Preparation and characterization of hydroquinone based polyoxalate and its application in the removal of heavy metals from water

Hydroquinone based polyoxalate was synthesized from oxalyl chloride and hydroquinone. The polymer was characterized with FTIR, 1H-NMR, 13C-NMR, PXRD, SEM and thermal analysis. The chelation behaviour of the polymer towards Pb(II), Cd(II), and Hg(II) in aqueous solutions was studied by batch technique as a function of contact time and pH. The polymer showed high metal uptake toward Pb(II) and Cd(II) and moderate metal uptake toward Hg(II). The adsorption capacity was not affected by the pH of solution. The adsorption data were fitted with second order kinetic model and the isotherms models of Langmuir and Freundlich. Thermodynamics measurements showed that sorption process was spontaneous. Furthermore, the chelating polymer was loaded with metal ions using fixed bed column. For regenerating the loaded polymer, different eluting agents include HNO3, H2SO4, and EDTA was investigated. The highest recovery of metal ions was achieved using HNO3, indicating that desorption process was governed by the solubility factor and cation exchange mechanism.Â

Synthesis and Characterization of Polycarbonates by Melt Phase Interchange Reactions of Alkylene and Arylene Diacetates with Alkylene and Arylene Diphenyl Dicarbonates

This work presents a new synthetic approach to aromatic and aliphatic polycarbonates by melt polycondensation of bisphenol A diacetates with alkylene- and arylenediphenyl dicarbonates. The diphenyl dicarbonates were prepared from phenyl chloroformate and the corresponding dihydroxy compounds. The process involved a precondensation step under a slow stream of dry argon with the elimination of phenyl acetate, followed by melt polycondensation at high temperature and under vacuum. The potential of this reaction is demonstrated by the successful synthesis of a series of aromatic-aromatic and aromatic-aliphatic polycarbonates having inherent viscosities from 0.19 to 0.43 dL/g. Thus low to intermediate molecular mass polymers were obtained. The 13C-NMR spectra of the carbon of the carbonate group showed that the formed polycarbonates contain partial random sequence distribution of monomer residues in their chains. The polycarbonates were characterized by inherent viscosity, FTIR, 1H-NMR and 13C-NMR spectroscopy. The glass transition temperatures, measured by DSC, of the polycarbonates were in the range 13–108 ºC. The thermogravimetric curves of showed that these polymers have good thermal stability up to 250 ºC. The present approach may open the door for novel polycarbonates containing other organic functional groups

Preparation and characterization of poly(Bisphenol A-Phthalate) and its metal removal behavior toward Pb(II), Cu(II), and Cd(II) ions

ABSTRACTThe polymer poly(BPA-phthalate) (BPA-PHTH) was synthesized from BPA and phthaloyl dichloride by using interfacial condensation polymerization. The prepared polymer was characterized using (FTIR,1H-NMR, 13C-NMR, DSC, TGA, SEM, and polymer solution viscosity. The characterization by 1H-NMR, 13C-NMR, and FTIR proved the suggested structure. The DSC shows that the polymer is not linear, while the TGA shows that it is thermally stable up to 350°C. SEM showed solid surface filled with pores. The polymer uptake behavior towards Pb(II), Cd(II), and Cu(II) ions was studied by the batch equilibrium technique as a function of pH and contact time. The metal-ion uptake by the polymer reached at pH = 6 a maximum of 92.59, 65.79, and 72.46 for Pb(II), Cd(II), and Cu(II) ions, respectively. The metal ion uptake properties of the polymer show fitting for Langmuir, Freundlich, and (D-R) isotherm equations. The experimental data fit to both the Langmuir and the Freundlich models (R2 > 0.99). Column experiments were used to determine the loading capacity and study the desorption of metal ions. The metal-bound polymer was regenerated by treatment with 0.1 M HNO3 for Pb(II) and Cd(II), while 0.5 M EDTA for Cu(II). Therefore, it may be employed for the removal of heavy metal pollutants in environmental and industrial applications

Fabrication of porous bioceramics for bone tissue applications using luffa cylindrical fibres (LCF) as template

Three-dimensionally ordered macroporous biomaterials containing hydroxyapatite were synthesized using natural luffa cylindrical fibres (with diameter of 100–400 µm) as templates. The preliminary evaluation of this novel method for production of porous bioceramics showed promising potential applications in bone tissue engineering. The produced bioceramics were subjected to microstructural, physical, mechanical, and in vitro characterisation. Mercury intrusion porosimetry, supported by SEM analysis, showed the presence of bimodal porosity (smaller pores with diameters of 10 to 30 µm and cylindrical macropores with diameters from 100 to 400 µm) and 60% of the interconnected porosity. These porous calcium phosphate ceramics proved to be bioactive and exhibited mechanical properties comparable to those of natural spongy bones with compressive strength up to 3 MPa and elastic modulus in compression around 0.05 GPa. In vitro characterization of the porous ceramics showed cells attaching to the apatite crystals that make up the scaffold matrix. Cell adhesion resulted in elongated and highly stretched cells within the macropores with focal adhesion points on the scaffolds. Moreover, the cells adhered to the calcium phosphate cement (CPC) and developed cytoplasmic extensions as shown by SEM imagery. Their proliferation in the scaffolds in culture demonstrates that the scaffold architecture is suitable for Mesenchymal stem cells seeding and growth