| 1. |
- Chen, Long, et al.
(författare)
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Facile synthesis of mesoporous carbon nanocomposites from natural biomass for efficient dye adsorption and selective heavy metal removal
- 2016
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:3, s. 2259-2269
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous carbon with embedded iron carbide nanoparticles was successfully synthesized via a facile impregnation–carbonization method. A green biomass resource, cotton fabric, was used as a carbon precursor and an iron precursor was implanted to create mesopores through a catalytic graphitization reaction. The pore structure of the nanocomposites can be tuned by adjusting the iron precursor loadings and the embedded iron carbide nanoparticles serve as an active component for magnetic separation after adsorption. The microstructure of the nanocomposites was carefully investigated by various characterization techniques including electron microscopy, X-ray diffraction, surface analyzer, magnetic property analyzer and etc. The newly created mesopores are demonstrated as a critical component to enhance the adsorption capacity of organic dyes and embedded iron carbide nanoparticles are responsible for the selective removal of heavy metal ions (Zn2+, Cu2+, Ni2+, Cr6+ and Pb2+). Isotherm adsorption, kinetic study at three different temperatures (25, 45 and 65 °C) and cycling retention tests were performed to understand the adsorptive behavior of the nanocomposites with organic dyes (methylene blue and methyl orange). Together with the preferable removal of more toxic heavy metal species (Cr6+ and Pb2+), these mesoporous nanocomposites show promising applications in pollutant removal from water. The facile material preparation allows convenient scale-up manufacturing with low cost and minimum environmental impact.
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| 2. |
- Ji, Tuo, et al.
(författare)
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Green Processing of Plant Biomass into Mesoporous Carbon as Catalyst Support
- 2016
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 295, s. 301-308
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Tidskriftsartikel (refereegranskat)abstract
- Four different plant biomass, bamboo, cotton, soft wood and hard wood, were utilized as carbon precursors to fabricate porous carbon catalyst supports via a chemical free approach. Large surface area with unique mesoporous structure was successfully created in the carbon, which made them suitable for catalyst support. After decorating silver nanoparticles onto these carbon supports, nitroaromatics reduction reactions were performed to evaluate the catalyst activity. Results indicate that chemical composition and surface groups of carbon supports determine the metal catalyst nucleation/growth while the porous microstructure of support affects the mass transport of reactant/product across the liquid/catalyst interface. Among the four selected biomass, porous carbon manufactured from soft wood acquires the highest average pore size, pore volume, mesopore volume fraction and best catalytic activity after decorating silver nanoparticles. This work not only presents an environmental benign process that converts natural biomass into effective porous carbon catalyst supports, but also offers a comprehensive understanding of biomass structure/composition relating to their suitability as catalyst support.
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| 3. |
- Mu, Liwen, et al.
(författare)
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Enriching Heteroelements in Lignin as Lubricating Additives for Bioionic Liquids
- 2016
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 4:7, s. 3877-3887
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Tidskriftsartikel (refereegranskat)abstract
- Depolymerization and modification of lignin have been achieved simultaneously in a one-pot chemical reaction. Two heteroelement-rich modifiers, imidazol-1-yl phosphonic dichloride and 1H-1,2,4-triazol-1-yl phosphonic dichloride, were selected to react with lignin in this work. The modified lignin (m-lignin) is demonstrated as an effective lubricating additive for [choline][amino acid] ([CH][AA]) bioionic liquids. Different characterization techniques have been utilized to study the lignin depolymerization, reaction between lignin and modifiers and m-lignin/[CH][AA] interaction. The effect of the molecular structure of the modifiers on the rheological and tribological properties of m-lignin/[CH][AA] lubricants was systematically investigated. Density function theory is used to calculate the electronic structure of lignin, m-lignin, and [CH][AA]. The atomic natural charge analysis revealed the most negative charge on nitrogen bonded to a phosphorus atom and the strongest capability of forming hydrogen bonding with [CH][AA]. The introduced nitrogen and phosphorus elements not only increase the hydrogen bonding density in m-lignin/[CH][AA] but also enhance the polarity of the m-lignin, both of which facilitate a strong adhesion of lubricant on a metal surface and thus promote lubrication. A larger fraction of heteroatom groups in m-lignin contributes to a better lubrication property of these lubricants
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| 4. |
- Mu, Liwen, et al.
(författare)
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Ionic Grease Lubricants : Protic [Triethanolamine][Oleic acid] and Aprotic [Choline][Oleic acid]
- 2016
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:7, s. 4977-4984
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Tidskriftsartikel (refereegranskat)abstract
- Ionic liquid lubricants or lubricant additives have been studied intensively over past decades. However, ionic grease serving as lubricant has rarely been investigated so far. In this work, novel protic [Triethanolamine][Oleic acid] and aprotic [Choline][Oleic acid] ionic greases are successfully synthesized. These ionic greases can be directly used as lubricants without adding thickener or other additives. Their distinct thermal and rheological properties are investigated and well correlated to their tribological properties. It is revealed that aprotic ionic grease shows superior temperature and pressure tolerant lubrication properties than protic ionic grease. The lubrication mechanism is studies and it reveals that strong physical adsorption of ionic grease onto friction surface plays a dominating role for promoted lubrication instead of tribo-chemical film formation.
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| 5. |
- Mu, Liwen, et al.
(författare)
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Lignin in Ethylene Glycol and Poly(ethylene glycol) : Fortified Lubricants with Internal Hydrogen Bonding
- 2016
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 4:3, s. 1840-1849
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Tidskriftsartikel (refereegranskat)abstract
- Lignin, one of the most naturally abundant polymers, has been successfully incorporated into ethylene glycol (EG) and poly(ethylene glycol) (PEG) in this work and fortified lubricating properties were achieved in EG/lignin and PEG/lignin. The molecular interaction between lignin and EG (or PEG) has been revealed as hydrogen bonding, which serves as the dominating factor that determines the thermal, rheological, and tribological properties of the mixed systems of EG/lignin and PEG/lignin. The physicochemical properties of the mixed lubricants are tightly related to the state of internal hydrogen bonding (EG–EG, PEG–PEG, EG–lignin, PEG–lignin, and lignin–lignin) and are well correlated to their lubrication properties. Generally, larger lignin fractions lead to better lubricating performance in both EG and PEG systems. Lignin liquefaction in PEG has been addressed by catalytic degradation with the presence of sulfuric acid, which was then neutralized by triethanolamine for lubricant development. Lignin in PEG significantly improves the lubricating property at higher pressure conditions, where a wear reduction of 94.6% was observed. Lignin fortified EG and PEG based lubricants show outstanding noncorrosive characteristic to the mostly used metal materials such as aluminum and iron.
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| 6. |
- Mu, Liwen, et al.
(författare)
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Paving the Thermal Highway with Self-Organized Nanocrystals in Transparent Polymer Composites
- 2016
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:42, s. 29080-29087
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Tidskriftsartikel (refereegranskat)abstract
- Phonon transfer is greatly scattered in traditional polymer composites due to the unpaired phonon frequency at the polymer/filler interface. A key innovation of this work is to build continuous crystal network by self-organization and utilize it as “thermal highway” that circumvents the long-existing interfacial thermal barrier issue in traditional composites. By tuning the molecular diffusion rate of dicarboxylic acids (oxalic acid, malonic acid, and succinic acid), different crystal structures including skeletal, dendrite, diffusion-limited aggregates, and spherulite were synthesized in PVA film. These continuous crystal structures benefit the efficient phonon transfer in the composites with minimized interfacial scattering and lead to a significant thermal conductivity enhancement of up to 180% compared to that of pure polymer. Moreover, the transparent feature of these composite films provides additional benefits in display applications. The post heat treatment effect on the thermal conductivity of the composite films shows a time-dependent behavior. These uniquely structured polymer/crystal composites are expected to generate significant impacts in thermal management applications.
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| 7. |
- Wu, Jian, et al.
(författare)
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High load capacity with Ionic liquid-lubricated tribological system
- 2016
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 94, s. 315-322
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Tidskriftsartikel (refereegranskat)abstract
- Engineering polymers with high glass transition temperature have been widely used in dynamic friction systems by oil or solid lubrication. However, in high-load systems, oil lubrication is less efficient due to the viscosity decrease at higher temperatures induced by friction heat. [Bmim][PF6] ionic liquid was used and compared with traditional L-HM46 oil and solid PTFE. Taking advantage of high [Bmim][PF6] viscosity, strong steel-[Bmim][PF6] but poor PEEK-[Bmim][PF6] interaction, the [Bmim][PF6] lubricated PEEK/steel slide falls in hydrodynamic lubrication and elastohydrodynamic lubrication region under 150–1500 N. While the oil and PTFE both failed to lubricate under 800 N.
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