Browsing by Author "Gunathilake, C.A."

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    Removal of Heavy Metals from Industrial Wastewater through Minerals
    (Uva Wellassa University of Sri Lanka, 2019-02) Muthukalum, U.A.S.L.; Gunathilake, C.A.
    Heavy metals are toxic to health and environment and causes harmful outcomes to the human beings. It is essential to take effective endeavors to remove the metals from contaminated water. In this research, naturally available brick materials with different compositions collected from Kandy (type A), Gampaha (type B), and Embilipitiya (type C) areas were used to remove Cu, Cr and Pb ions. These brick materials are cost effective and readily available alternative to conventional heavy metal removal. The characterization of brick materials is performed using X-Ray Fluorescence (XRF) and Nitrogen Adsorption – Desorption analyser. Calculated surface area and total pore volume and pore width of type A, B, and C are lie respectively, in the range of 128-154 m2/g, 0.24-0.45 cm3/g, and 5.6-16.7 nm. Main objective of this research is to investigate how the characteristics of adsorbents influence the adsorption process and identifying the best model to describe the kinetic and equilibrium adsorption to purify the metal contaminated water. Results indicate that Pseudo – first – order kinetics model properly described the adsorption of Cu2+ to the brick type C, which has maximum adsorption capacity of 497 mg g-1. The adsorption process of Pb2+ to the brick type A and Cu2+ and Pb2+ to brick type B and C were well-fitted with Pseudo – second – order kinetics model. In equilibrium studies, Langmuir isotherm showed a better fitness in adsorption of Cu2+ into brick type A and C, Pb2+ into brick type B, whereas Freundlich isotherm well represented the adsorption characteristics of Cu2+ into brick type A, Pb2+ into brick type B and Cr6+ into all brick types. The comparison results indicate that the use of brick types A, B, C can be used as potential nan sorbents to remove heavy metals from industrial waste waters.
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    Synthesis of Calcium Carbonate Nano Particles using Citrate Method to Remove Dyes from Textile Waste Water
    (Uva Wellassa University of Sri Lanka, 2019) Fernando, B.D.A.S.; Gunathilake, C.A.; Karunaratne, D.G.G.P.
    Dye removal is an important aspect as textile industries produce waste water containing high amounts of textile dyes at high temperatures. Therefore purification of the textile waste water is of great importance as the treated water would be discharged into natural water streams. Using nanomaterials, dye removal has been studied and have yielded promising results. In this study, nano-sized calcium carbonate were synthesized using Solgel hydrothermal citrate method. Calcium nitrate, citric acid and sodium hydroxide were used as precursors for the method. Using different concentration of citric acid solution, selected as 0.5, 1, 1.25 and 2.5 times of the calcium nitrate solution, calcium carbonate nanoparticles were synthesized. X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transformed Infrared Spectroscopy (FT-IR), Thermo gravimetric analysis (TGA) and N2 adsorption-desorption analysis were conducted (to characterize the synthesized nanoparticles qualitatively and quantitatively). For testing adsorption of the synthesized nanoparticles, standard methylene blue dye solutions were prepared and used. The effect of initial dye concentration, pH (7-12), temperature (35 °C, 45 °C, 55 °C) were conducted in this study. Optimum pH value and temperature for maximum dye adsorption were obtained. With increasing pH and temperature, adsorption capabilities increased significantly. Equilibrium data was well fitted with Langmuir isotherm for the effect of initial dye concentration. Adsorption data were used for kinetic studies using pseudo first order and second order rate equations. Kinetic studies conducted for pH was well fitted with pseudo second order rate equation, while the kinetic studies conducted for temperature was well fitted with pseudo first order rate equation. Considering the results, synthesized calcium carbonate nanoparticles could be used as an alternative for dye adsorption.
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    Synthesis of Graphene Oxide from Graphite for Water Treatment
    (Uva Wellassa University of Sri Lanka, 2019-02) Samarathunga, D.N.; Gunathilake, C.A.
    Carbon containing materials are typically used as an adsorbent for water treatment, specially to remove heavy metals, toxic anions, and dye stuffs. In this research, graphene oxide is synthesized from graphite using modified Hammers method for lead removal application. Synthesized grapheme oxide is identified by high resolution thermogravimetric (HR-TGA) studies where graphene oxide tends to decompose in the temperature range of 570-640 oC. Surface properties of graphene oxide including the specific surface area, total pore volume, pore width, single point pore volume, microporous volume is measured by using nitrogen adsorption desorption analyzer at- 196 oC using liquid nitrogen and calculated those properties using KJS (Kruk Jaroniec, Sayari) method. Total pore volume, specific surface area, pore width, single point pore volume, microporous volume of graphene oxide, respectively, are ~ 0.24 cm3 g-1, 41 m2 g-1, 7.6 nm, 0.22 cm3 g-1, and 0.01 cm3 g-1. Synthetic lead solutions are used to study the adsorption and kinetic behavior of graphene oxide. Lead ion concentration are measured using atomic adsorption spectrophotometer. Kinetic sorption reveals that 2-3 hour is required to achieve the equilibrium condition. Graphene oxide adsorption process is well fitted with pseudo-second-order kinetic model than pseudo-second-order showing regression coefficient value (R2) of 0.9991 and reached to the adsorption capacity of 100 mg g-1.