Browsing by Author "Sandaruwan, Chanaka"

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    Anti-microbial Nanohybrids Based on Naturally Derived Citric Acid Intercalated Layered Double Hydroxides
    (Kuruppu et al/ Current Scientia, 2021) Kuruppu, Shashikala; Rathnayake, Upendra; de Silva, Madhavi; Rupasinghe, Thilini; Sandaruwan, Chanaka
    Currently, there is an increased demand for advanced food packages, which can significantly increase the shelf life of food items. In the current context, it is envisaged that nanotechnology has the potential to address stability, toxicity, shelf-life, and low-cost issues of antimicrobials associated with the packaging industry. Antimicrobial nanocomposite systems are believed to be more efficient than their microscale counterparts due to the high surface area to volume ratio and quantum mechanical involvement in deciding their properties. As a result of high surface area, they are able to attach more copies of microbial molecules and cells, thus reducing the quantity of material required while significantly improving their activity. This study focuses on the development of slow-release antimicrobial material based on natural citrate (α-hydroxycitrate) intercalated layered double hydroxide (LDH) nanohybrid. Natural citrate ions available in Citrus aurantifolia (lime) were extracted by a simple chemical method and intercalated into Mg-Al-Layered Double Hydroxide following a one-step co-precipitation method. Successful intercalation of the citrate ion was confirmed by powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopic analysis. Release kinetics of resulted nanohybrid was studied and compared using different release kinetic models. Antimicrobial properties of this novel nanohybrid were confirmed against two common food pathogens, Colletotrichum gloeosporioides and Saccharomyces cerevisiae, and the results were compared against sodium benzoate, which is the commonly used commercial antimicrobial agent in the food industry. Successful intercalation of natural citrate ions into LDH and its activity against the tested microbes show the potential of using it as a slow-release nanohybrid material in many food-related applications.
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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.