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Item Bench scale fixed-bed column adsorption studies and adsorption modelling: removal of methylene blue from aqueous solutions using glutaraldehyde cross - linked chitosan beads(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Amarasooriya, M. P. N. A.; Rajapakse, C. S. K.As dye-containing waste effluent is a big threat not only to the environment, but also to human life and the economical removal of dyes from wastewater has become an environmental challenge in nowadays. Therefore, this work focuses on the exploration of potential of using physically and chemically modified chitosan, glutaraldehyde cross-linked chitosan beads (GCLCBs) to remove a model dye, methylene blue (MB) from aqueous solutions using bench-scale fixed bed columns. GCLCBs (4.00±0.02 mm in diameter) were prepared by using glutaraldehyde as the cross-linking agent and it was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). FTIR analyses confirmed the cross-linking of chitosan beads with glutaraldehyde. The effects of initial MB concentration (10, 12, 15 mg/L) and inlet flow rate (5, 10, 15 mL/min) at neutral pH and at room temperature (30 ± 2 ºC) on the performance of column packed with GCLCBs were analysed using breakthrough curves. The breakthrough time (Tb), time required for full bed exhaustion (Tt), bed capacity (BC) and length of unused bed (LUB) were determined at each column operating conditions. The highest % MB removal of 72.80% was obtained at initial MB concentration of 10 mg/L and inlet flow rate of 5 mL/min at 6 cm bed height of the adsorbent. The breakthrough time, Tb increased with decreasing inlet flow rate and initial MB concentration. Two kinetic models namely the Thomas model and Yoon – Nelson model were used to predict the column performance and column parameters important in designing large-scale columns in water purification systems. The results revealed that the Thomas rate constant decreased with increasing initial adsorbate concentration and inlet flow rate. The time required to achieve 50% of adsorbate breakthrough (τ) seems to agree quite well with the experimental data (τ experimental) according to the results obtained from Yoon – Nelson model. Both the Thomas and Yoon – Nelson models fitted the experimental data with high regression coefficient values (R2 ~ 1) indicating the validity of both kinetic models for the studied column system. Based on the results it can be concluded that that the GCLCBs could be used as low-cost and environmentally friendly agent for the treatment of dye containing wastewaterItem An investigation of the adsorption of dye (Bromothymol Blue) by Sri Lankan montmorillonite clay(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Premaratne, W.A.P.J.; Perera, V.M.Textile industries use dyes and pigments to color their products and thus produce wastewater containing organics with a strong color. However most of the synthetic dyes used in textile industry usually composed of aromatic structure, which makes them carcinogenic and mutagenic and non-biodegradable when discharged into waste streams. The removal of such colored agents from aqueous effluents is of significant environmental, technical and commercial importance. Clay has been accepted as one of the appropriate low cost adsorbents for removal of dyes from wastewater. Among the clay types montmorillonite has received considerable recognition because of its high adsorption capacity due to their lamellar structure which provides higher specific surface area and possibility to adsorb ions and other polar organic molecules on particle external site and in interlayer positions. In this study the adsorption of basic dye: Bromothymol blue (BTB) from aqueous solution by Sri Lankan montmorillonite was investigated. Montmorillonite clay used in this investigation was obtained from Murunkan clay deposit in Sri Lanka. Montmorillonite clay was examined for its performance as an adsorbent for the BTB removal. The effect of key operational parameters, such as contact time, initial dye concentration, adsorbent dosage, stirring rate and temperature were experimentally studied. Adsorption of BTB onto montmorillonite samples was studied by batch adsorption technique at 30±1 ºC using UV-Visible spectrophotometric method. For the BTB initial concentration of 70 ppm with the use of only 20 g/L of montmorillonite clay, the dye removal efficiency was found to be 63%. The equilibrium data was analyzed using Langmuir and Freundlich adsorption isotherms. Langmuir isotherm provided a better fit to the data. Characterization of clay before and after the adsorption was carried out by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. XRD, FTIR and SEM data revealed that the dye did not penetrate in to the interlayer space of clay fully, but rather adsorbed on external surface by forming hydrogen bonding with the dye molecules creating a void free film on the clay surface. Experimental results confirmed that the Sri Lankan montmorillonite clay is an efficient adsorbent for basic dye removal. Therefore, Sri Lankan montmorillonite can be used as a promising low cost alternative adsorbent for removing basic dyes from dye wastewater.