Maria de Fátima Brito Sousa

New methodology based on static light scattering measurements for evaluation of inhibitors for in bulk CaCO3 crystallization.

In the present work a new procedure for evaluation of scale inhibitor for calcium carbonate is proposed based on continuous measurement of particle size distribution by laser diffraction technique and simultaneous pH recording. From data obtained during real-time monitoring of the homogeneous nucleation and growth of CaCO3 particles formed in the bulk phase after the addition of carbonate ions to synthetic formation water (AF-W2), it was possible to evaluate the performance of four inhibitors classified in two groups: phosphonates (ethylenediamine tetramethylene phosphonic acid, EDTMP; diethylenetriamine pentamethylene phosphonic acid, DETPMP) and polymeric inhibitors (phosphino poly carboxylic acid, PPCA; polyvinyl sulfonate, PVS). The comparative bulk crystallization inhibition efficiency for the evaluated inhibitors, under the experimental conditions used in this work, increases in the following order: EDTMP<DETPMP<PVS≅PPCA. Moreover, this methodology allowed the deduction of the main mechanism of their inhibiting action: nucleation inhibition or crystal growth retardation.

Obtenção de um material adsorvente para íons de metais pesados, através da eletropolimerização de 2-mercaptobenzimidazol à superfície de carbono vítreo reticulado

Electrochemical methods applied to organic species transformation has been used as excellent synthesis tools. C-C bonds can be established, making possible polymer synthesis by both anodic and cathodic reactions of suitable monomer species at the working electrode surface. In this study, anodic procedure was used to electropolymerization of 2-mercaptobenzimidazole at reticulated glassy carbon (RGC) surface. 2-mercaptobenzimidazole presents ligand sites towards Hg2+, Ag+ and Cu2+ ions. The obtained material has been able to adsorb the above mentioned ions in aqueous solution.

Non-equilibrium thermodynamic model for calcium carbonate supersaturated solutions of high salinity

Based on principles of non-equilibrium thermodynamics, the behavior of calcium carbonate supersaturated solutions of high salinity is studied. For this purpose, these solutions are treated as continuous media whose physicochemical properties change in space and time. Furthermore, by exploiting the Müller–Liu formulation for the second law of thermodynamics, one recognizes which thermodynamic forces are responsible for keeping the

An indirect voltammetric approach for the determination of cyanide at a chemically modified electrode

CaCO_{3}

Quartz Crystal Microbalance Evaluation of Inhibitors for Inorganic Scale

CaCO3 supersaturated solutions out of equilibrium. The obtained results suggest that intermolecular interaction forces play an important role in the dynamics of solution, as well as in the mass transport of solutes. Particularly, from the estimated values for the self-diffusion and mutual diffusion coefficients of NaCl(aq),

A two-fluid model for calcium carbonate precipitation in highly supersaturated solutions

CaCl_{2}(aq)