Electrochemical studies in detecting persistent organic pollutants (POPs) have attracted a lot of interest from researchers, especially the carbon paste electrode (CPE). The research objectives were to determine the electrochemical characteristics of TiO2/Ag-Li on the CPE in the system Fe2+/Fe3+ and determine the fipronil in solution. TiO2/Ag-Li preparation was carried out by using the sol-gel method. Electrochemical performance of CPE was applied by cyclic voltammetry. The system developed was a reversible redox reaction and have peaks Ipa 110 µA and Ipc 105 µA. We also found that the composition of the best modifier addition to CPE was using TiO2/Ag-Li with a mass of 0.005 g. The optimum scan rate for the measurement of the fipronil test solution was obtained at 0.2 V/s with an Ipa value of 15 µA and an Epa value of 0.40 V. Based on the plot between the root scan rate and the oxidation current of the solution containing fipronil, the obtained R2 value was 0.9806. This research provides the development of modifier CPE material with the well electrochemically performance and considered as a very effective monitored system for the environment contaminated by POPs waste.
Kurangnya sumber belajar terutama prasarana praktikum menyebabkan praktikum di sekolah tidak terlaksana. Pokok bahasan materi asam basa yang seharusnya berpraktikum tidak dapat diterapkan karena keterbatasan indikator. Hasil pengamatan di lapangan menunjukkan siswa tidak bisa membedakan larutan asam dan basa karena tidak mendapat paktikum. Guru mata pelajaran kimia di beberapa SMA di Kabupatem Donggala tidak melaksanakan praktikum pada materi asam basa karena belum pernah menggunakan bahan alam seperti bunga sebagai pembuat bahan kertas pH. Olehnya diperlukan peningkatan pemahaman kepada guru mengenai konsep asam basa dan bahan alam yang dapat digunakan sebagai indikator alami pengganti indikator sintetik. Kegiatan pengabdian ini diikuti oleh 10 peserta yang terdiri dari guru-guru kimia anggota MGMP kimia Kabupaten Donggala. Kegiatan pengabdian dilaksanakan dengan pemahaman konsep asam basa dan pemanfaatan bahan alam sebagai indikator alami serta melakukan demontrasi dan penbimbingan pembuatan kertas pH dari bahan alam(bunga). Kegiatan ini memberi tambahan pengetahuan bagi guru-guru dalam pemanfaatan bahan alam sebagai bahan pengganti indikator sintetik dalam praktikum materi asam basa sehingga diharapkan kualitas pembelajaran meningkat.
Moringa seed oil has many long-chain fatty acid contents that very potential transformed become fatty acid methyl ester or biodiesel. CaO material that was obtained from calcinating of chicken eggshells can be used as a heterogeneous catalyst at biodiesel production from Moringa seed oil. The purpose of this research was to determine the reaction time that produced biodiesel with the highest mass fraction of fatty acid methyl esters and also to determine the characteristics of biodiesel. Biodiesel was made through a transesterification reaction by using CaO catalyst at a mole ratio of oil: methanol of 1:6 for 1, 2, 3, and 4 hours. Transesterification reaction for 2 hours resulted in a methyl ester mass fraction of 82.69%. GC-MS analysis result has shown that methyl oleate had the highest concentration of 86.56% at a retention time of 37.62 minutes. The characteristics of biodiesel including the acid number of 0.09 mg KOH/g, saponification number of 356.4 mg KOH/g, iodine number of 0.635 g iod/100g, cloud point of 13°C, pour point of 20°C, and cetane number of 61.45.
Infectious disease is one of sources of high morbidity and mortality caused by bacteria. Artocarpus plant is biosource to discover compounds with interesting bioactivites. The objective of this study is to find antibacterial compound from nature by extraction, fractionation, identification, and antibacterial test of secondary metabolite from dichloromethane extract of Artocarpus dasyphylla tree bark. The dichloromethane extract was fractionated repeatedly using various chromatographic techniques. The secondary metabolite was identified of its molecular structure based on UV-Vis, IR, NMR spectral data and confirmed by comparation with the reference. The secondary metabolite was known as catechin or 5,7,3’,4’-tetrahydroxyflavan-3β-ol. Antibacterial testing of cathecin against Escherechia coli and Staphylococcus aureus showed a low antibacterial activity.
Gold tailings are waste generated from gold mining activities and contain minerals and rare-earth metals (REM) that are much needed in current technological developments. This research was conducted to determine the REM content contained in Poboya gold tailings, through the destruction process using sulfuric acid and precipitation using ammonium hydroxide. The results were showed that the level of REM contained in Poboya gold tailings was 6-7%. REM oxide content analysis performed with Scanning Electron Microscopy - Energy Dispersive X-Ray Spectroscopy (SEM-EDS) obtained 6 types of REM with the main REM levels namely Terbium (Tb): 77-80% dan Lanthanum (La): 13%, as well as other rare-earth metals with smaller amounts of Europium (Eu): 4-5%, Cerium (Ce): 2%, Neodymium (Nd): 0.02% and Gadolinium (Gd): 0.02%. Poboya gold waste can be used by the community as a source of REM and used in various industries. Keywords: Gold tailings, rare earth metals (REM), destruction, precipitation
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