Browsing by Author "Premasinghe, Niroshan"

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    Graphite oxide coated sand composites for efficient removal of calcium ions from hard water: isotherm, kinetics, and adsorption mechanism
    (Polish Ministry of Science, 2024) Perera, W.P.R.T.; Premasinghe, Niroshan; Fernando, W.S.K.; Perera, P.L.R.A.; Sandaruwan, Chanaka; Kumarasinghe, A.R.; Liyanage, Janitha A.
    Even if granular media filtration effectively reduces the turbidity of water, its limited surface functionalities and physical properties may constrain its ability to effectively remove critical contaminants from water. In our research, we successfully synthesized a new type of porous material – multiple coated GO/sand (M-GO/S) by integrating ordinary river sand with graphite oxide (GO) for the adsorptive removal of calcium ions in terms of water softening. Prior investigations confirmed it could remove water turbidity and fluoride simultaneously. M-GO/S was characterized using microscopic and spectroscopic techniques. The results indicate the presence of an uneven coating of graphite oxide, and the nanocomposite contains oxygencontaining functional groups. Under given conditions, the M-GO/S nanocomposite demonstrated remarkable efficacy in removing 75% of calcium ions (a higher removal percentage than commercial coal powdered activated carbon) from simulated hard water: pH 8, 5.0 g dosage, 50 mg/L calcium ions, and 20 min contact time. The isotherm and kinetic data revealed that the adsorption mechanism primarily comprises multilayer adsorption by means of a chemical sorption process. The mechanism of the proposed M-GO/S nanocomposite for removing calcium ions from hard water is elucidated using (XPS) analysis. The presence of (-O-Ca-O-) chemical bonds on the surface of the nanocomposite after equilibration with calcium ions suggests the occurrence of chemical interactions between the calcium ions and oxygen-containing functional groups of the M-GO/S. Consequently, the synthesized M-GO/S nanocomposite can be identified as a promising candidate for hard water treatment.
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    Study of aqueous calcium ion adsorption competence by coreshell adsorbent granules engineered from sand/graphene oxide nanocomposite
    (Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Premasinghe, Niroshan; Perera, W. P. R. T.; Fernando, W. S. K.; Liyanage, Janitha A.; Kumarasinghe, A. R.
    In water treatment, sand unit processes are frequently used to remove turbidity. In order to enhanced the performance of the sand, a surface modification was done using graphite oxide. The core-shell granules were fabricated using graphite oxide coated river sand. Graphite oxide was derived from high purity vein graphite in Sri Lanka. Repeated coating of graphite oxide on the sand followed by low temperature (110 °C) thermal pyrolysis yield hierarchical core-shell structure where several layers of graphite oxide covered the sand particulates. Mineralogical and physicochemical characterization of the novel adsorbent was carried out by Energy Dispersive X-Ray attached to Scanning Electron Microscopy (SEM-EDX), Fourier-Transform Infrared Spectrometry (FTIR), and X-ray Powder Diffraction (XRD). The operational parameters such as contact time, initial calcium ion concentration, adsorbent dose and initial pH of the solution were evaluated in batch procedures at room temperature (26±2 °C) using Five time GO/sand combination which observed as the most effective combination for calcium ion removal from hard water. Characterization studies reveal that uneven coatings of graphene oxide present on the surface of Nanocomposite is containing oxygen-based functional groups (C-O, C=O, O-H) in addition to C-C groups. Optimization studies showed that, the most effective dosage of the adsorbent is 5.0 g with initial calcium ion concentration 50 mg/L. It appears that there was no significant effect on the calcium ion removal over a wide range of pH 4-10 and the process began to reach equilibrium after 20 minutes. Finally, super sand granules show high partiality towards calcium ions and it will be important for the treatment of the hard water and the multiple coated GO/sand combination can be used to regulate excess water calcium and turbidity simultaneously.