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    Item type:Publication,
    Adsorptive performance of mesoporous silica-modified Bangkok clay as an alternative GCL
    (2026-06-05)
    Sathawong, Sidthipong
    ;
    Asadullah
    ;
    Somsiripan, Thotsaporn
    ;
    Tohdee, Kanogwan
    ;
    Jongsomjit, Bunjerd
    This study investigates the adsorption performance and characterisation of mesoporous silica-modified Bangkok clay (BKC) as a geosynthetic clay liner (GCL) for removal of heavy metal in aqueous solution. BKC was modified with mesoporous SBA-15 to create a mesoporous silica-coated clay (5SBS), enhancing its surface area, porosity, and adsorption efficiency. The materials were characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy techniques while adsorption experiments of Cu(II), Zn(II), and Cd(II) ions under controlled conditions in ternary systems. The 5SBS composite exhibited superior physicochemical characteristics, including a BET surface area of 67.45 m<sup>2</sup>/g and well-distributed mesopores. Adsorption kinetics followed a pseudo-second-order model, indicating chemisorption as the dominant mechanism. Equilibrium isotherm data fit best with the Langmuir and Sips models, suggesting monolayer adsorption on homogenous surfaces. The maximum uptake capacities for 5SBS were 31.74, 17.96, and 14.26 mg/g for Cu(II), Zn(II), and Cd(II), respectively, outperforming unmodified BKC and closely matching bentonite. Enhanced thermal stability and minimal pore structure degradation post-adsorption confirmed its suitability for harsh environmental conditions. Metal adsorption has mainly occurred at the surface of the mesoporous silica-modified clay by bonding with surface functional groups. Hydraulic conductivity results further indicate that SBA-15 modification effectively reduces permeability and chemical sensitivity of BKC, maintaining performance comparable to bentonite through stable pore-blocking mechanisms. These findings highlight 5SBS as sustainable alternative to bentonite in GCL, with potential implications for contaminant protection.
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    Item type:Publication,
    The effect of desiccation cracks on water infiltration in landfill cover under extreme climate scenarios
    (2025-04-01)
    Apriyono, Arwan
    ;
    Yuliana, Yuliana
    ;
    Kamchoom, Viroon
    ;
    Leung, Anthony Kwan
    ;
    Jotisankasa, Apiniti
    Predicting water infiltration in clay poses a significant challenge, primarily due to the presence of desiccation cracks, which are amplified by extreme climate. Accurate methods for calculating water infiltration, considering crack variations under extreme climates are essential especially for landfill covers. The objective of this study is to explore the relationship between crack intensity factor (CIF) and water infiltration in high-plasticity clay, focusing on seasonal changes and extreme climate conditions. A series of double-ring infiltration tests was conducted in the field to observe the impact of desiccation cracks on water infiltration. Subsequently, a modified Green–Ampt method incorporating CIF was developed and validated against these field test results to improve water infiltration predictions. This study revealed that the maximum CIF was notably higher in the second dry season (11.4 %) than that in the first one (8.1 %), indicating soil structural degradation. An exponential correlation was observed between increased CIF and infiltration rates, attributed to cracks creating preferential pathways. In extreme climate scenarios, CIF increases could surpass 15 %, potentially elevating soil's saturated hydraulic conductivity (K<inf>s</inf>) by over 85 % relative to current climate conditions.