Helium: Journal of Science and Applied Chemistry

Green Synthesis and Formation of Silica Nanoparticles Based on Natural Spondias mombin Leaf Extract for Renewable Energy Materials

2025-12-24T05:00:56+00:00

Silica is an abundantly available material, with applications including renewable energy materials (fuel cells). Silica has been produced using natural materials (green synthesis) to form smaller and more stable particles, primarily due to the influence of secondary metabolites such as those contained in the leaf of Spondias mombin, a species of flowering plants from Lannea coromandelica (Houtt.) Merr and the family Anacardiaceae. The characteristics of silica nanoparticles obtained by green synthesis using the Spondias mombin leaf in a water fraction at 0,6 % were identified using XRD, FTIR, PSA, TGA, SEM, and TEM. Based on the XRD pattern and SEM/TEM images, the nanoparticle is amorphous and has a particle size of 20-30 nm, smaller than that of its precursor, which is 37.6 nm. There are Si-OH and Si-O-Si groups in the FTIR spectrum as an indication of the interaction between silica nanoparticles and secondary metabolites, and the zeta potential based on PSA is -45.9 mV. This indicates that silica nanoparticles have good stability and are supported by high thermal stability based on the results of the TGA analysis. This is correlated with its use as a material composite in renewable energy (fuel cells).

Characterization of Lipolytic Activity from Nyamplung (Calophyllum inophyllum L.) Seeds

2026-01-20T05:41:09+00:00

Lipases are biocatalysts widely utilized in industrial and biotechnological processes due to their ability to catalyze the hydrolysis and synthesis of ester bonds. The search for novel lipase sources from plant materials continues to attract attention, particularly for sustainable and eco-friendly enzyme production. This study aims to isolate and characterize lipase from Nyamplung (Calophyllum inophyllum L.) seeds. The enzyme was extracted from germinated seeds and subjected to activity assays under varying temperature, pH, and germination length conditions. The highest lipase activity was obtained at 35 °C and pH 7.5, with an activity of 0.92 U/mL. The maximum activity was observed after 15 days of imbibition, reaching 1.06 U/mL. Protein characterization through SDS-PAGE revealed multiple bands with molecular weights of ~28, ~21 and ~19 kDa, indicating the presence of isoenzymes or subunit structures. These results suggest that Nyamplung seed lipase exhibits suitable catalytic properties for biotechnological applications. The enzyme’s moderate temperature and neutral pH optima make it a potential candidate for use in food and oleochemical industries.

Tuning Surface Wettability and Porosity of ZnO/Geopolymer Composite Membranes from Coal Fly Ash through H₂O₂ as Pore-Forming Agent

2026-04-13T05:45:47+00:00

The development of geopolymer membranes from industrial by-products offers a sustainable approach for water purification. In this study, ZnO/geopolymer membranes were prepared from coal fly ash, with hydrogen peroxide (H₂O₂) used as a pore-forming agent to regulate porosity and surface wettability. The influence of H₂O₂ concentration (0-6 wt%) on membrane physicochemical properties was systematically evaluated. FTIR analysis confirmed the formation of sodium aluminosilicate hydrate (N-A-S-H) gel and the incorporation of ZnO through the presence of Si-O-Zn and Zn-O bands. SEM images showed that increasing H₂O₂concentration changed the initially dense structure into a rougher and more porous surface due to oxygen bubble generation during curing. ZnO addition enhanced surface roughness and functionality, while H₂O₂improved pore connectivity. The water contact angle decreased from 21.63° in the pristine geopolymer to below 15° in the membrane with 6 wt% H₂O₂, indicating greater hydrophilicity. Porosity also increased from about 10% to 50%. These results demonstrate that ZnO incorporation combined with controlled H₂O₂addition effectively tailors membrane wettability and pore structure, making the composite promising for sustainable water filtration.

A Comparative Photocatalytic Activity of ZnO and TiO₂ toward Rhodamine B Degradation under UV Irradiation

2025-02-13T09:03:08+00:00

The rapid growth of Indonesia’s textile sector has increased waste output. Textile production generally uses synthetic dyes, such as rhodamine B. These manufactured substances typically contain compounds that are harmful to the environment. Photodegradation using photocatalysts is a common dye degradation method. Among various semiconductor materials, TiO₂ and ZnO are known to exhibit excellent photocatalytic activity. This study aims to assess the effectiveness of TiO₂ and ZnO photocatalysts in the degradation of rhodamine B dye. Several variables, including catalyst dosage (5, 15, 25, 35, 45, 55, 65, 75, and 85 mg), pH (4–8), and degradation time (60–480 min), were used to establish the photocatalytic process’s effectiveness and optimum conditions.The properties of TiO₂ and ZnO were characterized using scanning electron microscopy, X-ray diffraction, and BET analyses. Each catalyst (65 mg ZnO and 55 mg TiO₂) was added to the rhodamine B solution and exposed to a UV lamp to conduct the experiments. The results showed that TiO₂ demonstrated better photocatalytic efficiency than ZnO. The optimum degradation occurred after 6 h at pH 5. TiO₂ has a smaller crystal size and higher surface area than ZnO, contributing to its superior performance. The degradation efficiency reached 26.50% for ZnO and 48.40% for TiO₂. These data indicate that TiO₂ is more effective than ZnO for rhodamine B photodegradation under the examined conditions.

Comparative Study of Functional Monomers and Crosslinkers in the Synthesis of Molecularly Imprinted Polymers for Selective Removal of Bisphenol A

2026-03-03T06:51:32+00:00

Bisphenol A (BPA) is an endocrine-disrupting compound associated with documented environmental and health risks. This study evaluates and compares two distinct Molecularly Imprinted Polymer (MIP) architectures synthesized via bulk polymerization for selective BPA adsorption. System A utilized Methacrylic Acid (MAA) crosslinked with Ethylene Glycol Dimethacrylate (EGDMA), while System B employed Acrylamide (AM) with Trimethylolpropane Trimethacrylate (TRIM). FTIR spectroscopy confirmed template-monomer hydrogen bonding, while SEM revealed a porous morphology for System A compared to the dense surface of System B. Batch adsorption results showed that System A achieved a higher maximum capacity (Q_max = 14.74 mg/g) and imprinting factor (IF = 7.96) than System B (Q_max= 9.1 mg/g; IF = 3.33). These findings are attributed to the hydrogen-bonding affinity of MAA and enhanced site accessibility within the EGDMA matrix. Conversely, System B exhibited a higher selectivity coefficient (α = 4.1) against paracetamol than System A (α = 3.04), reflecting the influence of TRIM-induced rigidity on cavity fidelity. These findings indicate that the AM-TRIM system provides higher selectivity, while the MAA-EGDMA system demonstrates higher adsorption capacity for potential environmental applications.

Development and Validation of a Flame Atomic Absorption Spectrometry Method for Determining Cobalt in Mineral Premix for Animal Feed

2026-01-12T12:01:51+00:00

Cobalt is an essential trace element in animal feed mineral premixes, and its concentration must be precisely controlled to ensure product quality and safety. A flame atomic absorption spectrometry (FAAS) method was developed and validated for the determination of cobalt in mineral premixes, with particular focus on optimizing the sample digestion procedure. The optimized digestion protocol combined dry ashing at 600 °C for 4 hours with wet digestion using concentrated HNO₃ and H₂SO₄ in a 3:1 ratio. Validation parameters included linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, repeatability, intermediate precision, and robustness. The calibration curve demonstrated strong linearity across the tested concentration range, with a correlation coefficient of 0.9996. The limit of detection (LOD) and limit of quantification (LOQ) were 0.0817 mg/L and 0.1366 mg/L, respectively. Recovery values ranged from 84.74% to 92.86%, and repeatability yielded a relative standard deviation (RSD) of 4.69%, meeting the acceptance criterion established by the Horwitz equation. Intermediate precision and robustness assessments revealed no significant differences between analysts or between furnace temperatures of 600 °C and 650 °C. These results indicate that the optimized digestion-FAAS method is reliable and suitable for routine cobalt determination in animal feed mineral premixes.

Green Synthesis of Silver Nanoparticles Using Basilicum polystachyon Leaf Extract and Their Antibacterial Activity Against Staphylococcus aureus

2026-06-06T05:44:23+00:00

AgNPs are nanomaterials with significant potential as antibacterial agents and can be synthesized in an environmentally friendly manner using plant extracts. This study aims to synthesize AgNPs using B. polystachyon leaf extract as a bioreductant and evaluate their antibacterial activity against S. aureus. The synthesis was performed by mixing B. polystachyon leaf extract with a 0.01 M AgNO₃ at volume ratios of 1:1, 1:2, 1:3, and 1:4, followed by pH optimization in the range of pH 8–11. The synthesized AgNPs were characterized using UV–Vis spectrophotometry, FTIR spectroscopy, PSA, and XRD. Antibacterial activity was evaluated using the disk diffusion method. The results showed that optimal synthesis conditions were achieved at a volume ratio of 1:4 and a pH of 11. The UV–Vis spectrum of the synthesized AgNPs exhibited a maximum absorption peak at 412 nm. FTIR analysis revealed the presence of O–H, aromatic C=C, and C–O bonds. The average particle size was 58.79 nm (PDI = 0.29). The XRD pattern confirmed the formation of crystalline silver. The AgNPs inhibited the growth of S. aureus, with an inhibition zone diameter of 26.51 mm (very strong). Therefore, the synthesized AgNPs have the potential to be developed as antibacterial agents.