhancing effects, which is attributed to the acceleration of the desolvation process by protons. These effects of protic solvent are apparently similar to that of the cation size of the supporting electrolytes, but of different origin, as indicated by the different behavior of the electrocapillary curves.     

Effect of precipitation bath composition on the primary swelling of yarns prepared from highly concentrated viscoses

Conclusions The magnitude of the primary swelling of viscose yarns prepared from highly concentrated viscoses in various stages of spinning has been determined as a function of the composition of the precipitation bath. The magnitude of forced syneresis has been calculated.Translated from Khimicheskie Volokna, No. 6, pp. 32–34, November–December, 1987.     

Effect of HCl on electrophoretic deposition of yttria stabilized zirconia particles in organic solvents

This study investigates the electrophoretic deposition (EPD) of YSZ particles onto a metal substrate from an organic solvent, the conductivity of which was manipulated by HCl additions. The green density is dependent on electrical conductivity and deposition time. It was found that a uniform coating with up to 67% relative green density could be produced after 10 min deposition from a 20 g/L suspension with electrical conductivity in the range of 10–15 μS/cm (0.5–0.7 mM HCl concentration). Direct measurements of the green YSZ coating density were supported by micro-indentation data using a spherical indenter.     

Electrochemical characterization of praseodymia doped zircon. Catalytic effect on the electrochemical reduction of molecular oxygen in polar organic solvents

The voltammetry of microparticles and scanning electrochemical microscopy methodologies are applied to characterize praseodymium centers in praseodymia-doped zircon (Pr_xZr_(1−y)Si_(1−z)O₄; y + z = x; 0.02 < x < 0.10) specimens prepared via sol–gel synthetic routes. In contact with aqueous electrolytes, two overlapping Pr-centered cathodic processes, attributable to the Pr (IV) to Pr (III) reduction of Pr centers in different sites are obtained. In water-containing, air-saturated acetone and DMSO solutions as solvent, Pr_xZr_(1−y)Si_(1−z)O₄ materials produce a significant catalytic effect on the electrochemical reduction of peroxide radical anion electrochemically generated. These electrochemical features denote that most of the Pr centers are originally in its 4+ oxidation state in the parent Pr_xZr_(1−y)Si_(1−z)O₄ specimens. The variation of the catalytic performance of such specimens with potential scan rate, water concentration and Pr loading suggests that Pr is not uniformly distributed within the zircon grains, being concentrated in the outer region of such grains.