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Feasibility assessment of porous granules from lateritic soil and sawdust as partial cement replacement under seawater immersion
(2026-06-01)
Chaiyaput, Salisa
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Sertsoongnern, Pimchanok
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Nguyen, Trong Nghia
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Mase, Lindung Zalbuin
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Ayawanna, Jiratchaya
This study developed porous granules from lateritic soil and sawdust as an innovative approach to valorizing waste for use as a partial cement replacement. The study focused on two aspects: first, identifying suitable composition ratios and chemical agents for producing porous granules, and second, evaluating the feasibility of using granules in a cement-granule paste or as a partial cement replacement to achieve sufficient strength under seawater immersion. The findings showed that the optimal granule composition consisted of 70 wt% lateritic soil, 30 wt% sawdust, and 0.50 wt% sodium silicate, producing granules with a maximum porosity of 34% and a pore structure characterized by isolated (closed) internal pores, as indicated by qualitative observations of 3D tomographic images. When incorporated into cement paste at 20 wt% replacement with a size range of 1–2.36 mm, compressive strengths of 31–36 MPa were achieved after 7 days, meeting the standard requirements. The relationship between pore volume, granule size, and compressive strength was non-linear. Under seawater curing, samples with a 20 wt% replacement maintained strength comparable to plastic-wrapped samples, indicating stable mechanical performance during seawater immersion. These results present the feasibility of using lateritic soil-sawdust porous granules as a partial cement replacement under seawater immersion, using a simplified laboratory assessment rather than direct simulation of real marine environments. However, transport-related durability properties, such as permeability, water absorption, and ion ingress (e.g., chloride, sulfate, and magnesium ions), were not evaluated. Therefore, durability-related interpretations remain preliminary and require further validation.
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Release of microplastics from used disposable masks and wet wipes in artificial seawater under sunlight
(2026-02-01)
Sangkham, Sarawut
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Khumjan, Jiraporn
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Munkong, Narongsuk
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Sriprom, Pongsert
The global increase in plastic waste has raised significant concerns regarding microplastic pollution and its ecological and human health impacts. This study investigated the release of microplastics (MPs) from surgical masks, N95 masks, and wet wipes in artificial seawater under natural sunlight exposure and non-exposure over a 10-day period. Mass loss analysis revealed that surgical masks exhibited the greatest mass loss, followed by N95 masks and wet wipes. Fibres constituted the dominant morphology of the released particles, followed by fragments. In addition, Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy analysis confirmed that polypropylene (PP) was the primary polymer in masks, while wet wipes contained polyester-based materials. This study demonstrated that exposure to natural sunlight in artificial seawater for 10 days significantly increased microplastic release from N95 masks, wet wipes, and surgical masks compared with non-sunlight conditions (p < 0.05). Microplastic release reached 695.00 ± 100.22, 1205.33 ± 43.10, and 2619 ± 608.28 particles per item under sunlight exposure, whereas the corresponding values under non-sunlight conditions were 516.33 ± 26.73, 698 ± 99.98, and 676.00 ± 146.00 particles per item, respectively. The results indicate that disposable masks and wet wipes can release microplastic particles in artificial seawater under both sunlight and non-sunlight conditions. Furthermore, exposure to natural sunlight significantly accelerates material degradation and enhances microplastic release, suggesting that the improper disposal of these materials may contribute to microplastic pollution in marine environments.
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Modified natural seawater as growth medium for the halotolerant cyanobacterium Aphanothece halophytica to increase lipid content for biodiesel production
(2025-02-01)
Thongtha, Sitthichai
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Aryusuk, Kornkanok
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Kittiwongwattana, Chokchai
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Incharoensakdi, Aran
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Phunpruch, Saranya
Biodiesel derived from cyanobacterial oils becomes attractive as an efficient renewable energy. The present study aims to optimize growth and lipid production of the halotolerant unicellular cyanobacterium Aphanothece halophytica cultivated in natural seawater. In this study A. halophytica was able to grow in natural seawater when supplemented with low concentration of NaNO<inf>3</inf>, whereas no growth occurred without supplementation. The specific growth rate of 0.230 day-1 and cell concentration of 25.17 x 106 cells mL-1 were achieved in A. halophytica cultivated in natural seawater supplemented with 17.6 mM NaNO<inf>3</inf> and Turk Island salt solution (suitable natural seawater; SNSW) for 14 days. This growth rate was comparable to that of cells grown in normal BG11 plus Turk Island salt solution. The lipid content and fatty acid profiles of A. halophytica varied with changes in NaCl concentrations. The highest lipid content of 50.47 % and lipid productivity of 48.33 mg L-1 day-1 were obtained in cultures supplemented with 1.89 mmol C-atom L-1 glucose and 0.75 M NaCl. The optimal medium pH and cultivation temperature for lipid production was 7.5 and 25-35 °C, respectively. When cultivating A. halophytica in optimized SNSW with various NaCl concentrations, the highest contents of linoleic and linolenic acids, and the lowest contents of palmitic, stearic, and oleic acids were observed with 0.75 M NaCl. In contrast, cultures grown in optimized SNSW with 0.5 M NaCl showed fatty acid methyl ester profiles rich in monounsaturated fatty acids, which are favorable for high-quality biodiesel production.
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Self-activation of carbons derived from bio-waste cabbage for a green supercapacitor based on seawater electrolyte
(2024-12-01)
Phakkhawan, Authit
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Sakulkalavek, Aparporn
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Chanlek, Narong
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Nijpanich, Supinya
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Ngernyen, Yuvarat
Carbonized carbons (CC) derived from cabbage were self-activated via a carbonization process at 500–900 °C in Ar. CC synthesized at 800 °C (CC-800), containing KCl, CaCO<inf>3</inf>, Ca(ClO)<inf>2</inf>, K<inf>2</inf>SO<inf>4</inf>, and Ca<inf>5</inf>(PO<inf>4</inf>)<inf>3</inf>(OH), has the highest specific surface area (S<inf>BET</inf>, 130.04 m2 g−1), a high specific capacitance (64.06 F g−1), and an excellent rate capability (65.12 %). After washing the CC-800 powder in either deionized (DI) water (AC-DI) or hydrochloric acid (HCl) followed by DI water (AC-HCl-DI), S<inf>BET</inf> values increased to 919.22 and 1146.51 m2 g−1, respectively. KCl, Ca(ClO)<inf>2</inf>, and K<inf>2</inf>SO<inf>4</inf> are removed from the AC-DI, whereas all compounds are washed from the AC-HCl-DI. Removing these compounds enlarges S<inf>BET</inf> values, specific capacitance (114.47 F g−1 at 0.5 A g−1), and rate capability (68.95 %). A high capacitance retention of 97.56 % after 20,000 cycles was achieved from the AC-HCl-DI electrode with 6 M KOH. 0.6 M NaCl and seawater were applied as green electrolytes with the AC-HCl-DI electrode, resulting in the promising specific capacitance of 116.89 and 102.21 F g−1 at 0.5 A g−1, respectively. Symmetric AC-HCl-DI/seawater/AC-HCl-DI cell gives a high energy density of 2.32 Wh kg−1 at a large power density of 0.25 kW kg−1. The four serial AC-HCl-DI/seawater/AC-HCl-DI coin cells could light an LED over 60 s.
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