Influence Of Activated Charcoal On The Structural And Morphological Characteristics Of Ceramic Based On Silicon Oxycarbide (sioc): A Promising Approach To Obtain A New Electrochemical Sensing Platform

This study deals with the preparation of ceramic materials based on silicon oxycarbide (SiOC), by pyrolysis of polymeric precursors consisting of poly(methylsiloxane) (PMS) and divinylbenzene (DVB), with or without activated charcoal (AC) as additional carbon source. The precursors were obtained by hydrosilylation reaction catalyzed by Pt(0)-complex at 80:20 and 20:80 (PMS:DVB) molar ratios, containing or not 3 wt.% AC. SiOC-based materials were obtained by pyrolysis at 1000 and 1500 degrees C, under argon atmosphere, and characterized by FT-IR, Raman, Si-29 MAS NMR, XRD, elemental analysis, SEM and HRTEM techniques. The presence of AC in PMS-rich ceramic produced carbon long nanowires, and possibly SiC nanowires. The increase of the temperature induced the phase segregation, with the predominance of SiO2 and/or SiC phases, besides having influence on the crystallization of beta-sic and organization of segregated carbon phase (C-free), with the formation of multiwall carbon nanotubes (MWCNT). The ceramics containing AC were tested as a new electrochemical sensing platform for the detection of acetaminophen by cyclic voltammetry. Higher peak current and lower over potential for acetaminophen, as compared with glassy carbon electrode, were observed by using the ceramic obtained at 1500 degrees C containing MWCNT as electrodic material, which clearly indicates the great electrocatalytic effect of material. (C) 2016 Elsevier B.V. All rights reserved.175334

<b>Evaluation of DMIT [4,5-Dimercapto-1,3-Dithyol-2-Thionate] as chelating agent in a cloud point extraction procedure for Pb2+ determination in water samples</b> - doi: 10.4025/actascitechnol.v35i2.18076

<p class="aresumo">The present study proposes a new method for cloud point preconcentration of Pb²⁺ ions based on complex formed with [4,5-dimercapto-1,3-dithyol-2-thionate] and posterior determination by flame atomic absorption spectrometry (FAAS). The preconcentration of Pb²⁺ was carried at pH 5.0 under following conditions: time and temperature of batch at 15 min. and 70^oC, respectively, 0.1% (v/v) Triton X-114, 0.003 mol L^-1 acetate/acetic acid buffer solution, 1.0 x 10^-5 mol L^-1 DMIT and 0.5% (m/v) NaCl. Under the best analytical conditions the method provided a limit of detection of 2.85 mg L^-1 by preconcentrating 10.0 mL of sample and calibration curve ranging from 0 up to 650 mg L^-1 (r = 0.99945). The applicability of proposed method for Pb²⁺ determination in natural waters without interferences was checked through addition/recovery tests.</p> <p class="akeyword"> </p