Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/23219
Title: A comparative study of Low-cost biomaterials for the removal of chromium (VI/III) from aqueous solutions
Authors: SYAM KUMAR PRABHAKARAN
Keywords: Chromium, aqueous solutions, seaweeds, waste, tea, coffee
Issue Date: 8-Jun-2007
Source: SYAM KUMAR PRABHAKARAN (2007-06-08). A comparative study of Low-cost biomaterials for the removal of chromium (VI/III) from aqueous solutions. ScholarBank@NUS Repository.
Abstract: The contamination of water by toxic heavy metals including chromium is a worldwide problem. The release of chromium into the environment has become a seroius health problem due to its toxicity. Increasingly strict discharge limits on chromium have accelerated the search for highly efficient yet economically attractive or alternative treatment methods for its removal. The use of low-cost and waste biomaterials as adsorbents of dissolved metal ions has shown potential to provide economic solutions to this global environmental problem. Numerous studies on metal biosorption by brown seaweeds such as Sargassum have been reported. However the applicability of green seaweeds such as Ulva has not been extensively investigated yet for the removal of Cr(VI)/Cr(III), despite of its large abundance in the natural environment. In this study, laboratory scale investigations were conducted to compare the adsorption capabilities of Ulva with Sargassum for the removal of both Cr (VI) and Cr(III) from aqueous solutions. Various chemical pre-treatment methods were investigated for enhancing the adsorption capacity of both Sargassum and Ulva together with the use of other low cost waste biomaterials such as used tea and coffee dust. The most influencing adsorption parameters such as initial pH, quantity of adsorbent, initial metal ion concentration and contact time were studied for Sargassum, Ulva, used tea and coffee dusts. The adsorption capacity of Ulva was lower compared to that of Sargassum. The removal of hexavalent chromium by seaweeds was observed as a process of adsorption together with reduction by different kinetic rates. Ulva biomass only reduced less than 20% of the available Cr(VI) ions compared to a 100% reduction by Sargassum. However, Ulva and Sargassum have shown similar adsorption capacities for the removal of Cr(III) ions. Experiments were conducted by using an external reducing agent to speed up the reduction process by which an enhancement in the adsorption of Cr(VI) by Ulva biomass could be achieved. Domestic wastes such as used tea and coffee dusts have been found to be a strong anit-oxidant and be able to reduce more than 90% Cr(VI) ions to Cr(III) ions within an hour. Adsorption experiments showed that used tea and coffee dusts are not only good anti-oxidants, but also potential adsorbents which have a better adsorption capacity than Sargassum.
URI: http://scholarbank.nus.edu.sg/handle/10635/23219
Appears in Collections:Master's Theses (Open)

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