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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A Novel Tri-Functionality pH-Magnetic-Photocatalytic Hybrid Organic-Inorganic Polyoxometalates Augmented Microspheres for Polluted Water Treatment

2023-02-01 , Yee L.Y. , Ng Qi Hwa , Siti Kartini Enche Ab Rahim , Hoo Peng Yong , Chang P.T. , Ahmad A.L. , Low S.C. , Shuit S.H.

The severe water pollution from effluent dyes threatens human health. This study created pH-magnetic-photocatalytic polymer microspheres to conveniently separate the photocatalyst nanoparticles from the treated water by applying an external magnetic field. While fabricating magnetic nanoparticles’ (MNPs) microspheres, incorporating 0.5 wt.% iron oxide (Fe3O4) showed the best magnetophoretic separation ability, as all the MNPs microspheres were attracted toward the external magnet. Subsequently, hybrid organic–inorganic polyoxometalates (HPOM), a self-synthesized photocatalyst, were linked with the functionalized magnetic nanoparticles (f-MNPs) to prepare augmented magnetic-photocatalytic microspheres. The photodegradation dye removal efficiency of the augmented magnetic-photocatalytic microspheres (f-MNPs-HPOM) was then compared with that of the commercial titanium dioxide (TiO2) photocatalyst (f-MNPs-TiO2). Results showed that f-MNPs-HPOM microspheres with 74 ± 0.7% photocatalytic removal efficiency better degraded methylene orange (MO) than f-MNPs-TiO2 (70 ± 0.8%) at an unadjusted pH under UV-light irradiation for 90 min. The excellent performance was mainly attributed to the lower band-gap energy of HPOM (2.65 eV), which required lower energy to be photoactivated under UV light. The f-MNPs-HPOM microspheres demonstrated excellent reusability and stability in the photo-decolorization of MO, as the microspheres retained nearly the same removal percentage throughout the three continuous cycles. The degradation rate was also found to follow the pseudo-first-order kinetics. Furthermore, f-MNPs-HPOM microspheres were pH-responsive in the photodegradation of MO and methylene blue (MB) at pH 3 (acidic) and pH 9 (alkaline). Overall, it was demonstrated that using HPOM photocatalysts in the preparation of magnetic-photocatalytic microspheres resulted in better dye degradation than TiO2 photocatalysts.

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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.

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Application of the novel pH-catalytic-magnetic tri-functionalities augmented bead for removal of organic dye pollutants

2021-11-01 , Yee L.Y. , Ng Q.H. , Shuit S.H. , Siti Kartini Enche Ab Rahim , Mohammad Nawi D. , Low S.C.

A tri-functionality magnetic nanoparticles (MNPs) are crucial for environmental remediation. This research focused on the synthesis of pH-catalytic-magnetic polymer beads for dye removal by using phase inversion technique. In 15 wt% of polyethersulfone (PES) polymer possessed the highest porosity (80%) was used in the synthesis of MNPs-PES beads. The methylene blue (MB) removal efficiency of MNPs-PES beads and PES beads was 72.94% and 62.67%, respectively. Similarly, the removal efficiency of methyl orange (MO) dye is higher for MNPs-PES beads (38.56%) compared to PES beads (34.16%). Besides, the removal efficiency for MB dye by MNPs-PES beads increased from 77.59% to 96.90% when solution pH increased from 3 to 9 while removal of MO dye increased from 61.14% to 74.35% when solution pH decreased from 9 to 3. Moreover, the removal efficiency for MB dye increased from 72.94% to 93.43% when H2O2 is added. Additionally, MNPs-PES beads were recollected successfully using external magnet. These indirectly proved that the MNPs-PES beads were responsive towards the tri-functionalities of pH-catalytic-magnetic. Lastly, the adsorption of MB dye onto MNPs-PES beads were fitted well to Langmuir isotherm model and pseudo-second-order model with both correlations R2 of more than 0.98.

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