Wan Khairunnisa Wan Ramli
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Preferred name
Wan Khairunnisa Wan Ramli
Official Name
Wan Khairunnisa, Wan Ramli
Alternative Name
Ramli, W. K. W.
Ramli, Wan K. W.
Ramli, Wan Khairuzzaman Wan
Ramli, W. K. Wan
Main Affiliation
Scopus Author ID
18435070700
Researcher ID
DNN-0208-2022

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Publication

Exsolution enhancement of metal-support CO oxidation perovskite catalyst with parameter modification

2021-05-24 , Lew G.L. , Naimah Ibrahim , Abdullah S. , Wan Daud W.R. , Wan Khairunnisa Wan Ramli

This study aimed to further tune the capability of active metal exsolution onto the surface of the CO oxidative perovskite catalyst La0.7Ce0.1Co0.3Ni0.1Ti0.6O3 by tuning the reducing parameter. Under same calcination temperature of 800℃, XRD analysis shown that the precursors with calcination duration of 6 hours (S2T8H6) was able to achieve similar crystalline structure to those with calcination duration of 12 hours (S2T8H12). In order for the active metal (CoNi) to be exsolved onto the perovskite surface, reducing parameter such as temperature and duration are deemed crucial to the reduction process. The exsolution of the active metals was observed when the samples were treated under reducing condition with varying temperatures of 550℃ and 700℃ and duration from 200 to 300 minutes. Through comparison with their EDX readings, S2T8H6 treated under 700℃ and 300 minutes (S2T8H6-R7H5) achieved the highest weight percentage of surface Cobalt and Nickel of 3.83 and 2.81. It was clear that by tuning the temperature and duration of reduction, the exsolution of the active metals onto the surface of the perovskite could be improved resulting in better exposure and dispersion of active metals onto the surface of catalyst.

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Fe₃O₄-Doped polysulfane membrane for enhanced adsorption of copper from aqueos solution

2024-01-01 , Wan Khairunnisa Wan Ramli , Nur Maisyatul Syalina Abdul Wahab , Siti Khalijah Mahmad Rozi , Syumayyah Rasis , Gavin Chew Tiong Chuen , Lew Guo Liang

Water pollution, especially from industrial wastewater has become one of the major global environmental problems. As the result of rapid industrialization, the expansion of industries such as the electroplating industry has resulted in an increase in heavy metals effluent, especially copper, in the wastewater, and this poses detrimental effects on the biodiversity and environment. The abatement of copper pollution has received widespread attention, and continuous research advancement has been observed in adsorption and membrane technology. Nanofiltration membranes with nanopores recorded higher suitability to remove ions but at the expense of membrane fouling as a result of the formation of contaminants on the surface layer that blocks the diffusion of contaminants into the membrane substructure. This research highlights the incorporation of Fe3O4 nanoparticles into the polysulfone (PSf) membrane matrix as an adsorptive membrane and their possible adsorption mechanism towards Cu, which can manifest the combined characteristics of both removal techniques. Fe3O4 nanoparticles were synthesized using the co-precipitation method. Fe3O4-doped PSf membranes were then synthesized with various concentrations of Fe via the Non-solvent Induced Phase Separation (NIPS) technique. The physicochemical properties of the Fe nanoparticles and the membranes were evaluated using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), water contact angle and porosity testing. Crystal phase analysis confirmed the formation of magnetite Fe3O4 in a cubic structure. Agglomerations of Fe NPs on the membrane surface were observed for membranes with lower Fe concentrations, suggesting the possibility of poor blending and this contributed to the lower adsorption capability of these membranes. Membranes with 2 wt.% Fe concentration (Fe-2.0) exhibited the highest Cu(II) ions adsorption capacity of 637 mg/g, which is trifold of those recorded for pristine PSF membrane (Fe-0.0). The adsorption data of Cu adsorption were best fitted into the Temkin isotherm and pseudo-second-order models, suggesting an adsorption mechanism involving an exothermic chemical interaction between Cu ions and the Fe3O4 NPs within the membrane. This research confirms the potential of incorporating Fe3O4 in the PSf membrane backbone to enhance Cu removal as an adsorptive membrane, even at lower NP concentrations.

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Demonstration of chemistry at a point through restructuring and catalytic activation at anchored nanoparticles

2017 , Dragos Neagu , Evangelos I. Papaioannou , Wan Khairunnisa Wan Ramli , David N. Miller , Billy J. Murdoch , Hervé Ménard , Ahmed Umar , Anders J. Barlow , Peter J. Cumpson , John T. S. Irvine , Ian S. Metcalfe

Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the underlying perovskite upon oxidation. Instead, they may remain pinned to their initial locations, allowing one to subject them to further chemical transformations to alter their composition, structure and functionality dramatically, while preserving their initial spatial arrangement. We refer to this concept as chemistry at a point and illustrate it by tracking individual nanoparticles throughout various chemical transformations. We demonstrate its remarkable practical utility by preparing a nanostructured earth abundant metal catalyst which rivals platinum on a weight basis over hundreds of hours of operation. Our concept enables the design of compositionally diverse confined oxide particles with superior stability and catalytic reactivity

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