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Studies on removal of colour from waste water

Kini, Srinivas M (2014) Studies on removal of colour from waste water. Phd. Thesis thesis, Manipal Institute of Technology, Manipal.

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Fresh water is already a limiting resource in many parts of the world and it will become even more limiting in coming years due to increased population, urbanization, and climate change. Many industries like the textile, leather, paper, plastic, food technology industry use dyes to color their products and thus produce wastewater containing organics with a strong color. Color is the first contaminant to be recognized in wastewater. The presence of very small amount of dyes in water of less than 1 mg/ L is highly visible and undesirable. The colored wastewater effects aquatic systems and can cause severe damage to human health Wastewater containing dyes is very difficult to treat, since the dyes are recalcitrant organic molecules, resistant to aerobic digestion, and are stable to light, heat and oxidizing agents. The treatment of recalcitrant and toxic dyes with traditional technologies is not always effective or may not be environmentally friendly. Amongst the numerous techniques of dye removal, adsorption is the procedure of choice and gives the best results as it can be used to remove different types of coloring materials. Activated carbon is perhaps the most widely used adsorbent but is prohibitively expensive. Recently, attentions have been focused on the development of low-cost adsorbent for the application of wastewater treatment From a thorough literature study it was found that no work has been carried out describing the potential of Palm tree male flower(PTMF) and activated carbon prepared from PTMF for removal of any dye from aqueous solution. Also the evaluation of Benteak wood sawdust for adsorption of MB dye has not been reported so far. Apart from the primary reason mentioned above, the plant waste - PTMF, PTMFAC and ASD were specifically used in this work because of their abundance and low cost In this work the potential of PTMF, PTMFAC, ASD and A.niger as adsorbents were systematically evaluated by conducting batch studies involving process parameters such as pH, adsorbent dosage, initial dye concentration and temperature for MB dye removal. The adsorption data were fitted using well known isotherms. Results of this batch equilibrium experiments showed that Langmuir isotherm fitted very well to the experimental data for all the adsorbents with the highest monolayer adsorption capacity of 588.25 mg/g obtained for PTMFAC . Further the adsorption capacity was found to be in the order: PTMFAC > ASD > PTMF > A.niger. A new mathematical model was derived for adsorption of MB dye from the bulk onto the surface of the adsorbents and using this model the values of liquid phase diffusivity and external mass transfer coefficient were estimated. The mathematical model derived gave a satisfactory fit of model prediction and experimental data thereby indicating that majority of the adsorption is only taking place on the surface of the adsorbent with very less intraparticle diffusion Fixed bed adsorption experiments with MB were performed using immobilized A. niger beads, PTMF, PTMFAC and ASD . Breakthrough curves obtained from these column experiments were used to understand and predict the dynamic behavior of fixed bed adsorber with the above adsorbents. An unidimensional mathematical model was developed to represent the adsorption process on the fixed bed column and the solution was obtained by method of finite difference. The model was validated through the breakthrough data obtained by fixed bed adsorption experiments. Generally, very good agreement was obtained between the model simulated results and experimental breakthrough profiles

Item Type: Thesis (Phd. Thesis)
Subjects: Engineering > MIT Manipal > Chemical
Depositing User: MIT Library
Date Deposited: 30 Apr 2016 15:10
Last Modified: 30 Apr 2016 15:10

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