Browsing by Author "Sufiani,Omari"

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    Performance evaluation of sodium super ionic conductors for enhanced brackish water desalination by capacitive deionization.
    (NM-AIST, 2025-07) Sufiani,Omari
    This study reports on the synthesis, characterization and application of sodium superionic conductors for water desalination by Capacitive deionization (CDI).The Sodium super ionic conductors (NASICONs) outperform carbon-based adsorbents and most battery electrodes due to their 3D bulk ion storage, exceptional ionic conductivity and strong structural stability.Variable synthesis conditions were applied namely the number of sulphate ions substituted for phosphates in Na3Fe2(PO4)3 (NFP) and mass ratios of activated carbon (AC)/NFP to prepare NaFe2PO4(SO4)2/C (NFPS/C) and AC/NFP composites respectively. Several characterization techniques such as X-ray diffraction, scanning electron microscopy, Transmission electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption measurements and X-ray photoelectron spectroscope confirmed the synthesized materials. Characterization results show that the N2 adsorption-desorption isotherms of AC/NFP composite is of type III, suggesting slit shaped pores due to accumulation of flake shaped particles. The X-ray diffraction analysis revealed NFPS/C to exhibit orthorhombic structure while AC/NFP had monoclinic crystal system. The scanning electron micrographs revealed the particles of both NFPS/C and AC/NFP composite less aggregated. Due to less aggregated particles of NFPS/C observed in SEM micrographs it was used in CDI wherein, the salt removal capacity increases with the solution concentration, desalination duration and applied potential. Further, experiments involved desalination of Indian Ocean water solutions diluted several times to achieve the concentration of solution resembling permeates produced by seawater reverse osmosis (SWRO) which is attained by water samples diluted one hundred times (487 µS/cm). The salt removal capacity for desalination of Indian Ocean water samples not diluted and diluted hundred times was about 27.3 and 10.6 mg/g, respectively. Further CDI tests involved comparing the salt removal capacity of the AC and AC/NFP composites wherein, much higher performance of around 22.0 was attained by AC/NFP 1:2 against 18.65 mg/g of AC. The improved performance of AC/NFP 1:2 composite might be due to its high specific surface area and the enhanced interfacial contact between the composite and the salt solution. These results demonstrate that NASICONs present a viable strategy for improving desalination efficiency of a CDI system.