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All Journal Jurnal Fisika Unand
Astuti Astuti
Departemen Fisika, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Andalas
Earth & Planetary Sciences Electrical & Electronics Engineering Energy Materials Science & Nanotechnology Physics

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Efektivitas Perubahan Fase Material KCl/H2O sebagai Sistem Pendingin Ikan Laut Iqbal Alief; Sri Rahayu Alfitri Usna; Astuti Astuti; Sri Oktamuliani
Jurnal Fisika Unand Vol 13 No 1 (2024)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.13.1.8-14.2024

Abstract

This study aims to determine the effectiveness of phase change material (PCM) KCl/H2Oas a fish cooling system. KCl/H2Ois a eutectic PCM of hydrate salts with a melting temperature of -10.7 °Cand an enthalpy of 273 kJ/kg. The samples tested were Kuwe marine fish with a mass of 1 kg (4 heads). The variation in fish mass to KCl/H2Ois 1:0.5, 1:1, 1:2, and 1:3. The process of changing the temperature of the fish cooling system every time is measured using the DS18B20 temperature sensor. Based on the study's results, KCl/H2Ois effective in reducing fish temperature by -0.22 °C/minute.The use of 2 kg KCl/H2O is effective in maintaining fish temperature in the temperature range of0 to 5 °C for 20 hours, and the use of 3 kg KCl/H2Ois good in maintaining fish temperature in the lower temperature range of -5 to 0 °C for 16 hours. In terms of economy, the cost of handling the fish cooling process using KCl/H2Ois six times greater than conventional cooling, so this system is less recommended.
Pengaruh Waktu Hidrotermal Terhadap Sifat Optik Nanokomposit Fe3O4@CQD (Carbon Quantum Dots) Putri Azima Rafsanjani; Astuti Astuti
Jurnal Fisika Unand Vol 14 No 6 (2025)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.14.6.561-568.2025

Abstract

This study aims to synthesize Fe₃O₄@CQD nanocomposites using a hydrothermal method with time variations to study their effects on the structural and optical properties of the material. Fe₃O₄ nanoparticles were obtained through a coprecipitation method, while CQDs were synthesized from the extract of sappan wood (Caesalpinia sappan L.) which is natural, environmentally friendly, and has the potential as a fluorescent material. The results of XRD characterization showed that Fe₃O₄ has a crystal size of 22.476 nm, while the addition of CQDs increased the crystal size of the nanocomposite. FTIR analysis confirmed the presence of typical functional groups such as Fe–O, O–H, C–H, and C=O indicating the presence of CQDs in Fe₃O₄. UV-Vis test shows that Fe₃O₄@CQD has an absorption peak in the wavelength range of 300-700 nm, while the fluorescence test shows that the emission intensity increaseswith increasing hydrothermal time, with the emission peak at a wavelength of 600–650 nm.
Co-Authors Iqbal Alief Putri Azima Rafsanjani Sri Oktamuliani Usna, Sri Rahayu Alfitri