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Study of adsorption of citrate on Pt by CV and EQCM
(Elsevier, 2008-07-01) Gonzalez Peña, Omar Israel; Chapman, Thomas W.; Vong, Yunny Meas; Antaño-López, René; GONZALEZ PENA, OMAR ISRAEL; 162547; CIDETEQ; Instituto Tecnológico y de Estudios Superiores de Monterrey
Citrates are frequently used as additives in the electrodeposition of metals such as manganese in order to improve deposit characteristics and process efficiency. Nevertheless, few studies have been reported on the mechanism of citrate adsorption. This paper presents the results of a study of citrate adsorption onto platinum from solutions of various citrate concentrations in 0.1 M HClO4. Simultaneous observations with an electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry (CV) indicate that with increasing concentrations, up to 10−2 M, the fractional surface coverage by citrate rises to 13% in the region of hydrogen UPD, and the anodic formation of PtO is inhibited and reduced by as much as 43%. Combination of EQCM with cathodic linear-sweep voltammetry shows the interactions of citrate with platinum oxidation and hydrogen UPD. Thus, this approach reveals changes in additive adsorption with potential and indicates in particular the influence of the additive on the adsorption and desorption of hydrogen as a step in understanding metal deposition.
Protein adsorption through Chitosan–Alginate membranes for potential applications
(Springer Open, 30/04/2016) Murguía Flores, Dennise A.; Bonilla Ríos, Jaime; Canales Fiscal, Martha R.; Sánchez Fernández, Antonio; Tecnologico de Monterrey
Abstract Background Chitosan and Alginate were used as biopolymers to prepare membranes for protein adsorption. The network requires a cross-linker able to form bridges between polymeric chains. Viscopearl-mini® (VM) was used as a support to synthesize them. Six different types of membranes were prepared using the main compounds of the matrix: VM, Chitosan of low and medium molecular weight, and Alginate. Results Experiments were carried out to analyze the interactions within the matrix and improvements were found against porous cellulose beads. SEM characterization showed dispersion in the compounds. According to TGA, thermal behaviour remains similar for all compounds. Mechanical tests demonstrate the modulus of the composites increases for all samples, with major impact on materials containing VM. The adsorption capacity results showed that with the removal of globular protein, as the adsorbed amount increased, the adsorption percentage of Myoglobin from Horse Heart (MHH) decreased. Molecular electrostatic potential studies of Chitosan–Alginate have been performed by density functional theory (DFT) and ONIOM calculations (Our own N-layered integrated molecular orbital and molecular mechanics) which model large molecules by defining two or three layers within the structure that are treated at different levels of accuracy, at B3LYP/6-31G(d) and PM6/6-31G(d) level of theory, using PCM (polarizable continuum model) solvation model. Conclusions Finally, Viscopearl-mini® acts as a suitable support on the matrix for the synthesis of Chitosan–Alginate membranes instead of cross-linkers usage. Therefore, it suggests that it is a promise material for potential applications, such as: biomedical, wastewater treatment, among others. Graphical abstract Chitosan, Alginate, and Cellulose beads-based membranes for protein adsorption. Special attention was given for preparation, charaterization, adsorption capacity, and molecular electrostatic potential studies calculation. Viscopearl-mini® gives support on the matrix of Chitosan–Alginate membranes instead of cross-linkers usage

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