Siti Kartini Enche Ab Rahim
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Preferred name
Siti Kartini Enche Ab Rahim
Official Name
Siti Kartini, Enche Ab Rahim
Alternative Name
Rahim, S. K.Enche Ab
Enche Ab Rahim, S. K.
Rahim, Siti Kartini Enche Ab
Main Affiliation
Scopus Author ID
57115278300
Researcher ID
EJE-7983-2022

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  • Publication
    Facile synthesis of magnetophoretic augmented adsorbent for water remediation
    ( 2024-03)
    Chuan Chuan Lim
    ;
    Ng Qi Hwa
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Hoo Peng Yong
    ;
    Siew Hoong Shuit
    ;
    Sigit Tri Wicaksono
    In this new era of globalization, magnetic adsorbents have gained vast attention from researchers in wastewater treatment applications. In this study, sulphonated magnetic multi-walled carbon nanotubes (S-MMWCNTs) were used to remove methylene blue (MB) from an aqueous solution. The S-MMWCNTs are characterized by various analytical methods to investigate their adsorbent features. Adsorption behaviours of the as-prepared composites affected by solution pH and contact time were systematically studied and discussed. The adsorption kinetic data fit the pseudo-second-order kinetic model well. Moreover, the MB removal efficiency of S-MMWCNTs only drops slightly (~6.5%) after five consecutive adsorption cycles, showing their good stability and recyclability.
  • Publication
    Sulfonated magnetic multi-walled carbon nanotubes with enhanced bonding stability, high adsorption performance, and reusability for water remediation
    (Springer, 2023)
    Lim Chuan Chuan
    ;
    Siew Hoong Shuit
    ;
    Ng Qi Hwa
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Wei Ming Yeoh
    ;
    Hoo Peng Yong
    ;
    Soon Wah Goh
    In view of the simple and rapid conveniency of magnetic separation, magnetic nanocomposites had notably gained attention from researchers for environmental field applications. In this work, carboxylated magnetic multi-walled carbon nanotubes (c-MMWCNTs) and novel sulfonated MMWCNTs (s-MMWCNTs) were synthesized by a facile solvent-free direct doping method. Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, energy dispersive X-ray, vibrating sample magnetometer, and point of zero charge analyses confirmed the successful doping of the Fe3O4 nanoparticles into the functionalized MWCNTs to form MMWCNTs. Besides, the bonding stabilities of both c-MMWCNTs and s-MMWCNTs were compared, and results showed that s-MMWCNTs possessed more substantial bonding stability than that of c-MMWCNTs with significantly less leaching amount of Fe3O4. The adsorption capacity of s-MMWCNTs was higher than that of c-MMWCNTs owing to the stronger electronegativity sulfonic group in s-MMWCNTs. Moreover, the reusability experiments proved that the adsorbent remained consistently excellent MB removal efficiency (R > 94%) even reused for twelve cycles of batch adsorption. The finding of the present work highlights the simple fabrication of novel s-MMWCNTs and its potential to be served as a promising and sustainable adsorbent for water remediation owing to its enhanced bonding stability, high adsorption performance, magnetic separability, and supreme recyclability.
  • Publication
    An insight into the adsorptive, kinetic, and mechanistic behavior of the sulfonated magnetic multi-walled carbon nanotubes adsorbent in the removal of Methylene blue
    (Springer, 2025)
    Chuan Chuan Lim
    ;
    Ng Qi Hwa
    ;
    Siew Hoong Shuit
    ;
    Soon Wah Goh
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Hoo Peng Yong
    A simple and environmentally friendly, facile solvent-free direct doping (FSFDD) approach was employed to synthesize sulfonated magnetic multi-walled carbon nanotubes (s-MMWCNTs) which in turn employed for the eliminating of methylene blue (MB) dye from aqueous solution. While prior studies have emphasized the synthesis and innovation points of s-MMWCNTs, this work delves into the fundamental adsorption behaviors (adsorption isotherm, kinetic, thermodynamic and mechanism analysis) to provide a deeper understanding of the interactions between the adsorbent and methylene blue (MB). The developed s-MMWCNTs were characterized by zeta potential analysis, transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET). Moreover, the characterization of spent s-MMWCNTs by X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray (SEM-EDX) and Fourier transform infrared (FT-IR) were carried out to compare their characteristics to the freshly synthesized s-MMWCNTs. Results indicated that the Freundlich isotherm model was the best-fitted model, providing a maximum adsorption capacity of 44.64 mg g− 1. As for the adsorption kinetic studies, the MB adsorption onto s-MMWCNTs was discovered to comply with the pseudo-second-order model. Besides, the thermodynamic results suggested that the adsorption process of MB onto s-MMWCNTs occurred endothermically with spontaneity. Furthermore, the adsorption mechanisms encompassed electrostatic interaction, hydrogen bonding and π–π stacking interaction with the electrostatic interaction as the most salient attractive force in the MB adsorption onto s-MMWCNTs.
  • Publication
    Removal of methylene blue using magnetic multi-walled carbon nanotubes: process optimization study
    ( 2020-12-18)
    Lim C.C.
    ;
    Shuit S.H.
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Hoo Peng Yong
    ;
    Ng Qi Hwa
    Adsorption is the most common methods used in industry for the removal of dye. In this study, magnetic multi-walled carbon nanotubes (MMWCNTs) was served as adsorbent for the removal of methylene blue (MB). Statistical optimization of the MB removal efficiency via response surface methodology coupled with central composite design was performed and reported. It was observed that all three experimental parameters: adsorption temperature (25-50 C), MB concentration (10-50 ppm) and MMWCNTs dosage (0.01-0.05 g/20mL) were significant in the removal of MB. The optimized conditions of 99.21 % MB removal efficiency can be achieved at adsorption temperature of 38 C, MB concentration of 23 ppm and MMWCNTs dosage of 0.033 g/20mL. The verification of the prediction was performed with 3 repeated experiments and the results were found to be in good agreement with the experimental data with only 0.21 % error.
      22  3
  • 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
    ;
    Hoo Peng Yong
    ;
    Abdul Latif Ahmad
    ;
    Ahmad Zuhairi Abdullah
    ;
    Ng Qi Hwa
    ;
    Siewhoong Shuit
    ;
    Siti Kartini Enche Ab Rahim
    ;
    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.