Bacterial biosorbents and biosorption

The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C–C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of...

Advances in Synthetic Applications of Hypervalent Iodine Compounds

Biosorption may be simply defined as the removal of substances from solution by biological material. Such substances can be organic and inorganic, and in gaseous, soluble or insoluble forms. Biosorption is a physico-chemical process and includes such mechanisms as absorption, adsorption, ion exchange, surface complexation and precipitation. Biosorption is a property of both living and dead organisms (and their components) and has been heralded as a promising biotechnology for pollutant removal from solution, and/or pollutant recovery, for a number of years, because of its efficiency, simplicity, analogous operation to conventional ion exchange technology, and availability of biomass. Most biosorption studies have carried out on microbial systems, chiefly bacteria, microalgae and fungi, and with toxic metals and radionuclides, including actinides like uranium and thorium. However, practically all biological material has an affinity for metal species and a considerable amount of other research exists with macroalgae (seaweeds) as well as plant and animal biomass, waste organic sludges, and many other wastes or derived bio-products. While most biosorption research concerns metals and related substances, including radionuclides, the term is now applied to particulates and all manner of organic substances as well. However, despite continuing dramatic increases in published research on biosorption, there has been little or no exploitation in an industrial context. This article critically reviews aspects of biosorption research regarding the benefits, disadvantages, and future potential of biosorption as an industrial process, the rationale, scope and scientific value of biosorption research, and the significance of biosorption in other waste treatment processes and in the environment. Copyright © 2008 Society of Chemical Industry

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Biosorption: critical review of scientific rationale, environmental importance and significance for pollution treatment

The marine algae Sargassum sp, Padina sp, Ulva sp, and Gracillaria sp, harvested locally, were investigated for their biosorption performance in the removal of lead, copper, cadmium, zinc, and nickel from dilute aqueous solutions It was found that the biosorption capacities were significantly affected by solution pH, with higher pH favoring higher metal-ion removal Kinetic and isotherm experiments were carried out at the optimal pH: at pH 50 for lead and copper, and at pH 55 for cadmium, zinc, and nickel The metal removal rates were rapid, with 90% of the total adsorption taking place within 60 min Sargassum sp and Padina sp showed the highest potential for the sorption of the metal ions, with the maximum uptake capacities ranging from 061 to 116 mmol/g for Sargassum sp and 063 to 125 mmol/g for Padina sp The general affinity sequence for Padina sp was Pb>Cu>Cd>Zn>Ni, while that for Sargassum sp was Pb>Zn>Cd>Cu>Ni XPS and FTIR analysis of Sargassum sp and Padina sp revealed the chelating character of the ion coordination to carboxyl groups It was confirmed that carboxyl, ether, alcoholic, and amino groups are responsible for the binding of the metal ions

Sorption of lead, copper, cadmium, zinc, and nickel by marine algal biomass: characterization of biosorptive capacity and investigation of mechanisms

Biosorption and bioaccumulation ― the prospects for practical applications

A culture of Arthrobacter sp. was tested for its ability to sorb copper, cadmium, and iron ions, and chemical modeling of experimental data was used to interpret the mechanism of biosorption. The purpose of the initial phase was to clarify the nature and concentration of active acidic sites on cell wall with the aid of potentiometric titration of an aqueous cellular suspension and IR analysis of the lyophilized biomass in solid phase. The experimental results showed that the cell wall probably has at least two weakly acidic sites. In the second part of the experimental work Arthrobacter sp. was suspended in the presence of copper, cadmium, and iron ion solutions at different equilibrium pH values. Adsorption isotherms were obtained by using an original procedure defined as the “subsequent additions method” (SAM). The results showed a strong influence of pH, especially over pH 5. A chemical model based on a possible set of reactions between ions in solution and the biomass has been developed. Mechanistic m...

M Trifoni

Papers

Biosorption of Metal Ions on Arthrobacter sp.: Biomass Characterization and Biosorption Modeling

Equilibrium biosorption studies in single and multi-metal systems

Shrinking core model with variable activation energy: A kinetic model of manganiferous ore leaching with sulphuric acid and lactose

Reductive leaching of manganiferous ores by glucose and H2SO4 : effect of alcohols

Acid leaching process by using glucose as reducing agent : A comparison among the efficiency of different kinds of manganiferous ores