Co-reporter:Rong Peng, Xiaonong Chen, Raja Ghosh
Separation and Purification Technology 2017 Volume 174() pp:561-569
Publication Date(Web):1 March 2017
DOI:10.1016/j.seppur.2016.10.037
•Fabrication of graphene oxide-cotton fiber composite adsorbent.•Covalent grafting of graphene oxide on cotton fiber.•Purification of polyphenols using aqueous solvent system.•Purification of polyphenol ellagic acid from pomegranate peel extract.•Almost total removal of protein and sugars impurities.We discuss the synthesis of graphene oxide-cotton fiber composite adsorbent and its use for purification of polyphenols. Graphene oxide was grafted onto cotton fiber through amidation and epoxy ring-opening. Polyphenols have shown significant promise in various therapeutic applications. The current study examines the feasibility of purifying polyphenols from pomegranate peel extract (e.g. ellagic acid) by using graphene oxide-cotton fiber adsorbent. Using ultrapure water as binding phase and sodium hydroxide solution as eluting phase, 72% of the sugars and almost the entire amount of protein impurities present in the feed material could be removed. The ellagic acid concentration in the purified sample was 3.6 times of that in the feed solution while the total polyphenols concentration increased from 48% to 76%. The polyphenol binding capacity of the adsorbent was 51 mg/g while the overall recovery for polyphenols was approximately 73%.
Co-reporter:Qi-jia-yu Wu;Rui Wang;Ying Zhou;Ya-qin Huang
Chinese Journal of Polymer Science 2015 Volume 33( Issue 7) pp:1048-1057
Publication Date(Web):2015 July
DOI:10.1007/s10118-015-1655-6
Thermal and salt dual stimuli-responsive filter-paper-based membranes were prepared by UV-induced grafting of NIPAM-based polymers on paper surface. The grafting ratio could be controlled by monomer concentration during grafting polymerization. The results from pressure drop measurement of the mobile phase flowed cross the membrane demonstrate that an appropriate grafting ratio would be 8%–10%. Protein adsorption on the membrane through hydrophobic interaction could be promoted by increasing temperature and lyotropic salt concentration. The effect of grafted polymer structure on protein binding performance was studied. Filter paper grafted with NIPAM-based branched copolymer consisting of hydrophobic monomer moieties shows ten times higher protein binding capacity than that of the original filter paper. The separation of plasma proteins using the dual stimuli-responsive membrane was examined to demonstrate feasible application for hydrophobic interaction chromatographic separation of proteins.
Co-reporter:Qijiayu Wu, Rui Wang, Xiaonong Chen, Raja Ghosh
Journal of Membrane Science 2014 Volume 471() pp:56-64
Publication Date(Web):1 December 2014
DOI:10.1016/j.memsci.2014.07.072
•Temperature-responsive membrane chromatography.•Paper-polymer composite membrane with two-step transition behavior.•Protein binding and release by temperature manipulation.•Hydrophobic interaction chromatography using lyotropic salt-free mobile phase.•Feasibility demonstrated by purifying monoclonal antibody.Butyl-acrylate (BA) containing branched poly-(N-isopropyl acrylamide) or PNIPAM copolymer was grafted on filter paper to prepare composite membrane for carrying out temperature-responsive hydrophobic interaction membrane chromatography (HIMC) of proteins. The copolymer demonstrated two-step phase transition behavior due to the presence of BA and PNIPAM, making the changeover from hydrophilic to hydrophobic state more tunable. The feasibility of using the temperature-responsive membrane was demonstrated by controlling human immunoglobulin G (hIgG) binding and release using temperature change. Higher temperature promoted protein binding and lower temperature favored protein release in this process, which was carried out using lyotropic salt-free mobile phase. The purification of monoclonal antibody (mAb) hIgG1-CD4 from simulated CHO cell culture supernatant was carried out to demonstrate practical application for the novel temperature-responsive membrane.
Co-reporter:Li Cao, Dunfan Su, Zhiqiang Su, and Xiaonong Chen
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 6) pp:2308-2317
Publication Date(Web):January 23, 2014
DOI:10.1021/ie403746p
A novel multiwalled carbon nanotube/polypropylene (CNT/PP) conductive fibrous membrane with fiber diameter of 1–3 μm was fabricated by melt electrospinning. To improve the dispersibility of CNT and enhance the spinnability of PP fibers, CNTs were first mixed with small amounts of paraffin liquid (PL) and then melt-blended with PP for melt electrospinning. The morphology of fibrous membranes and the orientation of CNTs in PP fibers were observed via scanning and transmission electron microscopy (SEM and TEM). The effect of PL and CNTs on crystallization behavior of PP was studied by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Tensile test and impedance analysis were performed to investigate the mechanical and electrical properties of the fibrous membranes. The results indicated that CNT has a distinct nucleating effect on PP, and the addition of PL can improve the spinnability of the CNT/PP compound remarkably. This novel conductive fibrous membrane fabricated by melt electrospinning exhibits improved tensile strength and modulus, good electric conductivity, and enhanced dielectric constant and hydrophobicity.
Co-reporter:Zhe Huang, Hongyuan Shao, Bicheng Huang, Chengming Li, Yaqin Huang and Xiaonong Chen
RSC Advances 2014 vol. 4(Issue 36) pp:18737-18743
Publication Date(Web):07 Apr 2014
DOI:10.1039/C4RA00756E
The adsorption of methylene blue (MB) from aquatic systems by the fish-scale-based hierarchical lamellar porous carbon (FHLC) was investigated. In this paper, the FHLC was used as an alternative adsorbent to replace the Norit CGP, a commercial activated carbon, and showed an overall fast and pH-dependent MB adsorption. The effect of contact time, pH and concentration on MB adsorption was investigated. It was found that the adsorption behaviours of FHLC and CGP could be described by a monolayer Langmuir type isotherm. The kinetic data followed the pseudo second-order kinetic model for both activated carbons as the linear correlation coefficients were all above 0.9999. Thermodynamic analyses indicated that the adsorption was an endothermic and spontaneous physisorption process. The maximum Langmuir adsorption capacity of the FHLC was 555.55 mg g−1 at pH = 7.07 and 1050.72 mg g−1 at pH = 11.00 while that of the CGP was 432.90 mg g−1 at pH = 7.07 and 649.35 mg g−1 at pH = 11.00, respectively. The adsorption capacity of the FHLC was much better than that of the CGP at different pH values. Our study shows that fish-scale-based carbon could be used as a high-performance and cost-effective adsorbent to remove MB in aqueous solution in the wastewater treatment.
Co-reporter:Li Cao;Dun-fan Su;Zhi-qiang Su 苏志强
Chinese Journal of Polymer Science 2014 Volume 32( Issue 9) pp:1167-1175
Publication Date(Web):2014 September
DOI:10.1007/s10118-014-1465-2
β-nucleated isotactic polypropylene (iPP) fibers with diameters less than 5 μm were prepared through melt electrospinning. The effects of electrospinning process and rare earth β-nucleating agent (WBG) on the crystal structure of iPP fibers were investigated. The results indicate that the addition of WBG can improve the fluidity of iPP melt remarkably and help the formation of fine fibers with thinner diameter, while the electrostatic force applied on the iPP melt is not favorable for the formation of β-crystal in iPP fibers. In addition, the morphology and crystalline structure of WBG/iPP electrospun fibers depended on the content of WBG. Both the crystallinity and the percentage of β-crystal form of WBG/iPP electrospun fibers increase with the rise of the content of nucleating agent, which endows the prepared electrospun fibers excellent mechanical properties. The β-nucleated iPP electrospun fibrous membranes prepared in this study can be used for protective clothing material, filtration media, reinforcement for composites and tissue engineering scaffolds.
Co-reporter:Weiyi Lv, Yaseen El-Hebshi, Bo Li, Yuzheng Xia, Riwei Xu, Xiaonong Chen
Polymer Testing 2013 Volume 32(Issue 2) pp:353-358
Publication Date(Web):April 2013
DOI:10.1016/j.polymertesting.2012.11.017
Brominated butyl rubber (BIIR) was crosslinked through an esterification reaction using the sodium salt of dicyclopentadiene dicarboxylic acid (DCPDCA) as crosslinking agent. The crosslinked BIIR could de-crosslink upon heating and re-crosslink upon cooling due to Diels-Alder type reversible de-dimerization/re-dimerization of dicyclopentadiene moieties in the rubber networks. Torque measurement of the crosslinked rubber was conducted at various temperatures using a typical curemeter to investigate the thermo-reversibility. It was revealed that proper temperature for thermal processing of the crosslinked BIIR would be around 174 °C, at which the crosslinked polymer exhibits good flowability and is not too high to induce unexpected side reactions. The torque measurement was also carried out to investigate the efficiency of antioxidant on retarding the loss of the thermo-reversibility of the crosslinked polymer during heating-cooling cycles. It was found that addition of antioxidant 2246 [2,2′-methylenebis(6-tert-butyl-4-methylphenol)] into BIIR could significantly improve the thermo-reversibility of DCPDCA crosslinked BIIR. Torque measurement provides a convenient and sensitive method to understand the thermal behavior of reversible covalent crosslinked polymer.
Co-reporter:Li Cao;Mu Dong;Anyang Zhang;Yong Liu;Weimin Yang;Zhiqiang Su
Polymer Engineering & Science 2013 Volume 53( Issue 12) pp:2674-2682
Publication Date(Web):
DOI:10.1002/pen.23515
Ultrafine fibers or fiber web is an attractive material for its high aspect ratio or porous structure which is welcomed in various applications. In this study, ultrafine fibers (5–10 μm) of styrene–acrylonitrile (SAN) copolymer/isotactic polypropylene (iPP) blends were produced by melt electrospinning, SAN acted as a polymeric nucleating agent (PNA) in iPP fibers. Wide-angle X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and polarized optical microscopy were used to investigate the morphologies and the crystal structures of SAN/iPP electrospun fibers. The results showed that SAN/iPP melt formed microfibers with different morphologies and crystallinities through electrostatic stretching. The morphological distribution of SAN in iPP fibers depended on the SAN content, and the distribution influenced its nucleating activity and the final crystal structure of SAN/iPP electrospun fibers. After annealing treatment, the molecular chains of iPP in the confined SAN/iPP microfibers disorientated and rearranged, leading to the formation of a mixture of α- and γ-crystal forms. The relative amount of the γ-crystal form depended on PNA's concentration, annealing temperature and annealing time. Melt electrospun iPP fibers prepared in this study were collected as fiber webs that can be used for protective clothing material, filtration media, reinforcement for composites, and so on. POLYM. ENG. SCI., 53:2674–2682, 2013. © 2013 Society of Plastics Engineers
Co-reporter:Zhiqiang Su;Qing Li;Li Cao
Journal of Applied Polymer Science 2011 Volume 121( Issue 4) pp:2072-2077
Publication Date(Web):
DOI:10.1002/app.33825
Abstract
High-resolution cryogenic Fourier transform infrared spectroscopy (FTIR) was used to measure the variation of the unit cell volume of ethylene-octene copolymers (EG) in this study. It was found that both the comonomer content and thermal history have great influence on the crystal lattice structure of ethylene polymers. With the increase of the octene content, the unit cell volume of EG copolymers expand, and quenching treatment favors the increase of distance between two molecular chains in orthorhombic crystals and causes more crystal lattice deformation. Compared with traditional wide-angle X-ray diffraction method, high-resolution cryogenic FTIR spectroscopy, as a powerful technique for measuring the changes of crystal lattice structures of polyethylene and ethylene copolymers, can provide more accurate information on the characterization of the changes of crystal lattice structures of semicrystalline polymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Zhiqiang Su, Liang Zhang, Jiaohong Zhao, Xiaonong Chen
Polymer 2011 Volume 52(Issue 4) pp:1084-1091
Publication Date(Web):17 February 2011
DOI:10.1016/j.polymer.2011.01.012
In the current research, the complexation of bovine serum albumin (BSA) with poly(N-isopropylacrylamide) (PNIPAM) is studied in an aqueous system (pH 7) which contains NaCl as its supporting salt, and based on the electric charge conservation law a mathematical model used to quantitatively characterize the complexation between proteins and neutral polymers is established. This model, which is set up on the assumptions that there exists a dynamic equilibrium of absorption and desorption among free proteins, complexes and free polymers in the aqueous complex system and the complexation sizes of proteins with neutral water soluble polymers are not uniform, better reveals the actual state of complexation. By means of dynamic light scattering (DLS), fluorescence spectrophotometer and zeta potential analyzer, all necessary parameters of the mathematical model have been acquired accurately without destroying the dynamic equilibrium of the aqueous complex system. The calculated results demonstrate that, with the rise of mixing ratio (rmixing, molar ratio of PNIPAM to BSA), both the average number of bound BSA per PNIPAM (nb) and the diameters of complexes (Rh) decrease gradually, while the zeta potential (ζ) and the concentration of free PNIPAM ([PNIPAM]free) increase. In addition, the average number of PNIPAM in the complexes (φ) and the molecular weight of the complexes (Mw) can also be calculated by this mathematical model. The changing pattern of Mw with rmixing is in accordance with the results of static light scattering (SLS). This analysis method, which interprets the interaction between neutral polymers and proteins in an aqueous system, is a new way to calculate the complex parameters and study the complexation mechanism between proteins and polymers.
