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Effectiveness of Gold Extraction with Thiourea Solution from Gold Rocks in Mount Tumpang Pitu Pasanggaran Banyuwangi Andarini, Novita; Ramadhani, Ferlia Suci; Haryati, Tanti; Suwardiyanto
Indonesian Chimica Letters Vol. 3 No. 2 (2024)
Publisher : Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Jember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/icl.v3i2.4107

Abstract

This research aims to determine the effect of adding an oxidizing solution in the gold extraction process using thiourea solution. The oxidizing agent used in thiourea leaching solution is FeCl3. Variations of additional volume of oxidizing solution are 0 mL, 10 mL, 20 mL, 30 mL, and 40 mL. Based on the results obtained, the addition of 30 mL oxidant FeCl3 can get optimal results. The thiourea leaching solution can extract gold as much as 46.7%.
Two-Stage Hydrothermal Synthesis of TiO₂ Nanotubes with Variation of Precursor Type for Diazinon Photodegradation Haryati, Tanti; Assiddiq, Mustafid A’yun; Suwardiyanto, Suwardiyanto; Andarini, Novita; Sulistiyo, Yudi Aris
Jurnal Kimia Sains dan Aplikasi Vol 28, No 4 (2025): Volume 28 Issue 4 Year 2025
Publisher : Chemistry Department, Faculty of Sciences and Mathematics, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jksa.28.4.195-199

Abstract

TiO2 is commonly used as a photocatalyst for the photodegradation of harmful chemical compounds, such as diazinon. Its photocatalytic properties can be enhanced by fabricating it into nanotubes. TiO2 nanotube (TNTs) has a large surface area with good photon absorption and electron transport. This study aims to determine the effect of precursor type on the morphology, crystal structure, and photocatalytic activity of the resulting TNTs against diazinon. TNTs synthesis was carried out through a two-stage hydrothermal method using TiO2 micro powder precursors in anatase and rutile phases. The photocatalytic activity of TNTs was tested against diazinon photodegradation. The morphology of TNTs resulting from the first and second hydrothermal processes was fiber-shaped for anatase TNP precursor (TNPa) and rutile TNP precursor (TNPr). TEM characterization showed that the TNT particles were tubular with an outer diameter of 2.27-10.92 nm and an inner diameter of 1.10-4.2 nm. Some impurities, such as sodium titanate and hydrogen titanate, still appear in the diffraction patterns of TNTa and TNTr. The TNTr photocatalyst underwent crystal phase transformation into anatase, which was compared with the JCPDS data. The percentage of degradation for TNTa photocatalyst is slightly greater than TNTr, reaching 85.9% and 82.4%, respectively.
Synthesis of TiO2-Activated Carbon from Coffee Dregs by Hydrothermal Method for Photodegradation of Diazinon Haryati, Tanti; Zakaria, Helmy Ahmad; Sutisna, Sutisna; Suwardiyanto, Suwardiyanto; Sulistiyo, Yudi Aris; Andarini, Novita
Molekul Vol 20 No 1 (2025)
Publisher : Universitas Jenderal Soedirman

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20884/1.jm.2025.20.1.13714

Abstract

ABSTRACT. The photocatalytic activity of TiO₂ can be enhanced by binding it to materials with high adsorption capacity. The synthesis began with the mixture of 5 mL TTIP, 30 mL ethanol, and H₂O 30 mL stirred for 1 hour. Activated carbon made from coffee grounds in varying amounts (5 g, 10 g, and 15 g) was then added to the TTIP solution, and the mixture was stirred for 2 hours. The mixture was then placed in an autoclave, heated at 180°C for 12 hours, dried, and then calcined at 500°C for 3 hours. SEM morphological analysis showed that TiO₂ particles were attached to the surface of the activated carbon, which was further confirmed by EDX data showing the presence of Ti and O elements in the synthesized material. Furthermore, crystallinity and gap analyses demonstrated that the material was exclusively in the anatase phase. The largest surface area, 286.10 m²/g, was observed on titanium dioxide-activated carbon/10 (TiO₂-AC/10), exhibiting a mesoporous structure and microporous features. Photocatalytic tests for diazinon degradation demonstrated that TiO₂-AC/10 exhibited the most significant photocatalytic activity of 65.18%. The composite material's degradation capability diminished by 9-13% from the initial to the third cycle. The residual titanium elements within the composite material maintained stability, suggesting the integrity and durability of TiO₂ particles affixed to the surface of activated carbon. Keywords: TiO2-AC, Coffee Dregs, Diazinon, Photocatalysis, Reusability
Extraction of Aluminium (Al) Metal from Coal Fly Ash of PLTU-Paiton with NaOH Solvent Puspa, Aranca Nindya; Haryati, Tanti; Andarini, Novita
Indonesian Chimica Letters Vol. 2 No. 2 (2023)
Publisher : Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Jember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/icl.v2i2.5616

Abstract

Fly ash, a solid waste product from the coal combustion process at the Paiton PLTU, contains 14.52-23.78% alumina (Al2O3). This can be extracted using NaOH for further utilization. The Al(OH)3 precipitate was obtained using a 4 M HCl solution with pH variations of 6 and 6.5. Meanwhile, Al metal was obtained using a reduction temperature variation of 600-700°C with an interval of 50°C using Mg metal reductant for 2.5 hours. The aluminum metal obtained was subjected to qualitative analysis by UV-Vis spectrophotometer and quantitative analysis by XRF and AAS. The Al(OH)3 precipitate obtained at a pH of 6.001 weighed 1.581 grams, with a yield of 61.83%, while at a pH of 6.500 it weighed 1.688 grams, with a yield of 66.02%. Applying a specific reagent for Al metal, alizarin, to qualitative analysis resulted in a maximum wavelength of 495 nm. A quantitative analysis was conducted utilizing the atomic absorption spectrophotometer (AAS) at a wavelength of 309.3 nm. The alumina content in fly ash was determined to be 14.52%, with an Al metal yield of 8.67% at a pH of 6 and 9.01% at a pH of 6.5, at an optimal reduction temperature of 650°C.