Polymer of Intrinsic Microporosity (PIM-1) Enhances Hydrogen Peroxide Production at Gii-Sens Graphene Foam Electrodes

3D-graphene foam electrodes (Gii-Sens) immersed in a phosphate buffer solution of pH 7 are shown to generate hydrogen peroxide at a significantly faster rate in the presence of a nanoparticulate polymer of intrinsic microporosity (PIM-1). The effect is demonstrated to be associated at least in part with oxygen binding into PIM-1 under triphasic conditions. The release of the oxygen at the electrode|solution interface quadruples H 2O 2 production. Generator–collector experiments are performed with a graphene foam disk generator and a platinum disk electrode collector to allow in situ detection of hydrogen peroxide and oxygen.</p

Determination of uronic acids in sugarcane bagasse by anion-exchange chromatography using an electrode modified with copper nanoparticles

Uronic, D-glucuronic and D-galacturonic acids are found in lignocellulosic materials and are known to be used in the food industry and chemical industries. They are present in the fibrous structure of sugarcane bagasse, where they are incapable of being detected owing to the lack of absorption of the chromophore and fluorophore groups in their molecular structure, thus restricting their detection by traditional spectrophotometric methods. The detection is only possible by means of derivatization. In this light, a modified detector with copper nanoparticles by potentiostatic electrodeposition was developed. D-Galacturonic and D-glucuronic acids are oxidized irreversibly at potentials of 0.45 and 0.48 V vs. Ag/AgCl, respectively, in cyclic voltammetry. This modified electrode was used in chromatography with pulsed amperometric detection in wall-jet cells. An anion exchange column, CarboPac PA10, was used for the separation of uronic acids under isocratic conditions, with the mobile phase containing 0.1 M NaOH plus 280 mM CH3COONa. The separation of the acids was found to be complete within 15 minutes. The detection limit was 5.8 107 and 7.3 107 mol1 and the amperometric sensitivity was 3.6 1.8 106 and 1.9 1.0 106 mA l mol1 for D-galacturonic and D-glucuronic acids respectively. The aforementioned method developed was then applied to real samples of hydrolyzate bagasse. The amount of acid found in this sample was 15.8 0.5 g kg1 and 12.5 0.5 g kg1 for D-galacturonic and D-glucuronic acids respectively. The results demonstrate that the proposed method can be used for the detection of these acids without the need for derivatization, given its merits of exerting no interference, having considerable accuracy and shorter run time. 1. IFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES