Research Publications

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Open Access
Kinetics and Thermodynamics Study of Methylene Blue Adsorption to Sucrose- and Urea-Derived Nitrogen-Enriched, Hierarchically Porous Carbon Activated by KOH and H3PO4
(American Chemical Society, 2023-04-27) Liyanaarachchi, H; Thambiliyagodage, C; Lokuge, H; Vigneswaran, S
Hierarchically porous nitrogen-enriched carbon materials synthesized by polymerization of sucrose and urea (SU) were activated by KOH and H3PO4 (SU-KOH and SU-H3PO4, respectively). Characterization was undertaken and the synthesized materials were tested for their ability to adsorb methylene blue (MB). Scanning electron microscopic images along with the Brunauer−Emmett−Teller (BET) surface area analysis revealed the presence of a hierarchically porous system. X-ray photoelectron spectroscopy (XPS) confirms the surface oxidation of SU upon activation with KOH and H3PO4. The best conditions for removing dyes utilizing both activated adsorbents were determined by varying the pH, contact time, adsorbent dosage, and dye concentration. Adsorption kinetics were evaluated, and the adsorption of MB followed second-order kinetics, suggesting the chemisorption of MB to both SU-KOH and SUH3PO4. Times taken to reach the equilibrium by SU-KOH and SU-H3PO4 were 180 and 30 min, respectively. The adsorption isotherm data were fitted to the Langmuir, Freundlich, Temkin, and Dubinin models. Data were best described by the Temkin isotherm model for SU-KOH and the Freundlich isotherm model for SU-H3PO4. Thermodynamics of the adsorption of MB to the adsorbent was determined by varying the temperature in the range of 25−55 °C. Adsorption of MB increased with increasing temperature, suggesting that the adsorption process is endothermic. The highest adsorption capacities of SU-KOH and SU-H3PO4 (1268 and 897 mg g−1 , respectively) were obtained at 55 °C. Synthesized adsorbents were effective in removing MB for five cycles with some loss in activity. The results of this study show that SU activated by KOH and H3PO4 are environmentally benign, favorable, and effective adsorbents for MB adsorption.
Open Access
Development of Silica-Copper Nanocomposite for Water Purification
(SLIIT, 2022-02-11) Angappan, S; Karunaratne, M; Thambiliyagodage, C
Water pollution is one of the serious concerns across the world at the moment. Industrial wastewater significantly contributes to the negative impacts caused by water pollution. Textile industries discharge large amounts of effluents into water streams with little or no treatment of the discharge because wastewater treatment is an expensive process. Thus, there exists a need for a cheap and effective way to treat textile effluent that contains dyes before being discharged. A high purity silica-based Nano-adsorbent was synthesized by using rice husk as the commercially available main cheap precursor. Copper-loaded silica nanoparticles were successfully functionalized with 3-aminopropyl triethoxysilane (APTES) via the sol-gel pathway to enhance the adsorption performance of organic dyes from textile effluent. The performance of produced Nano-adsorbent was evaluated by using methylene blue as waste adsorbate. As synthesized nanomaterial was characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy, the XRD results confirmed the presence of silicon dioxide (SiO2) and paramelaconite (Cu4O3) as predicted. The FTIR confirmed the presence of Si–O stretching, N-H bending, C–H stretching, Cu–O stretching and O–H bending vibrations thereby suggesting the presence of SiO2, NH2 groups, CH2, Cu4O3 and physisorbed H2O. The optimum conditions for pH and adsorbent dosage were successfully evaluated for the adsorption process. The optimum pH at which the nanomaterial performed best was at pH 4. The optimum mass of the adsorbent that gave maximum adsorption performance was 20 mg. Kinetic studies revealed that the experimented data was in better correlation with pseudo-second-order kinetics. The outcome of this project would be of interest to textile industries looking for a cheap and effective way to treat textile wastewater

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