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Sainteknol : Jurnal Sains dan Teknologi
Published by Universitas Negeri Semarang
ISSN : -     EISSN : 25273604     DOI : https://doi.org/10.15294/sainteknol
Core Subject : Education,
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Sainteknol published a scientific paper on the results of research and studies in the field of science and technology. Published biannually in June and December contained the writings lifted from the results of research and critical-analysis study in science and technology.
Arjuna Subject : Umum - Umum
Articles 3 Documents
 1 
Search results for , issue "Vol. 23 No. 2 (2025): December 2025" : 3 Documents clear
Density–Porosity Interplay in Epoxy‑Based Syntactic Foams Reinforced with K15 Glass‑Silica Microballoons Hidyus, Sofi Alifia; Budiwirawan, Agung; Musyono, Ari Dwi Nur Indriawan; Setiadi, Rizky; Bunyamin, Bunyamin
Sainteknol : Jurnal Sains dan Teknologi Vol. 23 No. 2 (2025): December 2025
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/sainteknol.v23i2.23886

Abstract

Syntactic foam is a lightweight, high‑strength composite consisting of a polymer matrix filled with hollow microspheres (microballoons). This study examines how the volume fraction of glass‑clad silica microballoons K15 (10–50 vol %) affects the density, porosity, and void distribution of epoxy‑bonded syntactic foams. Specimens were molded in accordance with ASTM D790, conditioned for 48 h (23 ± 2 °C; 50  ±  5 % RH), and their density was measured by the pycnometric method specified in ASTM D792. Porosity was calculated theoretically and validated by SEM–EDS imaging of fracture cross‑sections. Results show a linear decrease in density from 1.15 g cm⁻³ (0 vol %) to 0.63 g cm⁻³ (50 vol %), while porosity rises exponentially from 2.7 % to 18.4 %. Morphological analysis confirms a homogeneous microballoon dispersion up to 30 vol %, but agglomeration and interbinder voids appear above 40 vol %, leading to uncontrolled porosity. A strong negative correlation (R² = 0.96) is observed between density and effective porosity. A 30 vol % K15 loading is identified as the optimum, achieving a 28 % density reduction without a significant porosity spike. These findings provide a basis for designing sandwich cores and amphibious flotation structures that require high strength‑to‑weight ratios.
Recycling End-of-Life (EoL) Reverse Osmosis (RO) Membranes into Ultrafiltration Membranes using Potassium Permanganate (KMnO4) for Aquaculture Water Filtration Putri, Raden Rara Dewi Artanti; Triwibowo, Bayu; Prasetiawan, Haniif; Salwa, Dian Fatimatus; Fauziah, Whilda; Pradana, Daffa Zamiira; Aldiansar , Divifan Armyko
Sainteknol : Jurnal Sains dan Teknologi Vol. 23 No. 2 (2025): December 2025
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/sainteknol.v23i2.32896

Abstract

Sustainable and economical management of aquaculture water is a significant challenge in the fisheries industry. This study aims to convert End-of-Life (EoL) Reverse Osmosis (RO) membranes into Ultrafiltration (UF) membranes using a potassium permanganate (KMnO4) solution as an oxidizing agent to enhance the efficiency of aquaculture water filtration. The conversion process involves immersing the used RO membranes in a 4,5% w/v KMnO4 solution for 3 days at room temperature. Prior to conversion, the membranes were cleaned using a 0,1% w/v Sodium Dodecyl Sulfate (SDS) solution and 0,05 M Ethylenediaminetetraacetic Acid (EDTA) to remove organic and inorganic contaminants. The results showed an increase in water flux from 20 L/m²•h to 50 L/m²•h after conversion. The analysis of aquaculture water quality after filtration using the converted UF membranes showed a significant reduction in Biological Oxygen Demand (BOD) from 5,547 mg/L to 3,817 mg/L, representing 31,2% reduction, and Chemical Oxygen Demand (COD) from 29,91 mg/L to 24,22 mg/L, representing 19% reduction. The membranes were highly effective in removing coliforms, achieving a 100% reduction from 180 MPN/100mL to 0 MPN/100mL. The values of DO and TDS decreased by only about 2%, salinity values remained unchanged, while total ammonia increased. The conversion process increases efficiency filtration, reduces operational costs, and decreases membrane waste. 
Synergistic Enhancement of Lignocellulosic Biomass Saccharification via Ultrasound-Assisted Pretreatment with Magnetic Fe₃O₄ Hanif Ardhiansyah; Astrilia Damayanti; Bahlawan, Zuhriyan Ash Shiddieqy; Serlia Fitri Sadan; Nurul Khusna; Karenina Hakim
Sainteknol : Jurnal Sains dan Teknologi Vol. 23 No. 2 (2025): December 2025
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/sainteknol.v23i2.41061

Abstract

The recalcitrant structure of lignocellulosic biomass necessitates efficient pretreatment strategies to enhance enzymatic saccharification for biofuel production. This study investigates a synergistic approach combining ultrasound irradiation with magnetic Fe₃O₄ for pretreating rice straw. A 2² factorial experimental design was employed to systematically evaluate the individual and combined effects of ultrasound (300 W, 30 min) and Fe₃O₄ addition (1.5 wt%). The combined treatment exhibited a pronounced synergistic effect, achieving 68.3% delignification and reducing the crystallinity index from 52.4% to 31.2%. These structural modifications resulted in a saccharification yield of 72.5%, which was significantly higher than the theoretical additive yield of 48.7% (raw: 18.5%, Fe₃O₄-only: 26.0%, ultrasound-only: 41.2%). SEM observations revealed extensive surface erosion, pore formation, and microfibril exposure after the combined pretreatment, while FTIR analysis confirmed substantial lignin removal. Furthermore, magnetic Fe₃O₄ demonstrated excellent magnetic separability, with a recovery efficiency higher than 95%, and maintained pretreatment performance over five reuse cycles with < 8% reduction in efficacy. Overall, this work presents a green, efficient, and economically promising pretreatment strategy based on synergistic ultrasound–magnetic Fe₃O₄ interactions, offering an effective pathway for enhancing lignocellulosic biomass saccharification and supporting the development of sustainable biorefinery processes.

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