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Author: search.filters.author.Imsuwan, PattareewanStart date: 2020

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    Fungal Transformation and Oxalate-Mediated Mineralization of Heavy Metal Oxides by Aspergillus aculeatus
    (2026-04-01)
    Sawangchart, Thanakorn
    ;
    Chutipaijit, Sutee
    ;
    Meksiriporn, Bunyarit
    ;
    Narueban, Worapat
    ;
    Tilokkarn, Worrathon
    Fungal transformation is increasingly recognized as an important process influencing metal solubilization and immobilization in soil environments. In this study, a fungal strain (PTW4) isolated from mining-contaminated soil was molecularly identified as Aspergillus aculeatus. The strain was evaluated for its ability to solubilize and transform several heavy metal oxides, including ZnO, Pb<inf>3</inf>O<inf>4</inf>, Cu<inf>2</inf>O, and MoO<inf>3</inf>. PTW4 produced consistent halo formation across all tested oxides, accompanied by progressive acidification of the culture medium, suggesting organic acid-mediated solubilization. Characterization of extracellular precipitates by SEM-EDS and XRD indicated mineral phases consistent with oxalate-associated biominerals, including zinc oxalate dihydrate (ZnC<inf>2</inf>O<inf>4</inf>·2H<inf>2</inf>O), lead oxalate (PbC<inf>2</inf>O<inf>4</inf>), and copper oxalate hydrate (CuC<inf>2</inf>O<inf>4</inf>·xH<inf>2</inf>O). These minerals represent low-solubility phases that may reduce metal mobility in the surrounding environment. In contrast, molybdenum did not precipitate under the experimental conditions, suggesting metal-specific constraints in fungal biomineralization processes. Although organic acid production was not directly quantified, identification of oxalate mineral phases supports an oxalate-associated mineralization mechanism. Overall, the results provide evidence for heavy metal solubilization and selective extracellular precipitation consistent with oxalate biomineral formation by A. aculeatus PTW4, highlighting its potential relevance to fungal-mediated bioremediation and selective bioleaching processes.
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    Characterization and proximate analysis of composite biochar briquette from oil palm frond and red clay
    (2025-01-01)
    Suwankamnoed, Saipin
    ;
    Imsuwan, Pattareewan
    ;
    Tilokkarn, Worrathon
    ;
    Meksiriporn, Bunyarit
    ;
    Sutjaritvorakul, Thanawat
    The ultimate goal of this research is to create effective and environmentally friendly biochar briquettes from oil palm frond (OPF) waste. Red clay, a plentiful local resource, has been demonstrated to improve the properties of fuel briquettes. In this study, the tested composite briquettes (biochar:red clay:starch by weight) were prepared in the following ratios: 40:55:5 (T2), 50:45:5 (T3), 60:35:5 (T4), and 70:25:5 (T5), while the control sample (T1) consisted of 95:5 (biochar:starch). All of the different ratios were analyzed using proximate analysis. The results showed moisture content ranging from 7.35% to 8.47%, ash content from 29.75% to 49.82%, volatile matter from 15.63% to 17.47%, and fixed carbon from 25.31% to 46.48%. Among them, T4 exhibited the lowest moisture and ash content and the highest calorific value at 5,650 cal/g, making it the optimal candidate for further investigation. A comprehensive analysis of T4 was conducted using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The techniques revealed the morphological structure and inorganic components that contribute to the energy efficiency of T4. The study also examined air pollutant emissions. T4 produced lower emissions of pollutants such as carbon monoxide (CO), carbon dioxide (CO<inf>2),</inf> total volatile organic compounds (TVOCs), formaldehyde (HCHO), and particulate matter (PM<inf>1.0</inf> and PM<inf>2.5</inf>) compared to the OPF biochar briquette without red clay (T1). Composite biochar briquettes made from OPF and red clay (T4) are safe and suitable for use as a fuel source for household applications like cooking and heating. This research contributes to the development of the green bioeconomy and supports sustainable energy initiatives.