Effect of Organic Inhibitor on Corrosion of Mild Steel in Hydrochloric Acid

The inhibition effect of thiourea, hexamethylenetecramine and N-N I -dicyclohexylthiourea on mild steel corrosion in hydrochloric acid solutions has been examined by means of a hydrogen-evolution measurement and the surface observation of corroded specimens. The evoiltion -rate of hydrogen by the steel was kept constant in the acid solution with thiourea. In contrast, the evo- 1ution-rate redueced with time in the acid solution with the other inhibitors. The inhibitor concentration at which the inhibitor efficiency was over 90% was 500ppm for thiourea and only 50ppm for the other inhibitors. The surface of corroded specimens was much smoother in the acid solution with hexamethylenetetramine than in the acid solution with thiourea, regardless of the corrosion-rate. Thus, hexamethylenetetramine has been found as an excellent inhibitor for the corrosion of mild steel in hydrochloric acid solution

Study on the Floatability of Mineral Particles in the Presence of Surface Active Agents I : Relation between Adsorption of the Collector Ion and the Electrokinetic Potential in Flotation

The electro-osmotic velocity, the adsorption density and the floatability of mineral particles were measured for the following systems : fluorite-sodium dodecyl benzene sulphonate, quartz-sodium dodecyl benzene sulphonate, quartz-octadecyl dimethyl benzyl ammonium chloride, scheelite-octadecyl dimethyl benzyl ammonium chloride and quartz-dodecyl ammonium acetate. The relations among the differences in the zeta-potential, the adsorption density and the floatability are discussed. As a result of this research, it was found that the difference in the zeta-potential of the mineral can be correlated with the adsorption density of the collector on the mineral surface, and that, therefore, the floatability of the mineral can be correlated with the difference in the zeta-potential

Complexation of F⁻ by Li⁺ and Mg²⁺ Ions as Inorganic Anion Acceptors in Lactone-Based Li⁺/F⁻ and Mg²⁺/F⁻ Hybrid Electrolytes for Fluoride Shuttle Batteries

The development of high-quality fluoride-ion transporting electrolytes is a crucial demand for fluoride shuttle batteries (FSBs). However, the uncontrolled chemical and electrochemical activities of fluoride ions narrow the available potential window, hindering the development of high-voltage FSB cells. We present a method for upgrading recently developed lactone-based liquid fluoride electrolytes by complexation of F⁻ with Li⁺ and Mg²⁺ ions. In the resultant Li⁺/F⁻ and Mg²⁺/F⁻ hybrid electrolytes, Li2F+ and MgF+ were the most probable soluble complexes, and the effective fluoride concentrations could reach ∼0.15 M along with excess Li⁺(Mg²⁺) ions. Unique interactions between F⁻ and Li⁺(Mg²⁺) were observed using ¹⁹F nuclear magnetic resonance spectroscopy. Li⁺(Mg²⁺) ions thus served as inorganic anion acceptors with ultimate redox stabilities to expand the negative potential window of the electrolytes to near −3 V vs SHE. The proposed complex formation was also supported by a conductometric titration method. We demonstrated the superior and versatile electrochemical performances of the Li⁺/F⁻ hybrid electrolyte, which enabled reversible charge/discharge reactions of various metal electrodes and composite electrodes in a wide range of redox series. Further, the Li⁺/F⁻ hybrid electrolyte opened valid new reaction paths for aluminum, making it a promising negative electrode in high-voltage FSB cells

Lactone-Based Liquid Electrolytes for Fluoride Shuttle Batteries

Rechargeable secondary batteries operating through fluoride-ion shuttling between the positive and negative electrodes, referred to as fluoride shuttle batteries (FSBs), offer a potentially promising solution to overcoming the energy-density limitations of current lithium-ion battery systems. However, there are many technical issues that need to be resolved to achieve high-quality fluoride-carrying electrolytes and ensure reversible transformations between a metal and its fluoride counterpart at both electrodes. Here, we introduce novel lactone-based liquid electrolytes consisting either of CsF or KF, which are prepared by a solvent substitution method. Although the maximum fluoride-ion concentration achieved by the method is approximately 0.05 M, these systems behave as strong electrolytes where CsF(KF) is almost fully dissociated into Cs⁺(K⁺) and F⁻ ions to give a maximum ionic conductivity of 0.8 mS.cm⁻¹. Hence, the solvent supports electrochemically active fluoride ions that can drive reversible metal/metal-fluoride transformations at room temperature for a wide range of metal electrodes. However, irreversible reductive reactions of the solvent, also promoted by the fluoride ions, limit currently the negative potential window to approximately −1.5 V vs the standard hydrogen electrode