Keberadaan timbal di lingkungan yang disebabkan oleh polusi dapat masuk dalam darah. Menurut Center for Disease Control and Prevention (CDC) batas ambang timbal dalam darah yaitu 4.8×10-7 M. Apabila melebihi batas tersebut maka dapat menyebabkan keracunan bahkan kematian. Dengan demikian diperlukan kontrol darah secara berkala dengan metode relatif mudah. Pada penelitian ini dikembangkan sensor timbal dalam darah berbasis elektroda selektif ion timbal yang dimodifikasi dengan membran kitosan dan garam timbal sulfida (PbS) sebagai bahan aktif. Penelitian ini bertujuan menentukan kondisi optimum dalam pengembangan sensor ion timbal. Konsentrasi bahan aktif (PbS) yang ditambahkan dalam larutan kitosan yaitu 0,5% sampai 2,5% (b/v). Ketebalan membran yang digunakan yaitu 15 µm; 25 µm; 40 µm; 75 µm. Elektroda diuji pada pH larutan 2; 3; 4 dan 5 dengan konsentrasi larutan standar Pb(NO3)2 10-8 M hingga 10-1 M. Kinerja optimum elektroda diperoleh pada konsentrasi PbS 1,5% dengan ketebalan membran 15 µm dan pH larutan 4. Bilangan Nernst yang diperoleh yaitu 24,35 mV/dekade dengan kisaran konsentrasi 0,032 ppm hingga 0,322 ppm dan konsentrasi larutan terkecil yang digunakan yaitu 0,032 ppm.
Hydrodeoxygenation (HDO) is applied in fuel processing technology to convert bio-oils to green diesel with metal-based catalysts. The major challenges to this process are feedstock, catalyst preparation, and the production of oxygen-free diesel fuel. In this study, we aimed to synthesize Ni catalysts supported on silica-zirconia and alumina-zirconia binary oxides and evaluated their catalytic activity for waste cooking oil (WCO) hydrodeoxygenation to green diesel. Ni/Al2O3-ZrO2 and Ni/SiO2-ZrO2 were synthesized by wet-impregnation and hydrodeoxygenation of WCO was done using a modified batch reactor. The catalysts were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS), and N2 isotherm adsorption-desorption analysis. Gas chromatography - mass spectrometry (GC-MS) analysis showed the formation of hydrocarbon framework n-C15 generated from the use of Ni/Al2O3-ZrO2 with the selectivity of 68.97% after a 2 h reaction. Prolonged reaction into 4 h, decreased the selectivity to 58.69%. Ni/SiO2-ZrO2 catalyst at 2 h showed selectivity of 55.39% to n-C15. Conversely, it was observed that the reaction for 4 h increased selectivity to 65.13%. Overall, Ni/Al2O3-ZrO2 and Ni/SiO2-ZrO2 catalysts produced oxygen-free green diesel range (n-C14-C18) enriched with n-C15 hydrocarbon. Reaction time influenced the selectivity to n-C15 hydrocarbon. Both catalysts showed promising hydrodeoxygenation activity via the hydrodecarboxylation pathway. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
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