Now showing 1 - 4 of 4
  • Publication
    Recent advancements in smart materials for the removal of organic, inorganic and microbial pollutants in water treatment: a review
    (Elsevier, 2025-02)
    Soon Wah Goh
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    ; ;
    Siew Chun Low
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    ;
    Ryan Yow Zhong Yeo
    ;
    Thiam Leng Chew
    ;
    Zeinab Abbas Jawad
    As the expeditious urban and industrial expansion, a substantial portion of wastewater is produced annually, posing a significant threat to environmental contamination and dwindling the availability of clean water resources. Water contaminants are generally categorized into organic, inorganic, and microbial pollutants. This escalating water pollution crisis has initiated the research community to innovate novel, effective and economical cost methods for water treatment applications. Among the approaches, adsorption has been marked by its importance in water treatment. Recent advancements in the field have focused on developing smart adsorbent materials capable of modifying their physicochemical properties in response to various external stimuli (light and magnetic field) and internal stimuli (thermal and pH fluctuation). The exploration of smart materials has captivated the interest of researchers worldwide and opened up exciting avenue for more efficient water treatment outcomes towards removing different types of pollutants. Notably, these smart materials demonstrate high pollutant uptake and release efficacy when responding to specific stimuli changes, ensuring efficient removal of contaminants and exerting self-cleaning properties. Such materials offer an environmentally benign advantage by eliminating the need for toxic organic solvents during regeneration. The review compiles and highlights the characteristics and performance of several stimuli-responsive smart materials, including thermal, light, magnetic and pH regarding organic, inorganic and microbial pollutants removal efficiencies. A particular focus is given to multi-stimuli responsive materials in environmental applications that represent the modern era and transformation of water treatment methodologies, followed by a discussion on the challenges and prospects of this particular research area.
  • Publication
    A Review on Microdialysis Calibration Methods: the Theory and Current Related Efforts
    ( 2017-07-01)
    Kho C.M.
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    ;
    Zainal Arifin Ahmad
    ;
    Norazharuddin Shah Abdullah
    Microdialysis is a sampling technique first introduced in the late 1950s. Although this technique was originally designed to study endogenous compounds in animal brain, it is later modified to be used in other organs. Additionally, microdialysis is not only able to collect unbound concentration of compounds from tissue sites; this technique can also be used to deliver exogenous compounds to a designated area. Due to its versatility, microdialysis technique is widely employed in a number of areas, including biomedical research. However, for most in vivo studies, the concentration of substance obtained directly from the microdialysis technique does not accurately describe the concentration of the substance on-site. In order to relate the results collected from microdialysis to the actual in vivo condition, a calibration method is required. To date, various microdialysis calibration methods have been reported, with each method being capable to provide valuable insights of the technique itself and its applications. This paper aims to provide a critical review on various calibration methods used in microdialysis applications, inclusive of a detailed description of the microdialysis technique itself to start with. It is expected that this article shall review in detail, the various calibration methods employed, present examples of work related to each calibration method including clinical efforts, plus the advantages and disadvantages of each of the methods.
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  • Publication
    Facile synthesis of hybrid-polyoxometalates nanocomposite for degradation of cationic and anionic dyes in water treatment
    (Academic Enhancement Department, King Mongkut's University of Technology North Bangkok, 2025-03)
    Wei Wei Leow
    ;
    Alvin Duke
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    ; ;
    Norazharuddin Shah Abdullah
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    ; ;
    Photocatalysis emerges as a promising method for treating organic dye contaminated wastewater. This process involves the use of photocatalysts through light activation, typically semiconductors such as titanium dioxide (TiO2) or polyoxometalates (POM) to generate reactive species capable of degrading organic pollutants. Several factors influence the photodegradation of ionic and cationic dyes including chemical properties, reaction mechanism and degradation efficiency. This work evaluated photodegradation performance of methyl orange (MO) and malachite green (MG) dyes using hybrid-polyoxometalate (HPOM) photocatalyst. Fourier Transform Infrared Spectroscopy (FTIR) identified the characteristic band at 3463.66 cm–1 (O-H) and 997.74 cm–1 (W-O). Scanning Electron Microscopy (SEM) revealed the presence of rod-like and granular structures in HPOM, representing silver acetate and sodium tungstate. X-ray diffraction (XRD) confirmed characteristic peak of Keggin structure, revealing high crystallinity of HPOM. UV-assisted photodegradation was evaluated on different parameters (initial dye concentration, photocatalyst dosage and pH), highlighting HPOM’s better affinity for degrading cationic dye. The optimum photodegradation conditions for MG and MO dyes were 20 ppm dye concentration, 100 mg photocatalyst dosage, and pH 7 and 8, respectively. The kinetic data was fitted with the Langmuir Hinshelwood kinetic model, indicating pseudo-first-order kinetics. HPOM exhibited a higher rate constant, k for MG (k = 0.0068 min–1) than MO (k = 0.0029 min–1).
      1  1
  • Publication
    Plant-based calcium silicate from rice husk ash: A green adsorbent for free fatty acid recovery from waste frying oil
    ( 2024-02-29)
    Zainor Syahira Zainal
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    ;
    Abdul Latif Ahmad
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    Ahmad Zuhairi Abdullah
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    ;
    Siewhoong Shuit
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    ;
    Andas J.
    Driven by the urgent need for a solution to tackle the surge of rice husk (RH) and waste frying oil (WFO) waste accumulation at a global scale, this report highlights the use of calcium silicates (CS) extracted from acid-pre-treated rice husk ash (RHA) for free fatty acid (FFA) removal from WFO as conventional RHA shows limited FFA adsorption performance. A novel alkaline earth silicate extraction method from acid-pre-treated RHA was outlined. The structural and behavioural attributes of the synthesised CS were identified through BET, SEM-EDS, and XRD analyses and compared to those of RHA. Notable morphology and structural modification were determined, including reducing specific surface areas, mitigating from amorphous to crystalline structure with regular geometric forms, and detecting Si–O–Ca functional groups exclusive to CS adsorbents. A comparison study showed superior lauric acid (LA) adsorption performance by CS absorbents over acid-pre-treated RHA, with a significant increase from 0.0831 ± 0.0004 mmol LA/g to 2.5808 ± 0.0011 mmol LA/g after 60 min. Recognised as the best-performing CS adsorbent, CS-1.0 was used for further investigations on the effect of dosage, LA concentration, and temperature for efficient LA adsorption, with up to 100% LA removal and 5.6712 ± 0.0016 mmol LA/g adsorption capacity. The adsorption isotherm and kinetic studies showed LA adsorption onto CS-1.0 followed Freundlich isotherm with KF = 0.0598 mmol(1-1/n) L(1/n) g−1 & Qe,cal = 3.1696 mmol g−1 and intraparticle diffusion model with kid = 0.1250 mmol g−1 min0.5 & Ci = 0.9625 mmol g−1, indicating rapid initial adsorption and involvement of carboxylate end of LA and the calcium ions on the CS-1.0 in the rate-limiting step. The high equilibrium adsorption capacity and LA adsorption rate indicated that the proposed CS-1.0 adsorbent has excellent potential to recover FFA from WFO effectively.