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    Optimization of pH, sorbent dose, and contact time in biosorption of Cu, Cd and Pb in sugarcane bagasse in a tri-metal aqueous system
    Abetria, Pauline Grace R. (Department of Chemistry, College of Arts and Sciences, Univsersity of the Philippines Visayas, 2013-04)
    Adsorption is one of the physicochemical treatment processes found to be effective in removing heavy metals from aqueous solutions. The biosorption of Cu, Cd, and Pb in sugarcane bagasse in a tri-metal aqueous system was optimized for pH, sorbent dose, and contact time using Doehlert design and it was found that the optimal values are pH 5, a sorbent dose of 1.33g sorbent/mg metal, a contact time of 4 hours, and the available sites on the sorbent for metal binding were influenced by pH. Furthermore, the effect of initial metal concentration on the metal uptake of the sorbent was also studied and it was found that at increasing metal concentrations the metal uptake also increased at a fixed (optimum) sorbent dose. The sorbent affinity was observed to be increasing in favor of increasing ionic radius, Cu < Cd < Pb, at relatively low metal concentrations and Cd < Cu < Pb at relatively high metal concentrations. Each metal behaved differently on the sorbent. Copper obeyed the Langmuir isotherm whereas cadmium and lead both obeyed the Freundlich isotherm. Finally, the IR spectrum of the sorbent was elucidated and -OH and -COOH groups were present but complexation was absent. Hence, in a tri-metal aqueous system containing Cu, Cd and Pb, the biosorption process in bagasse is proposed to be by physical adsorption.
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    Biosorption of Copper (CU) and Lead (PB) by heavy metal-resistant bacterial isolates from Iloilo River
    Ampuan, Naira Mitz W. (Division of Biological Sciences, College of Arts and Sciences,University of the Philippines Visayas, 2012-04)
    Many indigenous organisms isolated from sites contaminated with heavy metals have tolerance to heavy metal toxicity and these microbial activities have always been the natural starting point for all biotechnological applications. It is therefore necessary to isolate bacterial strains with novel metabolic capabilities. In this study, a total number of 18 heavy metal-resistant bacteria (10 Pb-resistant and 8 Cu-resistant) were isolated from Iloilo River sediment samples (10° 41.974’N, 122°34.187’ E). Biosorption of Cu and Pb by the bacterial isolates was characterized to evaluate their applicability for heavy metal removal from industrial waters. Selecting the highest resistance to metal toxicity’ and biosorption, 4 isolates were identified by phenotypic characterization. Identification of the top four metal-resistant isolates designates: Vibrio charchariae (83%) for Cu4; Vibrio harveyi (79%) for Cu6; Moraxella equi (100%) for Pb8; and Phoecoenobacter uteri (92%) for Pb9. Evaluation of specific metal biosorption by the isolates after incubation for 48 h suggested that none of the isolates have good potential for bioremoval of metals from contaminated environments.