There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Reverse osmosis desalination: Water sources, technology, and today's challenges

Direct And Mediated Anodic Oxidation of Organic Pollutants

Removal of heavy metal ions from wastewater by chemically modified plant wastes as adsorbents: A review

Microbial and plant derived biomass for removal of heavy metals from wastewater.

Treatment of tannery wastewater by chemical coagulation

Biosorption of lead, copper and zinc ions on loofa sponge immobilized biomass of Phanerochaete chrysosporium

Removal of coloured organic matter by adsorption onto low-cost waste materials

Biotechnology in the petroleum industry: An overview

Aquabacterium commune, a predominant member of European drinking water biofilms, was chosen as a model bacterium to study the role of functional groups on the cell surface that control the changes in the chemical cell surface properties in aqueous electrolyte solutions at different pH values. Cell surface properties of A. commune were examined by potentiometric titrations, modeling, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. By combining FTIR data at different pH values and potentiometric titration data with thermodynamic model optimization, the presence, concentration, and changes of organic functional groups on the cell surface (e.g., carboxyl, phosphoryl, and amine groups) were inferred. The pH of zero proton charge, pH(zpc) = 3.7, found from titrations of A. commune at different electrolyte concentrations and resulting from equilibrium speciation calculations suggests that the net surface charge is negative at drinking water pH in the absence of other charge determining ions. In situ FTIR was used to describe and monitor chemical interactions between bacteria and liquid solutions at different pH in real time. XPS analysis was performed to quantify the elemental surface composition, to assess the local chemical environment of carbon and oxygen at the cell wall, and to calculate the overall concentrations of polysaccharides, peptides, and hydrocarbon compounds of the cell surface. Thermodynamic parameters for proton adsorption are compared with parameters for other gram-negative bacteria. This work shows how the combination of potentiometric titrations, modeling, XPS, and FTIR spectroscopy allows a more comprehensive characterization of bacterial cell surfaces and cell wall reactivity as the initial step to understand the fundamental mechanisms involved in bacterial adhesion to solid surfaces and transport in aqueous systems.

Characterization of the Cell Surface and Cell Wall Chemistry of Drinking Water Bacteria by Combining XPS, FTIR Spectroscopy, Modeling, and Potentiometric Titrations

Robert G. J. Edyvean

Papers

Treatment of tannery wastewater by chemical coagulation

Biosorption of lead, copper and zinc ions on loofa sponge immobilized biomass of Phanerochaete chrysosporium

Removal of coloured organic matter by adsorption onto low-cost waste materials

Biotechnology in the petroleum industry: An overview

Characterization of the Cell Surface and Cell Wall Chemistry of Drinking Water Bacteria by Combining XPS, FTIR Spectroscopy, Modeling, and Potentiometric Titrations