Performance and Techno-Economic Analysis of Scaling-up A Single-Chamber Yeast Microbial Fuel Cell as Dissolved Oxygen Biosensor

The Microbial fuel cells (MFCs) are electrochemical devices that can be utilized as biosensors, specifically Dissolved Oxygen (DO) biosensors. In this research, performance and techno-economic of MFC-based DO biosensors with two sizes, small and large, were evaluated and analysed to determine whether it is more economical to use a small or large reactor. MFC-based DO biosensors were also applied to an irrigation canal. When MFC immersed into distilled water with several variations of DO, the correlation between DO and current density produced equation with R2 values around 0.9989 and 0.9979 for SYMFC and LYMFC, respectively. The power density for SYMFC and LYMFC was 3.48 and 10.89 mW/m2, respectively, in DO 6. Higher power densities are correlated with the electrode surface area, especially the larger cathodic surface area. When applied to the irrigation canal, DO values measured using SYMFC and LYMFC have errors of around 3.39 and 4.42%, respectively, when compared to DO values measured using DO meters. LYMFC requires a capital cost of around $ 234.22 or 2.57 times higher than SYMFC, although it generates almost similar cost per mW/m2, $ 21.51 and $ 26.23 for LYMFC and SYMFC, respectively. The results concluded that yeast MFC -based DO biosensors with smaller sizes can achieve more economical compared to larger sizes.

On the Multiphysics Modeling of Surface Aging Under Cathodic Protection

In order to account and compensate for the dissipative processes contributing to the aging of cathodic surfaces protected by impressed current cathodic protection (ICCP) systems, it is necessary to develop the proper modeling and numerical infrastructure that can predict aging associated with quantities affecting the controller of these systems. In the present work, we describe various approaches for developing cathodic surface aging models (CSAMs) based on both data-driven and first principles-based methodologies. A computational ICCP framework is implemented in a manner that enables the simulation of the effects of cathodic aging in a manner that allows the utilization of various CSAMs that affect the relevant potentiodynamic polarization curves of the cathodic materials. An application of this framework demonstrates the capabilities of this system. We introduce a data-driven CSAM based on a loft-surface approximation, and in response to the limitations of this approach, we also formulate a first principles-based multiphysics and thermodynamic theory for aging. Furthermore, we discuss the design of a systematic experimental task for validating and calibrating this theory in the near future.

Towards an Analytical, Computational and Experimental Framework for Predicting Aging of Cathodic Surfaces

The present work introduces the motivation, architecture and preliminary analytical and computational framework that will eventually lead to aging predictions of cathodic surfaces along with its implications on impressed current cathodic protection (ICCP) systems. This is necessary for adjusting ICCP systems in a manner that reflects the dissipative nature of cathodic surface assemblies while at the same time enabling potential electric far field requirements. We describe various approaches for developing Cathodic Surface Aging Models (CSAMs) based on both data-driven and first principles based methodologies. A computational ICCP framework is implemented to account for cathodic aging in a manner that allows the utilization of various CSAMs. An application of this framework demonstrates the applicability of the implications of the variability of the polarization curves as it is associated with cathodic surface aging. In addition to a data-driven CSAM based on a loft-surface approximation we also introduce a first principles thermodynamic theory for aging and the design of a systematic experimental task for validating and calibrating this theory.

Study on the Cathodic Surface Micro-Profile Effects on the Current Filed Distribution in Processing of Electrochemical Finishing

To improve the ECF leveling effect, according to the actual work of anodic and cathode surface micro-profile, based on the electrodynamics knowledge, established the mathematical model of current field. On the basis of this use of some software to simulate and proceeded numerical calculation, obtained for the influence rule the different cathode surface profile of the current field distribution, and was verified by the experiment. The experimental results show that the variation of the cathode surface micro-profile by changing the current distribution to affect the surface of the anodic and influence of leveling effect by copying the phenomenon will be its own surface profile is copied to the anode. The cathode surface profile is more pointed the affect for the anodic surface will be more obvious.

Fundamental aspects and applications of electrodeposited nanostructured metals

A rational understanding of what occurs during electrocrystallization, defined at a nanolevel, is developed to control electrodeposition processes. The electrokinetic behavior of the elements in solutions and the electrodeposits structure resulting from the electron exchange reaction at the cathodic surface are taken into consideration and compared. Transient electrokinetic parameters are measured with the secondary current pulse (SCP) technique, where a square galvanostatic pulse of a few ms duration is superimposed on the cathode while electrodeposition is running. Two parameters are obtained, the transient Tafel slope and the adsorption pseudo-capacitance; whilst a third parameter, the diffusive time constant, must be introduced if the overvoltage does not arrive to a steady state during the short pulse period. These parameters are related to the growth of different structures and permit a good control of the process. Control of the growth with nanodefinition is key to the development of innovative processes to keep pace with more and more demanding applications and environmental challenges. Examples are given to stress the relevance of the theoretical framework and to show possible implications for electrodeposition technology and its applications.

An Approach for Evaluating the General and Localised Corrosion of Carbon-Steel Containers for Nuclear Waste Disposal

The paper considers the long term corrosion of carbon-steel containers for heat generating nuclear waste in a granitic repository. Under such conditions carbon steel may exhibit general, localised or passive corrosion behaviour depending on the exact composition and redox potential of the groundwater contacting the containers; localised corrosion being of most concern because it has the fastest propagation rate. It is well established, however, that such localised corrosion is only possible when the environment is sufficiently oxidising to maintain a positive potential gradient between the cathodic surface and the corrosion sites, which requires that species with oxidising potentials greater than water need to be present. This fact provides a basis for estimating the periods during which containers may be subject to localised and subsequently to general corrosion, and hence for making an overall assessment of the metal allowance required for a specified container life. A model for the diffusion transport of oxygen has been developed, and a sensitivity analysis has shown that the period of possible localised attack is strongly dependent on the passive film leakage current, the radiation dose rate and the oxygen diffusion coefficient.