Browsing by Author "Ekanayake, E. M. M. S."

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    Development of low-cost automated robot arm; its limitations and the validity of results through modified potentiometric experiments
    (Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, K. A. N. K.; Rodrigo, S.; Liyanage, I.; Umayanga, I.; Perera, B.; Nawarathne, D.; Perera, D.; Jiffry, N.; Sirimuthu, N.; Ekanayake, E. M. M. S.
    Robotics is used widely in design, construction and operation, further also in control, sensory, feedback and information processing. Robotics arm performs a crucial task in all the above. Automation in a chemical laboratory will be a major breakthrough in terms of productivity, quality and the reproducibility of the results, improved safety, reduce the time and cost of the whole running process. To catalyze this revolutionized system performances, as a combination of engineering and chemistry, we developed an automated robot arm and validated its results while overlooking the limitations via modified potentiometric experiments. The idea behind this concept is to use this robotics hand in places where it can be used to replicate the action of a human hand and thereby substituting its purpose in places where a human hand cannot be used. During this experiment robot arm involved in measuring cell voltage by using a standard calibrated potentiometer in a thermostat water bath at different temperatures; where it produced steady results compared to the manual procedure under same conditions while saving a considerable working time. The potentiometric reading equipment IEEE 488 fitted with an Interface Scanner 740 and a GPIB (General Purpose Interface Bus) program was used to obtain a continuous record of the potentials while test solutions were moving on a belt. For the validation, reading taken by using the automated arm and manual readings for the same sample were statistically analyzed (n=181) using t-test, linear regression and Spearman correlation coefficients which clearly indicate no significant difference between them. In summary, this work described an inexpensive and simple method for the automated potentiometric titration. The only limitation encountered during this process was the servo motors used, have only a maximum rotation of 180⁰ for 1m radius semicircle within 75s. Therefore, the area of movement is restricted to a certain region of space, but the arm can move an object from one-point coordinate to another in the x, y and z axes which could be adapted to many applications other than in a chemical lab.
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    Isolation of laccase producing fungi: Aspergillus niger from Sri Lankan textile wastewater effluents and its potential applicability on decolorization of an azo dye: CI Direct Blue 201
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Ekanayake, E. M. M. S.; Wijesekara, I.; Manage, P.M.
    The complex aromatic structural nature of synthetic dyes show resistance to natural oxidation processes and persist in the surface water and sediments for a long time. The existing physical and chemical treatment methods are costly and create secondary pollution. Therefore, the present study was focused on the degradation of an azo dye: CI Direct Blue 201 (DB 201), by myco-remediation. Aspergillus niger, a filamentous fungus, was isolated from textile wastewater effluent site in Sri Lanka and pure cultures were maintained on Potato Dextrose Agar (PDA) plates. Four cylinders (10 mm diameter in each) of actively growing A. niger cultures were cut and inoculated into mineral salt medium consisted of 50 mgL-1 DB 201 dye. All the experiments were carried out in triplicates, while controls were maintained without addition of the fungus. Flasks were incubated at 28 °C for seven days with shaking at 100 rpm. Three milliliters of sample aliquots were removed at 6 hrs intervals, centrifuged and the changes of the absorbance in the supernatant was analyzed through UV-Vis spectrophotometer at 570 nm. The laccase activity was determined by measuring the increase in the optical density at 420 nm. The reaction mixture for laccase assay contained 5 mM of 2,20-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) in 50 mM sodium acetate buffer (pH 4.5) and 50 μL of decolorized dye solution (ε420 = 36000 M−1 cm−1). Decolorized dye sample was analyzed through Fourier Transform Infrared (FTIR) Spectroscopy. A Bio-sorption test was carried out by providing the same incubation conditions using 3-day-old live and autoclaved fungi. The control without adding fungus, remained the same without showing any decolorization. The enzyme activity of laccase has increased during the decolorization processes from 18 Uml-1 to 254 Uml-1. The changes of the FTIR spectra relevant to the N=N Vibration (1723.3 cm-1), S=O Stretching (1227.3 cm-1) and N-O Stretching (742.88 cm-1) indicated the changes of the initial DB 201 dye structure after the treatment by A. niger. Furthermore, the bio-sorption assay by live (100%) and autoclaved fungi (12 ± 2%) confirmed the decolorization and the degradation of DB 201 dye would be based on the metabolic activity of the fungus rather than surface adsorption. Therefore, the present study emphasizes the potency of A. niger as an eco-friendly candidate for degradation of azo dyes. Further studies regarding the application of enzymes for real textile dye treatments are currently in progress.