Immobilisation of a luminescent material on an electrode surface is well known to substantially modulate its photophysical and electrochemical properties. Here a positively charged ruthenium metal complex ([Ru(bpy) 3 ] 2+ ) is immobilised on all electrode surface by ion paring with a sulfonated conducting polymer poly(2-methoxyaniline-5-sulfonic acid), (PMAS). Significantly, our study reveals that the electron transport between the ruthenium metal centres can be greatly enhanced due to the interaction with the conducting polymer when both are surface confined. Charge transfer diffusion rates in the present system are an order of magnitude faster than those found where the metal centre is immobilised within a non-conducting polymeric matrix. Electron transport appears to be mediated through the PMAS conjugated structure, contrasting with the electron hopping process typically observed in non-conducting metallopolymers. This increased regeneration rate causes the ruthenium-based electrochemiluminescence (ECL) efficiency to be increased. The impact of these observations on the ECL detection of low concentrations of disease biomarkers is discussed.
A waste material known as palm oil empty fruit bunch (EFB) is used as a source of cellulose for the development of polymeric materials for the removal of metal ions from industrial wastewater. A poly(acrylonitrile)-grafted palm cellulose copolymer was synthesized by a conventional free radical initiating process followed by synthesis of a poly(amidoxime) ligand by oximation reaction. The resulting products were characterized by FT-IR, FE-SEM, EDX, TGA, DSC, and XPS. The poly(amidoxime) ligand was used to coordinate with and extract a series of transition metal ions from water samples. The binding capacity (qe) of the ligand with the metal ions such as copper, iron, cobalt, nickel, and lead were 260, 210, 168, 172, and 272 mg g−1 , respectively at pH 6. The adsorption process followed the pseudo-first-order kinetic model (R2 > 0.99) and as well as the Freundlich isotherm model (R2 > 0.99) indicating the occurrence of a multi-layer adsorption process in the amidoxime ligand adsorbent. Results from reusability studies show that the ligand can be recycled for at least 10 cycles without any significant losses to its initial adsorption capacity. The synthesized polymeric ligand was shown to absorb heavy metals from electroplating wastewater with up to 95% efficiency.
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