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The present study explores the microstructural characteristics and electrochemical responses of different TiMoZrTa alloys designed for biomedical implantation. The alloys corrosion resistance (potentiodynamic polarization and electrochemical impedance spectroscopy) was determined in acidified Ringer's solution at 37 °C. The pH was adjusted to 3.6 in order to reproduce the pathological state. The new materials formed spontaneously a passivation oxide film on their surface, and they remained stable for polarizations up to +1.0 VSCE. No evidence of localized breakdown of the oxide layers was registered even when higher positive polarizations than those encountered in the human body were applied.

In this study, the adsorption of Pb2+ and Zn2+ ions from aqueous solutions onto lignin obtained from unmodified Sarkanda grass was analyzed. To ensure optimal process conditions, the retention of lead and zinc ions was tested at different experimental parameters (pH of the initial solution and adsorbent, the dose of adsorbent, the concentration of aqueous solutions and contact time). The experimental results have been interpreted using the classic Langmuir and Freundlich isotherm models, as well as two kinetic models (the Lagergren pseudo-first order and the Ho and McKay pseudo-second order models). Based on the analysis of the experimental data, it has been concluded that unmodified Sarkanda grass lignin can be recommended as an efficient alternative, considering its practical applicability, in the retention of Pb2+and Zn2+ ions from aqueous solutions, both in terms of the amount of adsorbate and pollutant species retained, as well as in terms of adsorption time.

"Considering the negative effects of polluting species on the environment and human health, in particular heavy metals, and the need for efficient use of resources, the present study investigated the adsorption of As (III) from aqueous solutions under static conditions onto chemically unmodified Sarkanda grass lignin. In order to optimize the adsorption process, the retention of As (III) was tested under various experimental parameters (pH of the initial solution and adsorbent, concentration of aqueous solutions, adsorbent dose and contact time of the two phases). The experimental data obtained were interpreted based on the classical models of Freundlich and Langmuir isotherms, which was useful in establishing the equilibrium conditions and in evaluating the adsorption capacity for a solute. The adsorption dynamics was studied using the Lagergren pseudo-first order and the Ho and McKay pseudo-second order models. The analysis of the obtained experimental data recommends chemically unmodified Sarkanda grass lignin as a future alternative adsorbent for water remediation, taking into account its practical applicability in the retention of As (III) from aqueous solutions, in terms of both adsorbent and adsorbed doses, as well as the time required for adsorption. "

The degradation characteristics of hydroxyapatite-zirconia-silver films (HA-ZrO2-Ag) coatings on three ZrTi alloys were investigated in Ringer's solution containing 10% human albumin protein at 37 °C. Samples were immersed for 7 days while monitored by electrochemical impedance spectroscopy (EIS) and linear potentiodynamic polarization (LPP). The electrochemical analysis in combination with surface analytical characterization by scanning electron microscopy (SEM/EDX) reveals the stability and corrosion resistance of the HA-ZrO2-Ag coated ZrTi alloys. The characteristic feature that describes the electrochemical behaviour of the coated alloys is the coexistence of large areas of the coating presenting pores in which the ZrTi alloy substrate is exposed to the simulated physiological environment. The EIS interpretation of results was thus performed using a two-layer model of the surface film. The blocking effect in the presence the human albumin protein produces an enhancement of the corrosion resistance. The results disclose that the Zr45Ti alloy is a promising material for biomedical devices, since electrochemical stability is directly associated to biocompatibility.