Siti Kartini Enche Ab Rahim
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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
    Integrating advanced Keggin-structure polyoxometalate into polymeric membrane to enhance photocatalytic self-cleaning and antifouling functionalities
    ( 2022-04-01)
    Koo D.C.H.
    ;
    Tan N.N.
    ;
    Ng Qi Hwa
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Low S.C.
    ;
    Yeo R.Y.Z.
    The high photocatalytic activity of environmentally benign Keggin-type polyoxometalate (POM) was introduced into polyethersulfone (PES) membrane to promote membrane anti-fouling and self-cleaning functionality. Neat PES and POM/PES hybrid membranes were synthesized via phase inversion method. X-ray diffraction (XRD) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy proved the success of synthesizing Keggin-type POM. The traits of the membranes were evaluated using scanning electron microscopy (SEM), ATR-FTIR, contact angle measurement, porosity and porometer. The hydrophilicity of all the POM/PES hybrid membranes was enhanced and resulted in the reduction of contact angle of the membrane (52.21±0.1101°, 45.11±0.6657° and 50.30±0.1054°) for 0.025, 0.05 and 0.1 wt% POM/PES hybrid membranes, respectively, compared to that of the neat PES membrane (57.30±0.0817°). Additionally, all the POM/PES hybrid membranes showed excellent anti-fouling and self-cleaning characteristics as compared to that of the neat PES membrane. 0.05 wt% POM/PES hybrid membrane outstood all the other membranes, which marks the HA rejection at 77.12% and was able to achieve flux recovery ratio (FRR) of 111.34% with temporal superhydrophilicity effect in just merely 150 seconds at 254 nm UV irradiation.
  • Publication
    Synthesis and Characterisation of Self-Cleaning TiO2/PES Mixed Matrix Membranes in the Removal of Humic Acid
    ( 2023-04-01)
    Poon Y.K.
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Ng Qi Hwa
    ;
    Hoo Peng Yong
    ;
    Abdullah N.Y.
    ;
    Amira Mohd Nasib
    ;
    Abdullah N.S.
    Membrane application is widespread in water filtration to remove natural organic matter (NOM), especially humic acid. However, there is a significant concern in membrane filtration, which is fouling, which will cause a reduction in the membrane life span, a high energy requirement, and a loss in product quality. Therefore, the effect of a TiO2/PES mixed matrix membrane on different concentrations of TiO2 photocatalyst and different durations of UV irradiation was studied in removing humic acid to determine the anti-fouling and self-cleaning effects. The TiO2 photocatalyst and TiO2/PES mixed matrix membrane synthesised were characterised using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray powder diffraction (XRD), scanning electron microscope (SEM), contact angle, and porosity. The performances of TiO2/PES membranes of 0 wt.%, 1 wt.%, 3 wt.%, and 5 wt.% were evaluated via a cross-flow filtration system regarding anti-fouling and self-cleaning effects. After that, all the membranes were irradiated under UV for either 2, 10, or 20 min. A TiO2/PES mixed matrix membrane of 3 wt.% was proved to have the best anti-fouling and self-cleaning effect with improved hydrophilicity. The optimum duration for UV irradiation of the TiO2/PES mixed matrix membrane was 20 min. Furthermore, the fouling behaviour of mixed matrix membranes was fitted to the intermediate blocking model. Adding TiO2 photocatalyst into the PES membrane enhanced the anti-fouling and self-cleaning properties.
  • Publication
    Photocatalytic Degradation of Methylene Blue Using Polyoxometalate as Photocatalyst
    ( 2023-06-09)
    Siti Kartini Enche Ab Rahim
    ;
    Azahri E.N.A.
    ;
    Hoo Peng Yong
    ;
    Ng Qi Hwa
    ;
    Abdullah N.S.
    Polyoxometalates (POM), Na2C6H4NO2. [PW12O40] have been synthesized under hydrothermal conditions and characterized. The SEM result indicates that morphology of photocatalyst was homogeneous. The performance of POM was then tested on photocatalytic degradation of methylene blue at different operating conditions. The degradation of methylene blue was dependent on several parameters, such as its initial concentration, HPOM loading and temperature. Langmuir–Hinshelwood model is usually used to describe the kinetics of this photocatalytic process. It was found that rate constant, kapp decreased with increasing initial concentrations of methylene blue. However, as increases in HPOM loading improved methylene blue degradation. The activation energy obtained was low due to this photocatalytic process being less dependent on temperature.
  • 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.
  • 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
    ;
    Pengyong Hoo
    ;
    Abdul Latif Ahmad
    ;
    Ahmad Zuhairi Abdullah
    ;
    Qihwa Ng
    ;
    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.
  • 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
    Parameters adjustments for facile synthesis of high magnetization iron oxide nanoparticles from natural sand
    ( 2024-02-01)
    Wahfiudin A.
    ;
    Pramata A.D.
    ;
    Wicaksono S.T.
    ;
    Ng Qi Hwa
    ;
    Amira Mohd Nasib
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Mohd Riduan Jamalludin
    ;
    Hoo Peng Yong
    This study explores the synthesis of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) by leveraging natural iron sand and steel wool as primary raw materials within the co-precipitation method, which reduces the cost of production compared to the commercial counterparts. The research systematically investigated the influence of the diethylamine percentage, annealing time and annealing temperature on the SPIONs’ synthesis from natural iron sand by the co-precipitation method. Fe3O4 with varying crystallite sizes, ranging from 11.5 to 14.7 nm, were confirmed. SEM highlighted the nanoparticle agglomeration, a concern addressable through surface modification techniques, as further emphasized by TEM, which confirmed the nano-scale dimensions. Magnetic saturation values were confirmed by VSM, ranging from 37 to 51 emu/g. These values established the superparamagnetic behavior, rendering the nanoparticles suitable for versatile applications. The study identifies a potential threshold effect of the diethylamine concentration on the magnetic saturation and suggests an optimum annealing temperature for energy efficiency. This research contributes valuable insights into harnessing natural iron sand for SPION synthesis, advancing cost-effective and sustainable approaches in nanomaterial development, while emphasizing the importance of parameter customization for producing high-quality SPIONs.
  • Publication
    Mathematical modelling of mass transport in linear, shunt and concentric microdialysis probes
    ( 2014)
    Siti Kartini Enche Ab Rahim
    Microdialysis is a technique for both recovering and administering substances at a target site (which may be tissues, organs, etc.), using a small equipment termed as probe. There are many types of microdialysis probes such as the linear probe, the shunt probe and the concentric probe, and the probe choices are depended on the site of implantation, whether it is for the tissue (different type of tissue for different probe design) or in the quiescent medium. Although the probe needs to be physically inserted into the site, the microdialysis probe is relatively small and is minimally-invasive (i.e., causing minimal changes or injuries to the target site). This along with many other features of microdialysis (e.g., can be performed on almost every organ and tissue, can be used on living, awake and even moving patients, etc.) make this technique very popular. Nonetheless, poor recovery, doubts related to temporal resolution, and tedious preparations plus the need of pre-runs for calibration, limits the application of this technique. These constraints are generally attributed to mass transfer limitations. In this thesis, a mathematical framework incorporating convection and diffusion equations have been proposed to represent transport phenomena in microdialysis probes. This mathematical framework is then used to analyse the possible influence of various relevant parameters on glucose (i.e., analyte) recovery. In this work, it is defined that within the probe’s membrane and probe surrounding area (PSA), the transport process is solely driven by diffusion. The model parameters and operating conditions have been obtained from literature. In the first part, a mathematical framework was constructed to represent mass transport in two primitive microdialysis probes, namely the linear and shunt probes. Using the respective mathematical frameworks, glucose recoveries under various operating conditions were compared between the two probes, which were defined to operate under similar conditions. As there is no mathematical work that has been done to evaluate these both probes, it would be interesting to see how these two microdialysis probes may perform under similar operating conditions. It is clearly seen that the frameworks were sensitive enough to show concentration changes when parameters were varied. These results were comparable to what was discussed in literature. Comparing the two probe’s performance under similar conditions, the shunt probe displayed higher glucose recoveries, which reflect better performance. The mathematical approach from the more primitive linear and shunt microdialysis probe frameworks was expanded to represent mass transport in the more complex concentric microdialysis probe. This probe is arguably the more popular and is the most commonly referred to in microdialysis literature. The framework is then used to evaluate mass transport within the probe and its surrounding area. Results on percentage recovery and overall mass transfer coefficient under various operating conditions have been discussed. Comparisons were made with the Bungay’s microdialysis framework (BMF) on mass transport performance under different design and operating parameters. The results suggested that the concentric probe framework is sensitive to parameter changes, and the concentration profiles obtained are comparable to the widely accepted BMF. This is one indication that the proposed concentric probe framework can be used to represent mass transport phenomena in such probes. The results from the numerical efforts were then compared to experimental work. It was shown that the simulated data fits well with experimental data using a 5 mm concentric probe, for membrane © This item is protected by original copyright xxvii hindrance factor, α, of 10. The comparison was done again using a similar probe, with a different length (10 mm) and fitting was also found best with α of approximately 10. It is justified that the concentric mathematical framework can be used to represent mass transport phenomena in those probes, and in one way, justifies the validity of the mathematical frameworks for the more primitive probes, beforehand.
  • Publication
    Facial synthesis of colloidal stable magnetic nanoparticles coated with high hydrophilic negative charged poly(4-styrenesulfonic acid co-maleic acid) sodium for water remediation
    ( 2023-04-01)
    Lim C.C.
    ;
    Ng Qi Hwa
    ;
    Hoo Peng Yong
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Mohd Riduan Jamalludin
    ;
    Nasib A.M.
    ;
    Wicaksono S.T.
    ;
    Pramata A.D.
    ;
    Zullaikah S.
    The enhancement of the colloidal stability of magnetite nanoparticles (MNPs) for environmental-related fields has greatly attracted researchers' attention. This study used a high hydrophilic negatively charged polyelectrolyte, poly(4-styrenesulfonic acid co-maleic acid) sodium (PSAAS), to enhance the colloidal stability of MNPs. Coating of the naked MNPs with PSAAS polyelectrolyte is a simple and rapid method to obtain colloidally stable MNPs while sustaining the chemical reactivity of MNPs in water purification. The prepared PSAAS-coated MNPs were characterized by scanning electron microscope, energy dispersive X-ray, Fourier transform infrared, zeta potential analysis, transmission electron microscope and X-ray diffraction. Moreover, the colloidal stability and adsorption performance tests of these naked MNPs and PSAAS-coated MNPs (with different concentrations of PSAAS coated) were investigated and compared. PSAAS-coated MNPs with 0.001 g/ml PSAAS coating possessed the best colloidal stability and the highest methylene blue (MB) dye removal efficiency (94.53 ± 0.69%). The adsorption isotherm and kinetic studies for the adsorption of MB onto PSAAS-coated MNPs were well-described by the Langmuir model and pseudo-second-order kinetic model. These magnetic adsorbents, with high separation efficiency, simple and low production cost and recyclable property, are promising as practicable adsorbents in water treatment.
  • Publication
    Synthesis of novel magneto-hybrid polyoxometalate composite membrane with simultaneous photocatalytic self-cleaning and antifouling functionalities
    ( 2023-10-01)
    Tan N.N.
    ;
    Ng Qi Hwa
    ;
    Siti Kartini Enche Ab Rahim
    ;
    Ahmad A.L.
    ;
    Hoo Peng Yong
    ;
    Chew T.L.
    Membrane technology is ideal for removing aqueous humic acid, but humic acid deposits cause membrane fouling, a significant challenge that limits its application. Herein, this work proposed an alternative approach to the controllably magnetically induced magneto-hybrid polyoxometalate (magneto-HPOM) nanocomposite migration toward the polyethersulfone (PES) membrane surface under a magnetic field to enhance the self-cleaning and antifouling functionalities of the membrane. Before incorporating magneto-HPOM nanocomposite into the PES casting solution, functionalized magnetite nanoparticles (F-MNP) were first coated with HPOM photocatalyst to fabricate a magneto-HPOM-PES membrane. It was shown that the apparent impacts of this novel magneto-HPOM-PES membrane on the hydrophilic behavior and photocatalytic properties of the magneto-HPOM nanocomposite improve the hydrophilicity, separation performance, antifouling and self-cleaning properties of the membrane compared with neat PES membrane. Furthermore, after exposure to ultraviolet light, the magneto-HPOM-PES membrane can be recovered after three cycles with a flux recovery ratio of 107.95%, 100.06%, and 95.56%, which is attributed to the temporal super hydrophilicity effect. Meanwhile, the magneto-HPOM-PES membrane could efficiently maintain 100% humic acid rejection for the first and second cycles and 99.81% for the third cycle. This study revealed a novel approach to fabricating membranes with high antifouling and self-cleaning properties for water treatment.[Figure not available: see fulltext.]