Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference and identifiable chemical change. These reactions involve electrons moving via an electronically-conducting phase between electrodes separated by an ionically conducting and electronically insulating electrolyte.
An electrochemical cell is a device that generates electrical energy from chemical reactions. Electrical energy can also be applied to these cells to cause chemical reactions to occur. Electrochemical cells that generate an electric current are called voltaic or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells.
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity."
An electrolyte is a medium containing ions that are electrically conductive through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dissolving, the substance separates into cations and anions, which disperse uniformly throughout the solvent. Solid-state electrolytes also exist. In medicine and sometimes in chemistry, the term electrolyte refers to the substance that is dissolved.
The lead-acid battery is a type of rechargeable battery first invented in 1859 by French physicist Gaston Planté. It is the first type of rechargeable battery ever created. Compared to modern rechargeable batteries, lead-acid batteries have relatively low energy density. Despite this, they are able to supply high surge currents. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by starter motors. Lead-acid batteries suffer from relatively short cycle lifespan and overall lifespan, as well as long charging times.
An electrolytic cell is an electrochemical cell that utilizes an external source of electrical energy to force a chemical reaction that would otherwise not occur. The external energy source is a voltage applied between the cell's two electrodes; an anode and a cathode, which are immersed in an electrolyte solution. This is in contrast to a galvanic cell, which itself is a source of electrical energy and the foundation of a battery. The net reaction taking place in a galvanic cell is a spontaneous reaction, i.e., the Gibbs free energy remains -ve, while the net reaction taking place in an electrolytic cell is the reverse of this spontaneous reaction, i.e., the Gibbs free energy is +ve.
The chloralkali process is an industrial process for the electrolysis of sodium chloride (NaCl) solutions. It is the technology used to produce chlorine and sodium hydroxide, which are commodity chemicals required by industry. Thirty five million tons of chlorine were prepared by this process in 1987. The chlorine and sodium hydroxide produced in this process are widely used in the chemical industry.
A regenerative fuel cell or reverse fuel cell (RFC) is a fuel cell run in reverse mode, which consumes electricity and chemical B to produce chemical A. By definition, the process of any fuel cell could be reversed. However, a given device is usually optimized for operating in one mode and may not be built in such a way that it can be operated backwards. Standard fuel cells operated backwards generally do not make very efficient systems unless they are purpose-built to do so as with high-pressure electrolysers, regenerative fuel cells, solid-oxide electrolyser cells and unitized regenerative fuel cells.
Electrocoagulation (EC) is a technique used for wastewater treatment, wash water treatment, industrially processed water, and medical treatment. Electrocoagulation has become a rapidly growing area of wastewater treatment due to its ability to remove contaminants that are generally more difficult to remove by filtration or chemical treatment systems, such as emulsified oil, total petroleum hydrocarbons, refractory organics, suspended solids, and heavy metals. There are many brands of electrocoagulation devices available, and they can range in complexity from a simple anode and cathode to much more complex devices with control over electrode potentials, passivation, anode consumption, cell REDOX potentials as well as the introduction of ultrasonic sound, ultraviolet light and a range of gases and reactants to achieve so-called Advanced Oxidation Processes for refractory or recalcitrant organic substances.
Electrolysis of water is using electricity to split water into oxygen and hydrogen gas by electrolysis. Hydrogen gas released in this way can be used as hydrogen fuel, but must be kept apart from the oxygen as the mixture would be extremely explosive. Separately pressurised into convenient 'tanks' or 'gas bottles', hydrogen can be used for oxyhydrogen welding and other applications, as the hydrogen / oxygen flame can reach approximately 2,800°C.
Electrochemistry, a branch of chemistry, went through several changes during its evolution from early principles related to magnets in the early 16th and 17th centuries, to complex theories involving conductivity, electric charge and mathematical methods. The term electrochemistry was used to describe electrical phenomena in the late 19th and 20th centuries. In recent decades, electrochemistry has become an area of current research, including research in batteries and fuel cells, preventing corrosion of metals, the use of electrochemical cells to remove refractory organics and similar contaminants in wastewater electrocoagulation and improving techniques in refining chemicals with electrolysis and electrophoresis.
In electrochemistry, Faraday efficiency describes the efficiency with which charge (electrons) is transferred in a system facilitating an electrochemical reaction. The word "Faraday" in this term has two interrelated aspects: first, the historic unit for charge is the faraday (F), but has since been replaced by the coulomb (C); and secondly, the related Faraday's constant correlates charge with moles of matter and electrons. This phenomenon was originally understood through Michael Faraday's work and expressed in his laws of electrolysis.
Gas diffusion electrodes (GDE) are electrodes with a conjunction of a solid, liquid and gaseous interface, and an electrical conducting catalyst supporting an electrochemical reaction between the liquid and the gaseous phase.
A solid oxide electrolyzer cell (SOEC) is a solid oxide fuel cell that runs in regenerative mode to achieve the electrolysis of water by using a solid oxide, or ceramic, electrolyte to produce hydrogen gas and oxygen. The production of pure hydrogen is compelling because it is a clean fuel that can be stored, making it a potential alternative to batteries, methane, and other energy sources. Electrolysis is currently the most promising method of hydrogen production from water due to high efficiency of conversion and relatively low required energy input when compared to thermochemical and photocatalytic methods.
Conductivity or specific conductance of an electrolyte solution is a measure of its ability to conduct electricity. The SI unit of conductivity is siemens per meter (S/m).
Electrokinetic remediation, also termed electrokinetics, is a technique of using direct electric current to remove organic, inorganic and heavy metal particles from the soil by electric potential. The use of this technique provides an approach with minimum disturbance to the surface while treating subsurface contaminants.
Electrodeionization (EDI) is a water treatment technology that utilizes DC power, ion exchange membranes, and ion exchange resin to deionize water. EDI is typically employed as a polishing treatment following reverse osmosis (RO), and is used in the production of ultrapure water. It differs from other RO polishing methods, like chemically regenerated mixed beds, by operating continuously without chemical regeneration.
A mixed oxidant solution (MOS) is a type of disinfectant that has many uses including disinfecting, sterilizing, and eliminating pathogenic microorganisms in water. An MOS may have advantages such as a higher disinfecting power, stable residual chlorine in water, elimination of biofilm, and safety. The main components of an MOS are chlorine and its derivatives, which are produced by electrolysis of sodium chloride. It may also contain high amounts of hydroxy radicals, chlorine dioxide, dissolved ozone, hydrogen peroxide and oxygen from which the name "mixed oxidant" is derived.
Pulse electrolysis is an alternate electrolysis method that utilises a pulsed direct current to initiate non-spontaneous chemical reactions. Also known as pulsed direct current (PDC) electrolysis, the increased number of variables that it introduces to the electrolysis method can change the application of the current to the electrodes and the resulting outcome. This varies from direct current (DC) electrolysis, which only allows the variation of one value, the voltage applied. By utilising conventional pulse width modulation (PMW), multiple dependent variables can be altered, including the type of waveform, typically a rectangular pulse wave, the duty cycle, and the frequency. Currently, there has been a focus on theoretical and experimental research into PDC electrolysis in terms of the electrolysis of water to produce hydrogen. Past research has demonstrated that there is a possibility it can result in a higher electrical efficiency in comparison to DC electrolysis. This would allow electrolysis procedures to produce greater volumes of hydrogen with a reduced electrical energy consumption. Although theoretical research has made large promise for the efficiencies and benefits of utilising pulse electrolysis, it has many contradictions including a common issue that it is difficult to replicate the successes of patents experimentally and produces its own negative effects on the electrolyser.
Electrolytic iron is a form of high purity iron, obtained by electrolysis. It has a high purity greater than 99.95% with trace elements accounting for only a millionth of a decimal.
