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Adsorptive performance of mesoporous silica-modified Bangkok clay as an alternative GCL
(2026-06-05)
Sathawong, Sidthipong
;
Asadullah
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Somsiripan, Thotsaporn
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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 m2/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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Immobilisation of soil cadmium and lead by an integrated approach of SICP and absorbent additives
(2025-09-30)
Wang, Yuchen
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Li, Mingdong
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Zhang, Shiai
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Ni, Junjun
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Kamchoom, Viroon
The combined effects of various soil additives and soybean urease-induced carbonate precipitation (SICP) on soil heavy metal immobilisation remain poorly understood. This study aims to immobilise the soil cadmium (Cd) and lead (Pb) using the SICP technique in combination with various additives, as well as to determine their optimal application dosages. Three additional additives (i.e. porous silicon, coconut shell biochar, and sorbitol) were examined. Among the three additives, coconut shell biochar combined with SICP showed the most significant improvement in the immobilisation of soil cadmium. With an optimal mixing ratio of 10% (by mass), the content of cadmium in the exchangeable state was reduced by 41% compared with the SICP-only group, and the Cd leaching concentration decreased by 45%. In the case of lead-contaminated soils, sorbitol combined with SICP yielded the most significant enhancement. An optimal dosing of 1% (by mass) reduced the lead content in the exchangeable state by 66% and the leaching concentration by 45% compared with the SICP-only group. This was attributed to the ability of sorbitol as a nucleating agent to provide additional carbonate binding sites for the formation of carbonate precipitates with lead ions. This study provides valuable experimental data and guidance for heavy metal immobilisation in contaminated sites.
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WS2Nanosheet-Based Sensors for Efficient Detection and Removal of Potentially Toxic Elements: A DFT Investigation
(2025-08-08)
Panigrahi, Puspamitra
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PS, Anuroop
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Pal, Yash
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Sharma, Munish
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Bae, Hyeonhu
This study presents a computational approach for designing nanosensors based on two-dimensional tungsten disulfide (WS<inf>2</inf>) monolayers for detecting potentially toxic elements (PTEs), including silver (Ag), arsenic (As), chromium (Cr), cadmium (Cd), mercury (Hg), and lead (Pb). Using first-principles density functional theory (DFT) calculations, the sensing performance of WS<inf>2</inf>-based materials was assessed in both atmospheric and aqueous conditions. To enhance the inherently weak adsorption and limited electronic interaction of pristine WS<inf>2</inf>with PTEs, its carrier concentration was modulated by introducing sulfur vacancies (WS<inf>2</inf>–S<inf>v</inf>) and doping with low concentrations (1.33%) of carbon (WS<inf>2</inf>–C), phosphorus (WS<inf>2</inf>–P), oxygen (WS<inf>2</inf>–O), and silicon (WS<inf>2</inf>–Si). These modifications significantly improved the material’s sensitivity and selectivity toward the targeted PTEs. Beyond atmospheric detection, the doped WS<inf>2</inf>sensor systems demonstrated strong potential for application in aqueous environments, indicating their suitability for water purification. The sensing capabilities of WS<inf>2</inf>were further substantiated by measurable alterations in electronic and charge transfer characteristics, as revealed through analyses of the density of states, work function, electrostatic potential profiles, and Bader charge analysis. To enable quantitative detection of PTEs under varying pressure, temperature, and surface coverage conditions, a statistical thermodynamics framework based on the Langmuir adsorption model was applied. Additionally, selective detection of PTEs was evaluated using nonequilibrium Green’s Functions (NEGF) formalism. Collectively, these findings highlight WS<inf>2</inf>-based nanosensors as a promising platform for the sensitive and selective adsorption and detection of toxic elements in diverse environmental settings.
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Removal of Free Fatty Acids and Impurities from Palm Oil for Use in Bio-Transformer Oils
(2024-01-01)
Phoongen, Fariz
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Thongboonchoo, Narisara
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Lertweeranontharat, Chanaphat
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Kitchaiya, Prakob
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Mantree, Nattapong
This research aims to study the removal of free fatty acids (FFA) in palm oil to make it suitable for use as transformer oil using the adsorption method. The adsorbent used in this study is hydrogels of amorphous silica. The experiments were conducted by varying the following conditions: adsorbent modification, adsorbent type, adsorbent dosage, temperature, and adsorption time. The adsorption kinetics and equilibrium were studied. The equation for estimating the required amount of adsorbent at different temperatures was developed. It was found that 3 grams of adsorbent per 100 grams of oil were required to reduce the FFA content from 691.64 to 44.53 ppm at room temperature (30°C) and an adsorption time of 1 hour and 30 minutes. This achieved the desired target of reducing the FFA content to below 50 ppm. The analysis of the chemical composition of each fatty acid before and after adsorption using the HPLC technique showed that each type of FFA, including palmitic acid, stearic acid, oleic acid, linoleic acid, and eicosanoic acid, was significantly reduced. The adsorbent was equally effective in removing each type of FFA. The electrical properties of palm oil before and after adsorption were tested. It was found that the palm oil after adsorption had a breakdown voltage of 50 kV and 61.3 kV at a test gap of 2 mm, and 32.6 kV and 37.3 kV at a test gap of 1 mm, respectively. This shows that the reduction in FFA resulted in an increase in the breakdown voltage. This increase makes the use of palm oil as a liquid insulation in transformers more efficient and safer.
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Density Functional Theory Studies of MXene-Based Nanosensors for Detecting Volatile Organic Compounds in Meat Spoilage Assessment
(2023-10-13)
Vovusha, Hakkim
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Bae, Hyeonhu
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Lee, Seunghan
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Park, Jusang
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Raza, Ali
Emission of selected volatile organic compounds (VOCs), such as methylamine (MA), dimethylamine (DMA), and trimethylamine (TMA), is associated with certain microbial reactions, causing intrinsic decomposition and spoilage of meat and fish. Efficient detection of MA, DMA, and TMA is vital for meat and fish spoilage assessment. Here, density functional theory (DFT) calculations are used to study the sensing properties of selected MXene monolayers (M<inf>2</inf>CT<inf>x</inf>; M = Ti, Nb, V; T<inf>x</inf> = O, OH, F) toward MA, DMA, and TMA. We found that the binding energies of MA (−0.29 to −1.08 eV), DMA (−0.39 to −1.15 eV), and TMA (−0.28 to −1.19 eV) on M<inf>2</inf>CT<inf>x</inf> are ideal for reversible sensing. Appropriate binding of these VOCs is associated with measurable changes in the electronic properties of M<inf>2</inf>CT<inf>x</inf>, which is essential for a highly efficient sensing mechanism. Further, we used the Langmuir adsorption model to explore the sensing characteristics of M<inf>2</inf>CT<inf>x</inf> monolayers in varied temperature and pressure environments. Among the studied systems, Nb<inf>2</inf>C(OH)<inf>2</inf> exhibits excellent sensing capabilities toward DMA and TMA at concentrations below parts per million (ppm), whereas Nb<inf>2</inf>CF<inf>2</inf> exhibits selective adsorption of MA at concentrations below ppm. We strongly believe that our findings will pave the way for the development of highly sensitive nanosensors for monitoring the spoilage of meat and fish products.
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EFFECTS OF ACID AND ALKALINE TREATMENTS ON EFFICIENCY OF DIATOMACEOUS EARTH IN REMOVAL OF TETRACYCLINE IN AQUEOUS SOLUTION
(2023-09-01)
Sinpichai, Sarawut
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Yuangsawad, Ratanaporn
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Na-Ranong, Duangkamol
Contamination of tetracycline (TC) in environment may cause serious problems relating to increase of antibiotic resistance and development of new deceases. This paper focuses on TC removal by simple adsorption treatment and utilization of natural diatomaceous earth (NDE) as a cheap adsorbent. To improve efficiency of NDE, an impregnation method using acid (H2SO4) or base (KOH) was applied to modify NDE and influences of important activation parameters, concentration of reagent (Creagent), ratio of NDE weight and activating solution volume (NDE-to-Sol), temperature (Tact) and time (tact), on the efficiencies of the obtained acid and base activated diatomaceous earths (ADE and BDE) were investigated. Batch adsorption experiment was performed at the same condition to evaluate TC adsorption capacities at equilibrium (qe, TC) of NDE, ADE and BDE. It was found that acid activation negatively affected qe, TC and increases of CH2SO4, Tact and tact resulted in poorer ADE. In contrast, qe, TC was successfully enhanced through activation by KOH; Tact and tact played more significant roles on the enhancement, comparing with CKOH and NDE-to-Sol; impregnation at higher Tact and longer tact could improve efficiency of BDE and the best BDE (BDE-B) with the highest qe, TC (86.31 mg/g) was obtained at 3 M, 0.1 g/ml, 80 °C and 9 h.
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Nanoporous Carbon from Oil Palm Leaves via Hydrothermal Carbonization-Combined KOH Activation for Paraquat Removal
(2022-08-01)
Chanpee, Sirayu
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Kaewtrakulchai, Napat
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Khemasiri, Narathon
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Eiad-ua, Apiluck
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Assawasaengrat, Pornsawan
In this study, nano-porous carbon was completely obtained from oil palm leaves (OPL) by hydrothermal pretreatment with chemical activation, using potassium hydroxide (KOH) as an activating agent. Potassium hydroxide was varied, with different ratios of 1:0.25, 1:1, and 1:4 (C: KOH; w/w) during activation. The physical morphology of nano-porous carbon has a spongy, sponge-like structure indicating an increase in specific surface area and porosity with the increasing amount of KOH activating agent. The highest specific surface area of OPL nano-porous carbon is approximately 1685 m2·g−1, with a total pore volume of 0.907 cm3·g−1. Moreover, the OPL nano-porous carbon significantly showed a mesoporous structure designed specifically to remove water pollutants. The adsorptive behavior of OPL nano-porous carbon was quantified by using paraquat as the target pollutant. The equilibrium analyzes were explained by the Langmuir model isotherm and pseudo-second-order kinetics. The maximum efficiency of paraquat removal in wastewater was 79%, at a paraquat concentration of 400 mg·L−1, for 10 min in the adsorption experiment. The results of this work demonstrated the practical application of nano-porous carbon derived from oil palm leaves as an alternative adsorbent for removing paraquat and other organic matter in wastewater.
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As(III) removal under the presence of competitive anions using the calcined ground oyster shell as the adsorbent
(2020-02-11)
Khownpurk, P.
;
Chandra-Ambhorn, W.
The calcined ground oyster shell was used as the adsorbent to remove As(III) from contaminated water under the presence of anions. The solubility and precipitation tests indicated that As(III), NO<inf>3</inf> −, and SO<inf>4</inf> 2- were removed by adsorption process whereas HPO<inf>4</inf> 2- was removed by precipitation and adsorption processes. The adsorption results showed that, in bi-solutes, HPO<inf>4</inf> 2- strongly interfered with As(III) removal. In the case of tri- and tetra-solutes, the adsorption performances of As(III) and anions depended on (1) the binding affinity between the sorption sites and adsorbates, (2) observed adsorption rate constant of adsorbates, (3) electrostatic interaction, and (4) adsorbates interaction.
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Facile preparation of copper impregnated aluminum pillared montmorillonite: nanoclays for wastewater treatment
(2016-01-01)
Tepmatee, P.
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Siriphannon, P.
Copper impregnated aluminum pillared montmorillonites (Cu-iAlpill-MMTs) were prepared by adding Cu2+ solution into dried aluminum polyohydroxy cation intercalated montmorillonite using various Cu2+ concentrations, i.e. 4, 7, 10 and 13 wt% and then calcining at 500oC. The Cu-iAlpill-MMTs possessed slit-liked mesopores with pore diameters of 3.3-3.8 nm and ~6-35 nm as observed from the nitrogen adsorption isotherms. The mesopore quantities of Cu-iAlpill-MMTs gradually decreased with the increase of impregnated Cu2+ concentrations. The impregnated CuO occupied not only the interior interlayers, but also the exterior surfaces of Cu-iAlpill-MMTs. The Cu-iAlpill-MMTs with 10 and 13 wt% of impregnated Cu2+ could inhibit the growth of Escherichia coli. The Cu-iAlpill-MMTs effectively acted as the heterogeneous catalyst for removal reactive orange 16 (RO16) in Fenton or photo-Fenton oxidation treatments. The higher impregnated Cu2+ and/or the longer treatment time brought about the higher percentage of RO16 removal.
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Water-soluble chitosan intercalated montmorillonite nanocomposites for removal of basic blue 66 and basic yellow 1 from aqueous solution
(2013-04-05)
Kaemkit, Chutima
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Monvisade, Pathavuth
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Siriphannon, Punnama
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Nukeaw, Jiti
Water-soluble chitosan intercalated montmorillonite (wCTS/MMT) nanocomposites were modified and characterized by using Fourier transform infrared, thermogravimetric analysis, and X-ray diffractometer techniques. Two types of wCTS, namely, low molecular-weight chitosan (L-wCTS) and hydroxyethylacryl chitosan (H-wCTS) were synthesized and applied. The batch adsorption experiments on these nanocomposites were conducted by using basic dyes, that is, Basic Blue 66 and Basic Yellow 1 (BY1). The adsorption capacities of sodium montmorillonite (Na-MMT), chitosan, L-wCTS/MMT, and H-wCTS/MMT were measured and compared. The results showed that the adsorption capacities of wCTS/MMT nanocomposites were higher than those values of Na-MMT and chitosan. The adsorption kinetics of wCTS/MMT nanocomposites for BY1 were studied. It was described that the adsorption processes were better fitted by pseudo-second-order equation. The Langmuir and the Freundlich models were used to fit the adsorption isotherm. It was indicated that the adsorption isotherms followed the Langmuir model. The values of the maximum adsorption capacity of L-wCTS/MMT and H-wCTS/MMT adsorbents were at 188.7 and 294.1 mg/g, respectively. © 2012 Wiley Periodicals, Inc.

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