Significance of Molten Hydroxides With or Without Molten Carbonates in High-Temperature Electrochemical Devices

Due to their low melting point and high conductivity molten hydroxides are interesting electrolytes, or additive to other molten electrolytes for high-temperature electrochemical devices. There is nowadays a revival of such reactive media, first of all for their significant role in the electrode mechanisms in molten carbonate fuel cells (MCFCs) and the reverse co-electrolysis of water and carbon dioxide process, but also in different applications, among which direct carbon fuel cells (DCFCs), hybrid carbonate/oxide fuel cells. This overview shows the properties and interest of molten hydroxides and their use in relevant energy devices, pointing out their direct use as electrolytic media or as key species in complex kinetic processes. A thorough understanding of their behavior should allow improving and optimizing significantly fuel cells, electrolyzers, and probably also CO2 capture and valorization.

Formation of plutonium (IV) silicate species in very alkaline reactive media

Studying the speciation of Pu(IV) in very alkaline and silicate ions rich reactive media allowed identifying the formation of plutonium (IV)-silicate colloidal suspensions which were stable for months. These colloids...

A Numerical Study of Crown Forest Fires Behaviour

The theoretical investigation of the problems oflarge forest fires initiation and spread was carried out in thispaper. Mathematical model of forest fire was based on ananalysis of experimental data and using concept and methodsfrom reactive media mechanics. The research was based onnumerical solution of three dimensional Reynolds equations. Theboundary-value problem is solved numerically using the methodof splitting according to physical processes. A discrete analoguefor the system of equations was obtained by means of the controlvolume method. The developed numerical model of forest fireinitiation and spreading would make it possible to obtain adetailed picture of the variation in the velocity, temperature andchemical species concentration fields with time. The results ofcalculation give an opportunity to describe conditions of crownforest fires initiation and spread at different properties of forestsand meteorological conditions. Forest fires contours and theirsizes depend on crown properties: bulk density, moisture contentof forest fuel, distribution of combustion sources and etc.

Impact of hydraulic retention time on phosphorus removal from wastewater using reactive media

Phosphorus (P) discharge from wastewater treatment plants into the environment contributes to eutrophication issues. Reactive media filters represent an effective, simple and cost-effective solution to decrease the P content. Previous research used various experimental designs and often synthetic wastewater, making assessment of real-world performance difficult. This study assesses the impact of the hydraulic retention time (HRT) on P removal using real wastewater to refine design criteria for full-scale installations. Four media were compared in column experiments for >200 days. Different HRTs were applied and initially the media achieved low P effluent concentrations of >0.1 mg/L PO4–P, increasing over time. Best P removal was observed for the highest HRT with on average >99%. HRT was seen to be the driving factor for P removal rather than media capacity. Three of the four materials showed pH levels above 12 initially, decreasing over time. Water quality parameters, including organics, solids and metals, were monitored. In-depth analysis confirmed formation of calcium phosphate precipitation on the media's surface. The results suggest the importance of an optimal HRT to achieve high P removal and show that the reactive media application is an appropriate technology for P removal on small sites if the elevated pH is addressed.