Materials
·
2018
·Vol. 11
·期 5
·727
·
IF 2.467
Zhe Wang,Xiaoping Shen,Temeng Qian,Junjie Wang,Qingfeng Sun,Chunde Jin
The disadvantages such as swelling after absorbing water and flammability restrict the widespread applications of lignocellulose composites (LC). Herein, a facile and effective method to fabricate superhydrophobic surfaces with flame retardancy on LC has been investigated by coating polydimethylsiloxane (PDMS) and stearic acid (STA) modified kaolin (KL) particles. The as-prepared coatings on the LC exhibited a good repellency to water (a contact angle = 156°). Owing to the excellent flame retardancy of kaolin particles, the LC coated with PDMS@STA-KL displayed a good flame retardancy during limiting oxygen index and cone calorimeter tests. After the coating treatment, the limiting oxygen index value of the LC increased to 41.0. Cone calorimetry results indicated that the ignition time of the LC coated with PDMS@STA-KL increased by 40 s compared with that of uncoated LC. Moreover, the peak heat release rate (PHRR) and the total heat release (THR) of LC coated with PDMS@STA-KL reduced by 18.7% and 19.2% compared with those of uncoated LC, respectively. This LC coating with improved water repellency and flame retardancy can be considered as a potential alternative to protect the lignocellulose composite.Keywords:lignocellulose composites;kaolin;PDMS;superhydrophobic;flame retardancy
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PubMed
高影响因子
IRANIAN POLYMER JOURNAL
·
2015
·Vol. 24
·期 3
·219-227
·
IF 1.806
Lü Ting,Liu Xingyuan,Qi Dongming,Zhao Hongting
Aqueous dispersion polymerization has been considered as a promising green technology for preparing water-soluble polymers such as cationic polyacrylamide (CPAM). Dispersion copolymerization of acrylamide and 2-methylacryloylxyethyl trimethyl ammonium chloride was generally carried out in aqueous ammonium sulfate solution with poly(2-methylacryloylxyethyl trimethyl ammonium chloride) as the stabilizer. In this study, we reported the potential influence of a small amount of hydrophobic monomer, methyl methacrylate (MMA), on the above-mentioned aqueous dispersion polymerization system. It was found that MMA could play an important role in the polymerization process by significantly affecting the particle formation and stabilization, as well as the viscosity evolution of the reaction mixture during polymerization. With the addition of a small amount of MMA, the particle formation was accelerated and the viscosity of the polymerization system decreased significantly. With the increase in MMA addition, the final copolymer particle size was reduced and its size distribution became narrower; meanwhile, the particle morphology tended to be spherical. Moreover, it was found that the addition of MMA could favor the production of CPAM with high charge density. The flocculation performance of the resulting CPAM dispersion was also examined in detail and it was found that the introduction of MMA unit into CPAM molecular chain could improve its flocculation efficiency.
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高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2015
·
IF 4.529
Hangcheng Zhu,Yong Zhang,Xiaogang Yang,Hongyi Liu,Lan Shao,Xiumei Zhang,Juming Yao
The waste management of used flocculants is a thorny issue in the field of wastewater treatment . To natural cellulose based flocculants, utilization of hazardous cellulose solvent and simplification of synthetic procedure are the two urgent problems needing to be further improved. In this work, a series of natural dicarboxyl cellulose flocculants (DCCs) were one-step synthesized via Schiff-base route. The cellulose solvent (NaOH/Urea solution) was utilized during the synthesis process. The full-biodegradable flocculants avoid causing secondary pollution to environment. The chemical structure and solution property of the DCC products were characterized by FT-IR, 1 H NMR, 13 C NMR, TGA, FESEM , charge density and ζ-potential. Kaolin suspension and effluent from paper mill were selected to evaluate the flocculation activity of the DCCs. Their flocculation performance was compared with that of commercial cationic polyacrylamide and poly aluminium chloride flocculants. The positive results showed that the NaOH/Urea solvent effectively promoted the dialdehyde cellulose (DAC) conversion to DCC in the one-step synthesis reaction. The DCCs with the carboxylate content more than 1 mmol/g exhibited steady flocculation performance to kaolin suspension in the broad pH range from 4 to 10. Its flocculation capacity to the effluent from paper mill also showed excellent.
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PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2014
·Vol. 132
·期 13
·
IF 1.64
Chongyi Li,Feng Xue,Enyong Ding
This is probably the first report on the synthesis of a series of novel collagen-based flocculants (CP11, CP12, and CP13) by grafting polyacrylamide (PAM) chains onto the collagen backbone, which was directly extracted from leather shavings via alkali hydrolysis. The results from FTIR, XRD, 1 H NMR, and TGA well supported that PAM chains had been successfully grafted onto collagen backbone. In addition, the micrographs of SEM revealed that the PAM grafted collagen possessed much more porous and looser surface structures in comparison with virgin collagen. Zeta potential measurement showed that the introduction of branched PAM chains helped to improve the positively charge density. Furthermore, CP12 performed the best in the kaolin flocculation with the highest flocculation rate about 24%·min −1 and could induce the generation of much larger and denser floccs for the fast settling of kaolin particles. The corresponding flocculation mechanism was also presented by analyzing the collected flocs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 41556.
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高影响因子
ACS Sustainable Chemistry & Engineering
·
2016
·
IF 5.267
Hou-Yong Yu,Dong-Zi Zhang,Fang-Fang Lu,Juming Yao
A simple approach was developed to isolate cellulose nanocrystals (CNCs) with carboxylic groups from microcrystalline cellulose (MCC). The effect of reaction time on the morphology, microstructure, and thermal stability of isolated CNCs was investigated. The rod-like CNCs with size of 200–250 nm in length and about 15–20 nm in width were obtained by one-step citric/hydrochloric acid (C6H8O7/HCl) hydrolysis of MCC. The CNCs extracted at 4 h showed the highest carboxylic group content which led to a high absolute zeta potential value up to 46.63 mV. Moreover, these CNCs may be used as cationic dye adsorbent (methylene blue) and efficient flocculants with excellent coagulation–flocculation capability to kaolin suspension with a turbidity removal of 99.5%.
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高影响因子
CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
Ting Chen,Ming Duan,Shenwen Fang
Hierarchically engineered asymmetric ceramic membrane is successfully fabricated, and special wettability is endowed to the membrane by introducing superhydrophilic and underwater superoleophobic silica nanoparticles through dip-coating technology onto the active separation layer. Effect of reaction temperature on the wettability of the silica nanoparticles is discussed. It has been found that the hydrophilicity of the silica increases with increasing the temperature and superhydrophilicity can be obtained when the temperature reaches to 60 °C. Underwater oil contact measurements are performed using a series of oils and it turns out the as-prepared material bear excellent oil repellency towards various oil droplets. Separation performance of the membrane for oily wastewater treatment was investigated. It has been revealed that the as-prepared membrane can successfully separate the oil contaminated wastewater within one step under a small applied pressure (0.1 MPa) with oil rejection coefficient R >99.95%, indicating an extremely high separation efficiency.
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高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2016
·
IF 2.567
Lilu Qin,Liangguo Yan,Jian Chen,Tiantian Liu,Haiqin Yu,Bin Du
The amino-functionalized magnetite/kaolin clay (MKC) was synthesized via a simple solvothermal method and used to remove Pb2+, Cu2+, and Cd2+ from aqueous solutions. In comparison, the kaolin clay (KC) and MKC were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopy with energy dispersive spectrometry. The results indicated amino-functionalized MKC was formed with Fe3O4 particles adhering to the surface by interactions with negatively charged KC. The optimal experimental conditions were evaluated, and the adsorption performance of MKC for Pb2+, Cu2+, and Cd2+ was far better than that of KC. This was mainly caused by adding an amino group, in which the amino group displayed complexing ability toward metal ions. In kinetic data representation, the pseudo-first-order, pseudo-second-order, and Elovich models were employed, and the second one gave the better fitting. Langmuir, Freundlich, and Dubinin–Radushkevich models were chosen for isotherm data correlation, of which the first one showed better suitability. The X-ray photoelectron spectroscopy analysis of MKC before and after adsorption further revealed that the adsorption mechanisms of Pb2+, Cu2+, and Cd2+ could be a combined reaction of complexation between functional groups and metal ions and electrostatic attraction. In addition, MKC can be rapidly separated using only a magnet after the adsorption process.
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高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2016
·
IF 2.101
Qiang Huang,Meiying Liu,Fengjie Deng,Ke Wang,Hongye Huang,Dazhuang Xu,Guangjian Zeng,Xiaoyong Zhang,Yen Wei
Adsorption has been well regarded as a promising and efficient method for the removal of low concentration heavy metal ions in aqueous solutions. And kaolin has been considered as a kind of low cost and environment-friendly adsorbent for its abundant in nature. But the low adsorption capacity to heavy metal ions and severe aggregation in solution restrains its application. In this work, an environment-friendly adsorbent (denoted as Kaolin-PDA-PEI) was prepared based on mussel inspired chemistry and Michael addition reaction between high reaction activity of polydopamine (PDA) and polyethyleneimine (PEI), which was possesses a number of amine groups. The amine groups have displayed strong adsorption affinity towards copper ions . The successful modification of Kaolin by PDA and PEI was confirmed by a series of analyses, such as Fourier transform infrared spectroscopy , transmission electron microscopy , thermal gravimetry analysis and X-ray photoelectron spectroscopy. The effects of various parameters such as contact time, pH, initial concentrations of copper ions and temperature on copper ion adsorption by Kaolin-PDA-PEI were investigated. Kaolin-PDA-PEI shows higher adsorption capacity as compared with the raw Kaolin. The kinetic adsorption data were analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion model. The Langmuir isotherm and Freundlich isotherm equilibrium model were applied to adsorption isotherm data to find the better fit isotherm. The results showed that adsorption process was well fitted by Langmuir isotherm model. The values of thermodynamics constants such as entropy change ( ΔS 0 ), enthalpy change ( ΔH 0 ) and Gibbs free energy ( ΔG 0 ) were also calculated. The results indicated that the adsorption process of Kaolin-PDA-PEI were endothermic and spontaneous.
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2016
·Vol. 51
·期 17
·8116-8130
·
IF 2.302
Huang Qiang,Liu Meiying,Chen Junyu,Wang Ke,Xu Dazhuang,Deng Fengjie,Huang Hongye,Zhang Xiaoyong,Wei Yen
Adsorption is an effective and commonly adopted method for removal of organic pollutants from environment. In this work, we described the synthesis and the adsorption behavior of poly(sodium p-styrenesulfonate hydrate) (PSPSH)-modified kaolin, which was obtained by combination of mussel-inspired chemistry and Michael addition reaction. The amino-terminated PSPSH was synthesized by free radical polymerization using cysteamine hydrochloride as the chain transfer agent and sodium p-styrenesulfonate hydrate as the monomer. Raw kaolin and PSPSH-modified kaolin were characterized using several techniques including transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and X-ray photoelectron spectroscopy in detail. The adsorption of methylene blue onto modified kaolin from aqueous solution was investigated, in which the effects of contact time, temperature, solution pH, and initial methylene blue concentration were studied. The experiment data were analyzed using two common adsorption models: Langmuir and Freundlich isotherm models. The kinetic adsorption data were analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion model. The values of thermodynamics constants such as entropy change (Δ S
0 ), enthalpy change (Δ H
0 ) and Gibbs free energy (Δ G
0 ) were also determined. The modified kaolin showed favorable dispersibility and convenient separation, high efficiency, and good regeneration capability in the removal of methylene blue from solution.
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高影响因子
APPLIED ENERGY
·
2016
·
IF 5.746
Peizhao Lv,Chenzhen Liu,Zhonghao Rao
In this paper, different particle sizes of kaolin were employed to incorporate paraffin via vacuum impregnation method. The paraffin/kaolin composites were characterized by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimeter (DSC) and Thermogravimetry (TG). The results showed that the paraffin/kaolin composite with the largest particle size of kaolin (K4) has the highest thermal conductivity (0.413 W/(m K) at 20 °C) among the diverse composites. The latent heat capacity of paraffin/K4 is 119.49 J/g and the phase change temperature is 62.4 °C. In addition, the thermal properties and thermal conductivities of paraffin/K4 with different mass fraction of K4 (0–60%) were investigated. The thermal conductivities of the composites were explained in microcosmic field. The phonon mean free path determines the thermal conductivity, and it can be significantly affected by temperature and the contact surface area. The leaks, thermal storage and release properties of pure paraffin and paraffin/kaolin composites were investigated and the composites presented good thermal stabilities.
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高影响因子
Waste and Biomass Valorization
·
2016
·Vol. 9
·期 1
·95-101
·
IF 0.915
Ning Liangmin,Liao Shengyun,Sun Yongfa,Yu Linhao,Tong Xinli
Abstract The catalytic synthesis of 2,5-diformylfuran (DFF) from 5-hydroxymethylfurfural (HMF) attracts extensive attention in the research of biomass conversion. However, it is a challenge to achieve high conversion of HMF under mild conditions with a heterogeneous catalyst, which can be easily separated and recycled. Herein, we report a novel cobalt-based catalyst (Co x O y -N@TiO 2 ) for the oxidation of HMF to DFF with 30 % aqueous tert -butyl hydroperoxide as the oxidant. A series of Co-based catalysts were prepared by a typical impregnation method, and detected by XRD, TEM and FT-IR techniques. Based on the experimental results of catalytic test, it is found that a 91 % conversion of HMF and 40 % selectivity of DFF was obtained with the Co x O y -N@TiO 2 catalyst at 80 °C within 5 h. In addition, the Co x O y -N@TiO 2 can be recycled up to five times without significant loss of activity. Graphical Abstract The efficient oxidation of 5-hydroxymethyl furfural, a biomass-derived platform compound, to produce 2,5-diformylfuran is achieved using Co x O y -N@TiO 2 catalyst under mild conditions.
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高影响因子
RSC Advances
·
2016
·Vol. 6
·期 102
·100079-100089
·
IF 3.289
Kaiyue Zhang,Zijian Cui,Guangyu Xing,Yaqing Feng,Shuxian Meng
Dye-sensitized solar cells (DSSCs) fabricated with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite gel electrolytes containing variable amounts of modified kaolin were studied in this work. The kaolin was modified with silane coupling agent γ-aminopropyltriethoxysilane (KH550), and the modified kaolin (M-KL) was characterized by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The results of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) indicated that the crystallinity of polymer membranes decreased with the addition of M-KL nanoparticles. The ionic conductivity and diffusion coefficient (I3−) of polymer gel electrolytes (PGEs) reached optimum values of 9.452 × 10−3 S cm−1 and 10.37 × 10−6 cm2 s−1 for 3 wt% M-KL, respectively, which contributed to higher short-circuit current density (Jsc) and photoelectric conversion efficiency (η) of the corresponding DSSCs. The optimum level of η reached 7.48% under the illumination of 100 mW cm−2, an increase of 16.3% compared with the DSSC without M-KL.
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