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INDONESIA
Science and Technology Indonesia
Published by Universitas Sriwijaya
ISSN : 25804405     EISSN : 25804391     DOI : -
Core Subject : Science, Social, Engineering,
Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Environmental Science Materials Science & Nanotechnology Physics
An international Peer-review journal in the field of science and technology published by The Indonesian Science and Technology Society. Science and Technology Indonesia is a member of Crossref with DOI prefix number: 10.26554/sti. Science and Technology Indonesia publishes quarterly (January, April, July, October). Science and Technology Indonesia is an international scholarly journal on the field of science and technology aimed to publish a high-quality scientific paper including original research papers, reviews, short communication, and technical notes. This journal welcomes the submission of articles that covers a typical subject of natural science and technology such as: > Chemistry > Biology > Physics > Marine Science > Pharmacy > Chemical Engineering > Environmental Science and Engineering > Computational Engineering > Biotechnology Journal Commencement: October 2016
Arjuna Subject : -
Articles 581 Documents
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The Synthesis of CH₃NH₃PbI₃₋ₓBrₓ under Uncontrolled Humidity for Perovskite Solar Cell Application Kusumawardani, Cahyorini; Ikhsan, Jaslin; Budiasih, Kun Sri; Herlambang Nugroho; Widowati, Asri
Science and Technology Indonesia Vol. 11 No. 1 (2026): January
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.1.298-310

Abstract

CH₃NH₃PbI₃₋ₓBrₓ perovskite films were successfully synthesized under uncontrolled humidity using a two-step spin-coating method followed by Ostwald ripening (OR) treatment. Bromide incorporation into CH₃NH₃PbI₃ was achieved by diluting the pre-formed CH₃NH₃PbI₃ films with CH₃NH₃Br (MABr) solutions at various concentrations. X-ray diffraction (XRD) analysis confirmed the formation of a tetragonal perovskite phase with reduced lattice parameters as the bromide concentration increased, indicating successful substitution of I⁻ by Br⁻ ions. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) characterization showed that moderate bromide incorporation (30–40 mg/mL) produced dense and uniform grains with homogeneous halide distribution, whereas excessive MABr resulted in non-uniform morphology and halide segregation, particularly under humid conditions. Optical analysis revealed a gradual blue shift of the absorption edge, consistent with band gap widening due to lattice contraction. Photovoltaic performance measurements demonstrated that higher MABr concentrations led to decreased current density and fill factor, attributed to excessive bromide content and defect formation. These findings indicate that controlled bromide incorporation via Ostwald ripening using an MABr concentration of 20 mg/mL effectively enhances the structural quality, film stability, and photovoltaic performance of CH₃NH₃PbI₃₋ₓBrₓ perovskite solar cells under humid environments.
The Influence of Milling on the Structural and Morphological Properties of Waste-Based Active Carbon from Rubber Seeds Using High Energy Milling (HEM) Method Arsyad, Fitri Suryani; Aprilianda; Aulia; Akmal Johan; Ihsan Alfikro; Amiruddin Supu; Ahmad, Nur; Andrivo Rusydi
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.621-631

Abstract

The high-energy milling (HEM) synthesis method has produced activated carbon powder from rubber ore shell waste. The activated carbon was prepared using a chemical method with activation temperatures varying between 400, 500, and 600°C. Temperature optimization resulted in activated carbon with a maximum carbon content at 600°C. The activated carbon was then milled for various times: 0, 30, 60, and 90 minutes. The crystallinity and surface morphology of the samples were then confirmed using an X-ray diffractometer (XRD) and scanning electron microscope (SEM) characterization. Based on the XRD graph, the percentage of structural regularity, or degree of crystallinity, of the activated carbon tended to decrease from 18.17% without milling treatment to 17.52% at 30 minutes of milling, 17.45% at 60 minutes of milling, and 17.35% at 90 minutes of milling. SEM images also show a decrease in the average pore diameter from approximately 0.45 µm to 0.20 µm with a more homogeneous intraparticle morphology structure when the milling time is increased from 30 minutes to 90 minutes. This study demonstrates the potential of rubber seed shell waste for processing into activated carbon. The HEM method can significantly reduce the grain size of activated carbon and increase its surface area and reactivity, making it more effective in applications as an adsorbent and filter.
Utilization of Diatom Frustule Waste from Navicula sp. TAD as Photoelectrode Material for Enhancing the Efficiency of Dye-Sensitized Solar Cells (DSSC) Telussa, Ivonne; Tehubijuluw, Hellna; Lilipaly, Eka Rahmat Mahayani Anthonia Putera; Malle, Dominggus; Amarduan, Riona Magdalena
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.632-642

Abstract

Navicula sp. TAD is a microalga with silica-based cell walls, offering potential to improve photon interaction in dye-sensitized solar cells (DSSCs). This study combined Navicula sp. TAD frustules with TiO2 to fabricate DSSC working electrodes. The objectives were to isolate and characterize the frustules, optimize the TiO2–frustule ratio, and evaluate photoelectric performance. The workflow consisted of cultivating Navicula sp., isolating pigments and frustules, fabricating solar cells with varied electrode compositions, and performing photoelectric testing under a solar simulator. Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Scanning Electron Microscope (SEM) analysis confirmed that the frustules possess nanoporous surfaces and exhibit Si–O–Si and Si–OH functional groups. Electrodes incorporating TiO2–frustule blends showed compact pore networks, along with additional functional groups. Performance screening across compositions identified an optimal TiO2–frustule ratio of 40:60, which delivered an efficiency of 10.51%, a short-circuit current density of 0.673 A, an open-circuit voltage of 301.8 mV, and a fill factor of 0.32. These findings indicate that frustule-enabled light management and surface chemistry can jointly enhance dye loading and charge collection in DSSC photoanodes relative to TiO2 alone.
Effect of pH on Brazilin Extraction from Sappanwood (Caesalpinia sappan L.) and Its Impact on the Efficiency of Natural Dye-Sensitized Solar Cells (DSSCs) Al Hafidl, Achmad Naufal; Nita Kusumawati; Pirim Setiarso; Samik, Samik; Maria Monica Sianita Basukiwardojo; Khofifatul Rahmawati
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.378-388

Abstract

Dye-sensitized solar cells (DSSCs) are a sustainable photovoltaic technology for addressing the global energy crisis through the conversion of solar energy using photosensitive dyes. This study aims to investigate the effect of pH variation during extraction on the optical, electrochemical, and photovoltaic characteristics of brazilin dye from sappanwood (Caesalpinia sappan L.) for DSSC applications. Brazilian extraction was performed using Microwave-Assisted Extraction (MAE) with pH conditioning from 2 to 12. UV-Vis spectroscopy showed an increase in light absorbance at 400–800 nm. The pH 8 dye exhibited a maximum absorption peak at 444.59 nm due to the formation of a quinoidal base through partial deprotonation of the hydroxyl (-OH) group. FTIR characterization confirmed the chemical structure of the dye with characteristic absorption spectra of broad bands at 3000–3500 cm-1 for the phenolic hydroxyl group and peaks at 2800–3000 cm-1 for aromatic C-H stretching vibrations, as well as aromatic C=C and C=O stretching vibrations at 1600–1400 cm-1. Energy band gap analysis revealed that the dye at pH 2–12 has an energy gap range of 0.1788–0.5355 eV. Optimizing the extraction pH revealed that pH 8 yields the most effective dye performance, resulting in a peak DSSC efficiency of 2.17%, a minimal charge transfer resistance of 100 Ω, and the narrowest energy bandgap at 0.1788 eV. Weakly basic conditions enhance dye molecule conjugation, strengthen bonding with TiO2, and optimize the overall charge transfer process. The research findings confirm the potential of optimizing natural dye extraction conditions as a strategy to enhance DSSC efficiency in a sustainable and environmentally friendly manner.
ZnO-SiO₂ Nanocomposite: Synthesis, Characterization, and Application of Corrosion Inhibition Alam Q. AL-Hussin; Taleb Bader, Ali; Al-Gubury, Hazim Yahya
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.538-550

Abstract

Herein, we are reporting the synthesis of zinc oxide (ZnO), silicon dioxide (SiO2), and a binary nanocomposite ZnO-SiO2 by the co-precipitation method. The materials were comprehensively characterized, such as via Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), UV–Vis spectroscopy, and nitrogen adsorption–desorption (BET) measurements before their application. The presence of typical Zn-O and Si-O vibrations characteristic of ZnO was confirmed by FTIR spectra, whereas the hexagonal morphology of ZnO crystals, spherical SiO2, and agglomerated ZnO-SiO2 nanostructures were confirmed by SEM images. XRD measurements showed the crystallinity of the as-obtained nanostructures and the average crystallite sizes of 37.78 nm for ZnO, 48.01 nm for SiO2, and 34.09 nm for composite ZnO-SiO2 as determined by the Scherrer equation. The synthesized ZnO, SiO2, and ZnO-SiO2 nanoparticles were then evaluated on the basis of their inhibitive abilities toward corrosion processes in mild steel coupons exposed to 1M HCl estimated by potentiodynamic polarization. All the studied binary composites emerged as having the strongest inhibitory potential, with the ZnO-SiO2 nanocomposite root system experience showing the most powerful inhibition potential, reducing the corrosion current density i-corr to 36.1 µA cm-2 and reaching 93% inhibition efficiency. These results demonstrate that the future of using co-precipitation-based synthesis lies in the ability to obtain tunable nanostructure composites with desirable physicochemical properties and efficient corrosion inhibition in acidic media
Tuning Magnetic Behavior of La₁₋ₓSrₓFeO₃ (x = 0.1–0.5) via Sr Doping: From Antiferromagnetism to Ferromagnetism Ramlan; Naibaho, Marzuki; Ginting, Masno
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.515-523

Abstract

Strontium-substituted LaFeO₃ compounds with the chemical formula La₁₋ₓSrₓFeO₃ (x = 0.1–0.5) were successfully prepared via the solid-state reaction technique by partially replacing La at the A-site. Structural analysis was carried out using X-ray diffraction (XRD), while surface morphology and elemental composition were investigated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS). The magnetic behavior of the samples was evaluated using a vibrating sample magnetometer (VSM). XRD patterns confirmed that all synthesized compositions crystallized in a single-phase LaFeO₃ structure without detectable impurity phases. The dominant diffraction peak corresponded to the (121) crystallographic plane, indicating an orthorhombic structure with the Pnma space group (No. 62). SEM observations revealed irregular particle morphologies with a broad particle size distribution. EDS analysis verified the successful incorporation of Sr into the LaFeO₃ lattice, as evidenced by the presence of La, Fe, O, and Sr elements in all doped compositions (x = 0.1–0.5). Magnetic measurements showed that the La₀.₉Sr₀.₁FeO₃ sample exhibited the best magnetic performance, with a saturation magnetization (Mₛ) of 0.393 T and a coercive field (Hc) of 2661 Oe. The introduction of Sr induced a transition in magnetic behavior from antiferromagnetic to ferromagnetic ordering. Overall, these results demonstrate that La₁₋ₓSrₓFeO₃ materials are promising candidates for electromagnetic wave absorption applications.
Valorization of Palm Empty Fruit Bunch-Derived K₂CO₃ Catalyst: Structural Analysis and Application in Biodiesel Production Arita, Susila; Fitriyanti, Reno; Komariah, Leily Nurul; Hadiah, Fitri
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.420-435

Abstract

This study investigates the synthesis and performance of a K2CO3 catalyst derived from oil palm empty fruit bunch (EFB) ash for sustainable biodiesel production. X-ray Diffraction (XRD) revealed a dominant K2CO3 crystalline phase, while X-ray Fluorescence (XRF) confirmed a high potassium content (>40%). Despite its low surface area (0.11 m2/g), the catalyst demonstrated high transesterification activity, achieving an optimal biodiesel yield of 85.89% with 3 grams of catalyst. Its high thermal stability, strong base sites, and macroporous structure all contributed to enhanced catalytic efficiency. Sustainability and techno-economic assessments indicate the catalyst’s potential to reduce production costs, utilize biomass waste, and lower greenhouse gas emissions. Thus, the EFB ash-based K2CO3 catalyst shows significant promise for supporting environmentally friendly biodiesel production and contributing to the transition to a green economy and renewable energy.
Heterocyclic Azo Compounds, Synthesis, Characterization, Evaluation as Antimicrobial, and Theoretical Study Mohammed, Mohammed K.; Al-Jaber, Afrah A.; Al-Asadi, Rafid H.; Dhaef, Hawraa K.
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.489-501

Abstract

Five azo compounds, including N-(3-hydroxyphenyl) maleimide, were synthesized and characterized using FT-IR, 1H-NMR, 13C-NMR, and mass spectroscopy. The compounds were evaluated for antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa using the disk diffusion method. The screening results showed that the azo compounds tested were effective against the bacteria tested, particularly Staphylococcus aureus. The geometry optimization of the molecular structures and the energy calculations for compounds 1-5 were performed using the density functional approach. Molecular docking was conducted to examine the interaction of the synthesized compound 1 with two bacterial receptors and one viral receptor (neuraminidase). It was found that they would target the PDB:4CJN protein, for which the compound yielded the lowest binding energy.
Relation Between Randic and Harmonic Energies of Commuting Graph for Dihedral Groups Romdhini, Mamika Ujianita; Nawawi, Athirah
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.481-488

Abstract

Consider a finite group G with center Z(G). This work examines the commuting graph $\Gamma_G$, a graph constructed from a group $G$ whose vertices correspond precisely to the noncentral elements of the group, that is, all elements in $G$ except those belonging to its center $Z(G)$. The graph is defined on the vertex set $G\backslash Z(G)$, where two distinct vertices vp and vq are joined by an edge precisely when they commute, that is, whenever vp vq=vq vp. The number of vertices adjacent to vp is denoted as dvp, which is the degree of vp. The Randic and harmonic matrices of $\Gamma_G$ are defined as square matrices in which $(p,q)-$th entry are $\frac{1}{\sqrt{d_{v_p} \cdot d_{v_q}} }$ and $\frac{2}{d_{v_p}+d_{v_q} }$ if $v_p$ and $v_q$ are adjacents, respectively; otherwise, it is zero. Randic energy is the sum of the absolute eigenvalues of the Randic matrix whereas harmonic energy is the sum of the absolute eigenvalues of the harmonic matrix. In this paper, we compare the Randic and harmonic energies of the commuting graph for non-abelian dihedral group of order 2n, D2n.
Optimization of Hydrolyzed Pumpkin (Cucurbita Moschata) Starch as Natural Superdisintegrant in Promethazine HCl Sublingual Tablets Winarti, Lina; Asrofi, Muhammad; Lubis, Maralodia Almira; Lestari, Tirtawati Putri; Sari, Lusia Oktora Ruma Kumala; Irawan, Eka Deddy; Febryanto, Hery Diar; Afthoni, Muhammad Hilmi; Eryani, Mikhania Christiningtyas
Science and Technology Indonesia Vol. 11 No. 2 (2026): April
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2026.11.2.502-514

Abstract

Acid hydrolysis of pumpkin starch is a feasible strategy for developing novel pharmaceutical excipients, particularly natural superdisintegrants for sublingual and orally disintegrating tablet formulations. Given the requirement for extremely rapid tablet disintegration in sublingual dosage forms, selecting an efficient disintegrant is a critical formulation parameter. However, native pumpkin starch exhibits limited disintegration efficiency and generally requires high concentrations, which may adversely affect tablet hardness and friability. This study aimed to optimize the acid hydrolysis process of pumpkin starch and to evaluate the performance of the optimized hydrolyzed starch as a natural superdisintegrant in Promethazine HCl sublingual tablets. A factorial design was used to examine the impact of varying hydrolysis durations (3-9 days) and hydrochloric acid concentration (5-9%) on the physicochemical characteristics of the modified starch. The optimized hydrolyzed starch demonstrated a near-neutral pH (5.17 ± 0.03), acceptable moisture content (LOD 10.20 ± 0.44%), and excellent flow properties, as indicated by a low angle of repose (23.96°) and Carr’s index (9.99%). Scanning electron microscopy revealed increased surface irregularity and porosity, while FTIR analysis indicated enhanced exposure of hydroxyl groups, consistent with partial depolymerization of the starch polymer. The amylose content increased to 35.17%, accompanied by improved water uptake and swelling capacity. The effective pore radius (25.03 ± 0.35 µm) and swelling index (70.25 ± 0.57) were markedly higher than those of native pumpkin starch (12.27 µm and 44.30 ± 0.85, respectively), although slightly lower than crospovidone (27.65 µm and 99.97 ± 0.13). Incorporation of the hydrolyzed starch into Promethazine HCl sublingual tablets resulted in formulations with adequate mechanical strength (hardness 3.35 ± 0.05 kg), low friability (0.53 ± 0.04%), rapid disintegration (49.18 ± 0.75 s), and high drug release (96.79 ± 0.13%). These performances were comparable to those of crospovidone and superior to formulations containing native pumpkin starch. The improved tablet characteristics were primarily attributed to enhanced porosity and swelling capacity induced by acid hydrolysis. Overall, optimized hydrolyzed pumpkin starch demonstrates considerable potential as a sustainable, biodegradable, and cost-effective natural superdisintegrant for fast-disintegrating pharmaceutical tablet formulations.

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