High-energy treatment of sphagnum moss to produce carbon sorbents

The porous structure of amorphous carbon produced from sphagnum moss after chemical activation is considered. The ability of the amorphous carbon to adsorb metal ions is investigated. The results suggest that such carbon may serve as an effective sorbent.     

Formation of carbon nanofibers on the basis of sphagnum moss

The production of carbon nanofibers by the pyrolysis of sphagnum moss as a result of mechanochemical activation in a planetary mill is considered. The nanofibers are used to create a composite system consisting of carbon and tungsten nanoparticles, which may provide the basis for anodes in secondary power sources and may also be used in the mechanochemical synthesis and microalloying of refractory compounds.     

乙醇裂解协同制备氢气和碳纳米管

以乙醇为碳源,采用浸渍法制备的担载量为Fe(5%)/C催化剂,利用化学气相沉积法协同制备碳纳米管和氢气,分析了裂解温度(500⁸00℃)对于产生氢气产率和碳纳米管品质的影响。对于Fe(5%)/C催化裂解乙醇,最佳的反应温度为600℃,碳管的品质较好,氢气的产率最高为75%,生成的碳管为多壁碳纳米管。     

Processing low-grade oxidized coal to produce effective carbon sorbents

High-porosity sorbents may be produced by carbonization of low-grade oxidized coal in the presence of alkali.     

An easy way to produce α-iron filled multiwalled carbon nanotubes

α-Iron filled multiwalled carbon nanotubes were prepared through filling of commercially available carbon nanotubes, after oxidative opening, with ferrofluid particles. After washing and reduction with hydrogen clean tubes filled with α-iron were obtained.     

Functionalization of multi-walled carbon nanotubes with perfluoropolyether peroxide to produce superhydrophobic properties

Multi-walled carbon nanotubes (MWCNTs) have been functionalized through perfluoropolyether (PFPE) radicals obtained by thermal decomposition of linear PFPE peroxide. The reactivity of MWCNTs with PFPE peroxide has been compared with the direct fluorination of MWCNTs using elemental fluorine in mild conditions. The experimental results indicated that the functionalization with PFPE peroxide and the direct fluorination with elemental fluorine were suitable techniques to modify and control the physical-chemical properties of MWCNTs. After the introduction of PFPE chains on the MWCNT surface, the wettability of MWCNTs changed from hydrophilic to superhydrophobic, because the low surface energy properties of PFPE were transferred to the MWCNT surface. However, the linkage of PFPE chains weakly influenced the electrical properties of conductive MWCNTs. The amount of PFPE chains linked to the carbon nanotubes, the PFPE fluids obtained by homocoupling side-reactions and the decomposed portion of PFPE have been evaluated by mass balance. The modified MWCNTs have been characterized by X-ray photoelectron spectroscopy, thermal gravimetric analysis, X-ray diffraction, scanning electron microscopy, contact angle and surface area measurements. The effects of the chemical treatment on the conductive properties of MWCNTs have been studied by resistivity measurements at different applied pressures.     

The kinetics of sorption of basic dyes from aqueous solution by sphagnum moss peat

The kinetics of sorption of three basic dyes, namely, Chrysoidine (BO2), Astrazon Blue (BB3) and Astrazone Blue (BB69) onto sphagnum moss peat have been investigated. The study focuses on the application of three sorption kinetic models for predicting the uptake of basic dyes. The sorption behaviour is found to be second order, based on the assumption of a pseudo-second order mechanism. The rate constant of sorption, the equilibrium capacity and initial sorption rate with the effect of various peat doses and initial dye concentrations have also been predicted.     

Antioxidants in the water-soluble carbohydrate fractions of the moss Sphagnum fuscum and sphagnum peat

The effect of various mechanical treatment conditions on changes in the composition and antioxidant activity of the polysaccharide fractions of the moss Sphagnum fuscum and sphagnum moss peat was studied. It was found that mechanochemical treatment changed the composition of polysaccharide moss and peat fractions, and the antioxidant activity of polysaccharides depended on the hydroxyarene aglycon content of polysaccharides.     

An ionic liquid-assisted method for splitting carbon nanotubes to produce graphene nano-ribbons by microwave radiation

An ionic liquid-assisted splitting method for the production of graphene nano-ribbons from multi-wall or single wall carbon nanotubes was developed using microwave irradiation as an external energy source. Graphene nano-ribbons with a high aspect ratio can be produced by the ionic liquid assisted splitting action under microwave radiation. The technique involves neither oxidation with strong acids nor reduction with hydrazine and is a fast, simple, one-step procedure. Also, the present method can be extended to split and expand tubular graphite nanofibers. Our simple approach will make a new route for splitting carbon nanomaterials to form graphene nanoribbions in the hundred nanometers.     

The coupling of metallophthalocyanine with carbon nanotubes to produce a nanomaterial-based catalyst for reaction-controlled interfacial catalysis

A nanomaterial-based metallophthalocyanine catalyst (CoTAPc-MWCNTs) was prepared by covalently immobilizing cobalt tetraaminophthalocyanine (CoTAPc) on multiwalled carbon nanotubes (MWCNTs). The decomposition reaction of H₂O₂ was chosen to investigate the coupled catalytic performance. The results of electron paramagnetic resonance and online electrochemical experiments indicated that the catalytic mechanism of CoTAPc-MWCNTs is different from that of cobalt phthalocyanine molecular catalysts. The catalytic pathway of CoTAPc-MWCNTs involves the following steps: first, electron transfer from CoTAPc to H₂O₂ occurs through the coordination between the central cobalt ion and H₂O₂, reducing H₂O₂ to H₂O; second, electrons are transferred from MWCNTs to the oxidized CoTAPc, forming hole-doped MWCNTs; finally, hole-doped MWCNTs accept electrons from H₂O₂, oxidizing H₂O₂ to O₂. When using N,N-diethyl-1,4-phenylenediamine as a chromogenic substance, one obtained a quantitative estimate of holes injected in MWCNTs, corresponding to 1 hole for about 55 carbon atoms. Furthermore, CoTAPc-MWCNTs exhibit very unusual characteristics of controlled catalysis due to the special hydrophobic surface of the MWCNTs, and can be used as an interfacial catalyst for the determination of H₂O₂ concentration.     

Upscaling potential of the CVD stacking growth method to produce dimensionally-controlled and catalyst-free multi-walled carbon nanotubes

Multi-walled CNTs (MWCNTs) with structural characteristics optimised for bio-applications have been produced using a catalyst-supported chemical vapour deposition (CVD) method. The upscale potential of the process was demonstrated by combining classical semi-continuous and stacked-growth modes. The vertically aligned MWCNT films thus obtained were multi-layered with five continuous strata of well-structured nanotubes. Following gentle disentanglement, the stacks were converted to individual MWCNTs with short dimensions (a final length and diameter of ～1.2 μm and ～12 nm) and almost catalyst-free (<0.04%). Overall, our process produces dispersed, bio-tailored MWCNTs with an output growth-yield 20 times higher than a standard CVD setup and exempt of complex or destructive post-growth steps of purification and separation. These constitute key steps towards the mass production of MWCNTs with low toxicological risks, an essential prerequisite for biomedical applications.     

Processing and properties of syntactic foams reinforced with carbon nanotubes

This article presents synthesis and mechanical characterization of carbon nanotube (CNT)‐reinforced syntactic foams. Following a dispersion approach (comprising ultrasonic, calendering, and vacuum centrifugal mixing), single‐ and multi‐walled functionalized CNTs (FCNTs) were incorporated into two foam composites containing various commercially available microballoon grades (S38HS, S60HS, and H50 from 3M). The FCNT‐reinforced composites were tested for compressive strength and apparent shear strength before and after hot/wet conditioning. The results showed that the FCNT‐reinforced composites' mechanical properties depended on the vacuum pressure used during processing. Compared with pristine and commercially available syntactic foam (EC‐3500 from 3M), the FCNT‐reinforced composites processed at high vacuum (0.2 kPa) showed significant increase in compressive strength and apparent shear strength before and after hot/wet conditioning. Dynamic mechanical analysis showed an increase of about 22°C in glass transition temperature for composites processed at high vacuum with 0.5 wt % FCNT and 45 wt % S38HS–5 wt % S60HS microballoons. Thermogravimetric analysis indicated water absorption and lower decomposition temperature for the FCNT‐reinforced composite mixed at atmospheric pressure, whereas no significant change was observed for the compound processed at high vacuum. Fracture analysis showed matrix failure for the composite processed at high vacuum and microballoon crushing for the composite mixed at atmospheric pressure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Kinetics of formation of multiwall nanotubes from moss

The technological aspects of the formation of nanofibrous carbon (multiwall nanotubes from 10 to 70 nm in diameter) in the process of the mechanical activation of amorphous carbon (1–27 h), which was obtained by the pyrolysis of sphagnum moss at a temperature of 950°C are considered. The sequence of the formation of a nanofiber structure and the change in the physicochemical characteristics of the formed nanotubes are presented. It is shown that the formation of nanotubes occurs in the bulk of carbon particles.     

Processing and characterization of epoxy nanocomposites reinforced by cup-stacked carbon nanotubes

The effect of the dispersion, ozone treatment and concentration of cup-stacked carbon nanotubes on mechanical, electrical and thermal properties of the epoxy/CSCNT nanocomposites were investigated. Ozone treatment of carbon fibers was found to increase the surface oxygen concentration, thereby causing the contact angle between water, epoxy resin and carbon fiber to be decreased. Thus, the tensile strength, modulus and the coefficient friction of carbon fiber reinforced epoxy resin were improved. Moreover, the dispersion of fibers in polymer was increased and the electrical resistivity was decreased with the addition of filler content. The dynamic mechanical behavior of the nanocomposite sheets was studied. The storage modulus of the polymer was increased by the incorporation of CSCNTs. But the glass transition temperature decreased with increasing fiber loading for the ozone treated fiber composites. The ozone treatment did affect the morphology, mechanical and physical properties of the CSCNT.     

洋葱状碳纳米颗粒转化为碳纳米管的研究

以热固性酚醛树脂为碳源,以硝酸铁为催化剂前驱体制备洋葱状碳纳米颗粒。采用酸化方法使洋葱状纳米颗粒变成不稳定的球冠状态,在高温下使球冠进行重新组装,转化为形状不规则的碳纳米管,实现了材料转化。并详细分析了洋葱状碳纳米颗粒形成与转化为碳纳米管的机理。