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The current research work deals with the synthesis of a novel composite material of carboxylic graphene oxide‐carboxymethyl chitosan (COOH‐GO‐CMC) composite by ultrasound and microwave‐assisted processes. The composite was characterized by Fourier Transform Infra‐red spectroscopy, X‐ray Powder Diffraction, Raman Spectroscopy, Scanning Electron Microscopy, and X‐ray Photoelectron Spectroscopy. The synthesized composite was used to remove heavy toxic metal ions (HTMIs) such as uranium (U6+), lead (Pb2+), chromium (Cr6+), and cadmium (Cd2+) ions from aqueous solutions. The HTMIs removal study was carried out to verify the effects of pH, contact time, amount of adsorbent dose, initial concentration, and temperature. The linear and nonlinear Langmuir and Freundlich adsorption isotherms were fitted to the data of removal studies, and it was observed that the linear Langmuir adsorption isotherm (R2 > 0.99) was the best‐fitted model. The maximum adsorption capacities of COOH‐GO‐CMC were found to be 74.62, 416.66, 76.92, and 53.47 mg g−1 for U6+, Pb2+, Cr6+, and Cd2+ ions, respectively. The kinetics studies, including four types of models (linear and nonlinear pseudo‐first‐order, linear and nonlinear pseudo‐second‐order, Intraparticle diffusion, and Elovich kinetic models), were tested, and the results showed that the linear pseudo‐second‐order kinetics model (R2 > 0.99) was the best‐fitted model. The thermodynamic studies reveal that the adsorption of HTMIs is a spontaneous (ΔG < 0) and exothermic (ΔH < 0 and ΔS > 0) process in nature. [ABSTRACT FROM AUTHOR]

In the present study, salicylaldimine zinc complex (Zn- HMBED) was synthesized and its reactivity for the ring-opening polymerization ( ROP) of lactide was studied. The zinc complex was prepared by the reaction of zinc solution with one molar equivalent of salicylaldimine Schiff base ligand in methanol under a nitrogen atmosphere. Further, the complex was characterized by various spectroscopic methods, which showed tetrahedral geometry. X-ray diffraction studies were used for the structure determination of the Schiff base. It was observed that the zinc complex is highly active towards the ROP of lactide. The rate of polymerization is heavily dependent on the initiator used. The zinc complex allows controlled ROP as revealed by the linear relationship between the percentage conversion and the number-average molecular weight. Finally, a mechanism for the ROP of lactide is proposed by use of the above zinc complex. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Poly(etheretherketone) PEEK, is a versatile polymer having a wide range of applications in different fields because of its good mechanical properties, thermal stability, toughness, etc. However, nowadays its application as a fuel cell membrane is an emerging research area. Thus, suitable selection and modification of PEEK is necessary. The synthesis of the sample membrane and design of the fuel cell should be properly carried out to meet the market need. This chapter will introduce different applications of PEEK and modified PEEK with particular emphasis on fuel cells. Basically, sulfonated PEEK (SPPEK) has been observed to be more advantageous for fuel cell applications because of its good proton conductivity. The various synthesis methods, sample preparation methods and evaluation of fuel cells will be presented in this article. [ABSTRACT FROM AUTHOR]

In the present work, the -ONNO- tetradentate Schiff base ligand N, N′-bis (2-hydroxy-3-methoxybenzaldehyde) propylenediamine, [HMBPD] was synthesized. Further, complexation of this ligand with copper [HMBPD-Cu] was carried out and their reactivity for the ring-opening polymerization (ROP) of lactide (LA) has been studied. This monomeric copper complex is prepared by the reactions of copper solution with one molar equivalent of HMBPD Schiff-base ligand in ethanol under nitrogen atmosphere. This copper complex has been characterized by different spectroscopic methods, which showed square planner geometry. The copper complex is highly active towards ROP of LA. The rate of polymerization is heavily dependent on the initiator used. The copper complex allows controlled ring-opening polymerization as shown by the linear relationship between the percentage conversion and the number-average molecular weight. On the basis of literature reports, a mechanism for ROP of lactide has been proposed. [ABSTRACT FROM AUTHOR]

A series of heterobimetallic titanium(IV) complexes [LTi(O(i)Pr)(mu-O(i)Pr)(2)Li(THF)(2)], [LTi(O(i)Pr)(mu-O(i)Pr)(2)Na(THF)(2)], [LTi(mu-O(i)Pr)(2)Zn(O(i)Pr)(2)], and [LTi(mu-O(i)Pr)(2)Mg(O(i)Pr)(2)] (where L = bidentate bisphenol ligands) have been synthesized and characterized including a structural determination of [L(1)Ti(mu(2)-O(i)Pr)(2)(O(i)Pr)Li(THF)(2)] (1a). These complexes were investigated for their utility in the ring-opening polymerization (ROP) of l-lactide (LA). Polymerization activities have been shown to correlate with the electronic properties of the substituent within the bisphenol ligand. In contrast to monometallic titanium initiator 1e, all the heterobimetallic titanium initiators (Ti-Li, Ti-Na, Ti-Zn, and Ti-Mg) show enhanced catalytic activity toward ring-opening polymerization (ROP) of l-LA. In addition, the use of electron-donating methoxy or methylphenylsulfonyl functional ligands reveals the highest activity. The bisphenol bimetallic complexes give rise to controlled ring-opening polymerization, as shown by the linear relationship between the percentage conversion and the number-average molecular weight. The polymerization kinetics using 2c as an initiator were also studied, and the experimental results indicate that the reaction rate is first-order with respect to both monomer and catalyst concentration with a polymerization rate constant, k = 81.64 M(-1) min(-1).