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.     

碳材料复合橡胶研究进展

综述了各种碳材料复合橡胶的发展及研究进程,主要介绍了石墨烯、氧化石墨烯、碳纳米管等碳系材料结构、功能化方式及橡胶复合材料加工方法,得出各种碳材料不仅能较大改善橡胶的各种基础性能,而且赋予了橡胶很多新的功能,比如热量传导、电荷传输,因而能够提高橡胶产品性价比和档次。     

Comparative study of methylene blue dye adsorption onto activated carbon,graphene oxide,and carbon nanotubes

Three different carbonaceous materials, activated carbon, graphene oxide, and multi-walled carbon nanotubes, were modified by nitric acid and used as adsorbents for the removal of methylene blue dye from aqueous solution. The adsorbents were characterized by N₂ adsorption/desorption isotherms, infrared spectroscopy, particle size, and zeta potential measurements. Batch adsorption experiments were carried out to study the effect of solution pH and contact time on dye adsorption properties. The kinetic studies showed that the adsorption data followed a pseudo second-order kinetic model. The isotherm analysis indicated that the adsorption data can be represented by Langmuir isotherm model. The remarkably strong adsorption capacity normalized by the BET surface area of graphene oxide and carbon nanotubes can be attributed to π–π electron donor acceptor interaction and electrostatic attraction.     

Adsorption of 1,2-Dichlorobenzene from the Aqueous Phase onto Activated Carbons and Modified Carbon Nanotubes

This study aimed to describe the adsorption process of ortho-dichlorobenzene (o-DCB) onto activated carbons (ACs) and modified carbon nanotubes (CNTs) from the aqueous phase. The starting material NC_7000 carbon nanotubes were modified by chlorination (NC_C) and then by the introduction of hydroxyl groups (NC_C_B). The concentration of o-DCB in solutions was performed by UV-VIS spectrophotometry. After adsorption, the activated carbons were regenerated by extraction with organic solvents such as acetone, methanol, ethanol, and 1-propanol; the carbon nanotubes were regenerated by methanol. The degree of adsorbate recovery was determined by gas chromatography (GC) with flame ionization detection, using ethylbenzene as an internal standard. The equilibrium isotherm data of adsorption were satisfactorily fitted by the Langmuir equations. The results indicate that carbon adsorbents are effective porous materials for removing o-DCB from the aqueous phase. Additionally, activated carbons are more regenerative adsorbents than carbon nanotubes. The recoveries of o-DCB from ACs were in the range of 76–85%, whereas the recoveries from CNTs were in the range of 23–46%. Modifications of CNTs affect the improvement of their adsorption properties towards o-DCB compared to unmodified CNTs. However, the introduction of new functional groups on carbon nanotube surfaces makes the regeneration process less effective.     

Removal of nickel(II) from aqueous solution by carbon nanotubes

Single‐walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were oxidized by NaClO solutions and were employed as sorbents to study sorption characteristics of nickel(II) from aqueous solution. The surface properties of CNTs such as functional groups, total acidic sites and negatively charged carbons were greatly improved after oxidation, which made CNTs become more hydrophilic and resulted in sorption of more Ni²⁺. The amount of Ni²⁺ sorbed onto oxidized CNTs increased with a rise in agitation speed, initial Ni²⁺ concentration and solution pH in the range 1–8, but decreased with a rise in CNT mass and solution ionic strength. The sorption mechanisms are complicated and appear attributable to electrostatic forces and chemical interactions between the Ni²⁺ and the surface functional groups of the CNTs. The oxidized SWCNTs and MWCNTs have shorter equilibrium time and better Ni²⁺ sorption performance than the oxidized granular activated carbon, suggesting that both NaClO oxidized CNTs are efficient Ni²⁺ sorbents and that they possess good potential applications in water treatment. Copyright © 2006 Society of Chemical Industry     

Adsorption of copper(II) and EDTA‐chelated copper(II) onto granular activated carbons

Waste streams generated by electroless copper plating in the printed circuit boards manufacturing industry often contain copper complexed by strong chelating agents such as EDTA. The consequence of metal complexation by chelating agents is that alternative treatment to chemical precipitation is often necessary to achieve the low metal concentrations required by increasingly stringent environmental regulations. This paper examines the feasibility of using activated carbon to remove EDTA‐chelated copper(II) species as well as free copper(II) ions from aqueous solution. The adsorption characteristics of copper(II) and EDTA‐chelated copper(II) on two granular activated carbons prepared from coal and coconut shell were evaluated. Adsorption equilibrium data of copper(II) on the two carbons corresponded well to the Langmuir model. The coconut shell‐based carbon exhibited a greater adsorption capacity for copper(II) than the coal‐based carbon under similar experimental conditions. Solution pH had a considerable influence on copper(II) adsorption by the two carbons. Low adsorption levels of copper(II) at pH 3 and high adsorption levels in the pH range of 4–6 were observed. However, a reverse adsorption trend was observed when the chelating agent EDTA was added to the copper(II) solution. Adsorption of EDTA‐chelated copper(II) by the two carbons was higher at pH 3 than at pH 6. The contrasting adsorption behaviour of copper(II) ions and EDTA‐chelated copper(II) species can be readily explained in terms of electrostatic interaction in that solution pH influences the surface charge of the carbons as well as the charge property of copper(II) ions and EDTA‐chelated copper(II) species. © 2000 Society of Chemical Industry     

碳纳米管/石墨烯杂化材料改性环氧树脂研究

采用物理法和化学多步法合成了碳纳米管/石墨烯杂化材料,通过红外光谱表征证明杂化材料的成功合成,通过沉淀实验表明化学多步法合成的碳杂化材料具有良好的分散性和分散稳定性。将碳纳米杂化材料按照质量分数0.3%添加到环氧树脂(EP)中制备复合材料,对复合材料的拉伸强度和断裂韧性进行表征,并通过扫描电子显微镜对复合材料的断面进行表征。结果表明,碳纳米管/石墨烯杂化材料对EP的增强增韧效果较好,尤其是化学多步法合成的杂化材料改性EP复合材料,其拉伸强度最大,曲线积分面积最大,弹性模量最小,韧性最好。这可能要归因于化学多步法合成的杂化材料具有更为稳定的三维结构,可以更好地承担和转移外部载荷。     

多种碳材料与碳酸钠复合后脱硫性能对比

碳材料本身对于H₂S的净化效果有限,通过将活性催化剂负载到活性炭上可以弥补碳材料脱除H₂S气体能力的不足。本文选用三种具有典型孔隙结构的碳材料：微孔活性碳纤维、中孔活性炭以及孔隙更大的单壁碳纳米管,等体积浸渍不同浓度的碳酸钠溶液制作负载活性材料的脱硫剂,应用固定床反应实验评价不同负载量下制得脱硫剂的脱硫性能,并对材料进行表征测试。经过对比,具有发达微孔结构的活性碳纤维材料整体上具有最佳的脱硫性能,且活性物质的负载量并不是越大越好。实验条件下,在出口逐渐检测到SO₂以及H₂S两种气体,其中SO₂气体出现较早。测定各类碳材料负载以及脱硫前后的表面pH,发现负载Na₂CO₃后材料表面pH得到大幅度提升,而脱硫后的材料表面pH均有不同程度的下降。     

Grafting of alkoxyamine end-capped (co)polymers onto multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWNTs) have been successfully modified by polystyrene, poly(?-caprolactone), and their block copolymers by addition reaction of the alkoxyamine-terminated precursors. Polymer-modified MWNTs are easily dispersed in good solvents for the grafted polymer, such as toluene and THF. This observation has been confirmed by TEM analysis. The grafting ratio of polystyrene chains at the surface of MWNTs depends on the polymer molecular weight.     

国内天然气干法脱硫剂的比较研究

概述了国内天然气干法脱硫技术及其应用情况,并对T103、T703和DS-1脱硫剂与目前国内市场上广泛应用的活性炭脱硫剂A进行了对比实验。实验结果表明,T103的穿透硫容比脱硫剂A高出近一倍,完全能满足工业生产要求;T703和DS-1的脱硫效果也略好于脱硫剂A。     

碳纳米管对活性污泥胞外聚合物的吸附特性研究

以单壁碳纳米管(SWNTs)为吸附剂,系统地研究了其对活性污泥胞外聚合物(EPS)的吸附特性.结果表明,SWNTs能够快速吸附EPS,当吸附剂投加量为0.9 g/L时,吸附在20 min即可达到平衡,吸附动力学符合准二级动力学模型.吸附等温线能较好地用Langmuir 吸附等温模型来描述,最大单分子吸附量为123.577 mg/g.pH值对吸附有较大影响,最佳吸附pH范围为5～7.     

Water Sorption and Diffusion in (Reduced) Graphene Oxide‐Alginate Biopolymer Nanocomposites

The water sorption and diffusion in (reduced) graphene oxide‐alginate composites of various compositions is analyzed. Water sorption of sodium alginate can be significantly reduced by the inclusion of graphene oxide sheets due to the formation of an extensive hydrogen bonding network between oxygenated groups. Crosslinking alginate with divalent metal ions and the presence of reduced graphene oxide can further improve the swelling resistance due to the strong interactions between metal ions, alginate, and filler sheets. Depending on conditions and composition, the overall water barrier properties of alginate composites improve upon (reduced) graphene oxide filling, making them attractive for moisture barrier coating applications. Water sorption kinetics in all alginate composites indicate a non‐Fickian diffusion process that can be accurately described by the Variable Surface Concentration model. In addition, the water barrier properties of sodium alginate‐graphene oxide composites can be adequately predicted using a simple model that takes the orientational order of filler sheets and their effective aspect ratio into account.

     

活性炭负载Fe(III)吸附剂去除饮用水中的As(V)

利用活性炭负载水合铁氧化物制备了复合吸附剂,并用于饮用水中As(V)的去除. 研究了活性炭种类、粒度、溶液pH值、Fe(III)盐浓度和干扰离子等对As(V)去除的影响. 结果表明,煤质活性炭作为基质负载水合铁氧化物比椰壳炭和果壳炭具有更好的除砷效果. 随着炭粒度降低,除砷效率显著增加. 在pH 3~9范围内,活性炭负载水合铁氧化物可有效吸附As(V). F-, Cl-, SO42-的加入对As(V)的去除效率基本无影响,而SiO32-和PO43-则明显抑制As(V)的去除. Langmuir模型比Freundlich模型能更好地描述复合吸附剂对As(V)的吸附平衡. 动力学研究表明,As(V)吸附反应可用二级速率方程描述.     

Investigation of the effect of functionalized carbon nanotube and graphene oxide in guar gum-based mixed matrix membrane for gas separation application

The present study deals with preparing mixed matrix membranes (MMMs), a new polysaccharide-based natural polymer used as a matrix with functionalized carbon nanotubes (FCNTs) and graphene oxide (GO) used as an inorganic filler. This work identified the effect of the inorganic fillers (FCNTs or GO) with naturally occurring polymer for gas separation. The incorporation of fillers improves the gas separation performance of MMMs. In GG/FCNTs MMMs, the selectivities of CO₂/N₂ and CO₂/H₂ were enhanced by 55.24% and 57.89%, respectively. Moreover, in GG/GO MMMs, the selectivities of CO₂/N₂ and CO₂/H₂ were improved by 99.50% and 50%, respectively. The membrane was characterized by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The SEM analysis of GG/GO MMMs reveals layered structure, and GG/FCNTs MMMs create passages to transport gases. The Universal testing machine (UTM) is used to analyze the mechanical properties of pristine and modified membranes.     

Adsorption of zinc(II) from water with purified carbon nanotubes

Commercial single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) were purified by sodium hypochlorite solutions and were employed as adsorbents to study the adsorption characteristics of zinc from water. The properties of CNTs such as purity, structure and nature of the surface were greatly improved after purification which made CNTs become more hydrophilic and suitable for adsorption of Zn²⁺. In general, the adsorption capacity of Zn²⁺ onto CNTs increased with the increase of pH in the pH range of 1-8, fluctuated very little and reached maximum in the pH range of 8-11 and decreased at a pH of 12. A comparative study on the adsorption of Zn²⁺ between CNTs and commercial powdered activated carbon (PAC) was also conducted. The maximum adsorption capacities of Zn²⁺ calculated by the Langmuir model are 43.66, 32.68, and with SWCNTs, MWCNTs and PAC, respectively, at an initial Zn²⁺ concentration range of 10-. The short contact time needed to reach equilibrium as well as the high adsorption capacity suggests that SWCNTs and MWCNTs possess highly potential applications for the removal of Zn²⁺ from water.     

Cyclic Sorption and Desorption of Cu(II) onto Coconut Shell and Iron Oxide Coated Sand

Sorption is a viable treatment technology for copper-rich gold mine tailings wastewater. For continuous application, the sorbent should be regenerated with an appropriate desorbent, and reused. In this study, the sequential sorption/desorption characteristics of Cu(II) on coconut shell (CS) and iron oxide coated sand (IOCS) were determined. In batch assays, CS was found to have a Cu(II) uptake capacity of 0.46 mg g^?1 and yielded a 93% removal efficiency, while the IOCS had a Cu(II) uptake capacity and removal efficiency of 0.49 mg g^?1 and 98%, respectively. Desorption experiments indicated that HCl (0.05 M) was an efficient desorbent for the recovery of Cu(II) from CS, with an average desorption efficiency of 96% (sustained for eight sorption and desorption cycles). HCl (0.05 M) did not diminish the CS's ability to sorb copper even after eight sorption/desorption cycles, but completely deteriorated the iron oxide structure of the IOCS within six cycles. This study showed that CS and IOCS are both good sorbents for Cu(II); but cyclical sorption/desorption using 0.05 M HCl is only feasible with CS.     

Comparative study of physico-mechanical performance of PPC mortar incorporated 1D/2D functionalized nanomaterials

The current study investigates the effect of adding graphene oxide (GO) and functionalized multiwalled carbon nanotubes (FMWCNTs) in pozzolana Portland cement (PPC) mortars to evaluate their mechanical and electrical resistivity properties. The effects of 1D and 2D functionalized carbon nanomaterials in PPC have been studied. At 90 days of curing, the g1PPC (.0015% of GO by weight percentage of binder) and c1PPC (.0015% of FMWCNTs by weight percentage of binder) showed a significant improvement in the physico-mechanical performance of the pozzolana Portland cement composited (PPCC) mortars. The enhanced compressive strength was found to be 11.67% and 8.74% for g1PPC and c1PPC, respectively, as compared to the control specimen (PPC-C). The increased tensile splitting strength was observed to be 26.39% and 20.61% for g1PPC and c1PPC, respectively, as compared to PPC-C. The electrical resistivity of PPCC mortars have been shown a significant improvement for g1PPC and c1PPC. This might be due to the densification of calcium silicate hydrate (C–S–H) gel and hydration products. Powdered X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR). Field emission-scanning electron microscope (FE-SEM) was able to support the improved strength of PPCC mortars via formation of ettringite and needle-shaped crystals in hydrated products.     

Adsorption characteristics of toxic chromium(VI) from aqueous media onto nanosized silver nanoparticles-treated activated carbon

The present study reports the use of nanomaterial, e.g. Ag nanoparticles (AgNPs), immobilized activated carbon as an effective solid adsorbent for removal of toxic chromium(VI) from water. Chromium(VI) uptake was found favorable in acidic media at pH ≤ 3. Based on Langmuir model, monolayer adsorption capacities of chromium(VI) found equal 93.5 mg/g. The results fitted well with pseudo second-order and Langmuir models. The mechanism of adsorption was explored using the intra-particle diffusion model and the liquid-film model. Chromatographic separation of chromium(VI) was achieved. The AC-AgNPs was successfully recycled for five successive adsorption–desorption cycles indicating its high reusability.     

Synthesis of hydrophobic carbon nanotubes/reduced graphene oxide composite films by flash light irradiation

Carbon nanotubes/graphene composites have superior mechanical, electrical and electrochemistry properties with carbon nanotubes as a hydrophobicity boosting agent. Their extraordinary hydrophobic performance is highly suitable for electrode applications in lithium ion batteries and supercapacitors which often employ organic electrolytes. Also the hydrophobic features enable the oil enrichment for the crude oil separation from seawater. The ever reported synthesis routes towards such a composite either involve complicated multi-step reactions, e.g., chemical vapor depositions, or lead to insufficient extrusion of carbon nanotubes in the chemical reductions of graphene oxide, e.g., fully embedding between the compact graphene oxide sheets. As a consequence, the formation of standalone carbon nanotubes over graphene sheets remains of high interests. Herein we use the facile flash light irradiation method to induce the reduction of graphene oxides in the presence of carbon nanotubes. Photographs, micrographs, X-ray diffraction, infrared spectroscopy and thermogravimetric analysis all indicate that graphene oxides has been reduced. And the contact angle tests confirm the excellent hydrophobic performances of the synthesized carbon nanotube/reduced graphene oxide composite films. This one-step treatment represents a straightforward and high efficiency way for the reduction of carbon nanotubes/graphene oxides composites.

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