This work demonstrates a simple and one-step synthesis of polythiophene/gold nanoparticles (PT/Au) nanocomposite thin films, through a liquid-liquid (L/L) interfacial polymerization route. Starting from an aqueous solution of tetrachloroauric acid (acting both as metallic gold source and oxidizing agent to start the oxidative polymerization of thiophene), and a solution of thiophene in n-hexane, a biphasic L/L system was originated. In the following, the interface acted as a meeting-point for the reactants, and the polymerization reaction took place, leading to self-assembled PT/Au film between the two immiscible liquids. These films were easily deposited over different substrates (glass, silicon, plastics) and characterized through different techniques. The influence of both the reactants ratio and the reaction time on the structure and morphology of the films were evaluated. The films obtained with a shorter reaction time exhibited spherical gold nanoparticles (around 3 nm diameter) homogeneously dispersed into a polymeric matrix. The increase of both the reaction time and the thiophene/gold precursor ratio led to agglomerated and anisotropic gold structures wrapped by a thin layer of polythiophene. Overall, PT/Au films are transparent, homogeneous, stable, flexible and presented reversible electrochromic properties, which make them suitable for application in different systems and devices, as demonstrated here for electrochromic application.

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A B S T R A C TAdsorption experiments were carried out using waste Mexerica mandarin "Citrus nobilis" peel as a new biosorbent to adsorb Cu(II), Cd(II), and Pb(II) ions from aqueous solutions at room temperature. To achieve the best adsorption conditions, the influences of pH and contact time were investigated. The isotherms of adsorption were fitted to the Langmuir and Freundlich equations. Based on the experimental data the adsorption order was Pb(II)>Cd(II) >Cu(II) (in mg g À1 ) on the new biosorbent. This quick adsorption process reached the equilibrium before 20 min, with maximum adsorptions at pH 5.0. Kinetic studies were carried out using the pseudo-first-order and pseudo-second-order models. Thermodynamic aspects of the adsorption process were investigated. The new biosorbent was used in columns for the removal of Cu, Cd, and Pb ions of the samples of industrial effluent and its efficiency and regeneration potential were studied.

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