Cobalt Waste and Recycling

The increased demand for electronics around the globe - in particular, lithium-ion batteries - has also lead to an increased demand for cobalt (used in said batteries). Many countries have declared cobalt a critical resource due to this increased demand and the potential risks of limited supply. In 2019, it was estimated that 70% of all cobalt came from a single country, the Democratic Republic of Congo, and that slightly under 70% of all cobalt refining was also completed by a single country, China. As such, there is strong interest in obtaining cobalt from secondary sources and the promotion of a circular economy.

While batteries are not the only source of cobalt in waste streams the element is not common in popular alloys or other everyday objects. The Cobalt Institute estimates that 65% of recycled cobalt comes from battery recycling, while a further 24% comes from hard metal alloys. The European Union estimates that, these recycled materials constitute around 35% of their supply of cobalt, with the remaining 65% coming from imports. (Separately from the recycling of cobalt, there is also interest in batteries that do not contain cobalt.)

Sources/Further Reading: (Image source - 2023 article) (2022 article) (Cobalt Institute) (EU Article)

Explosives Chemical Safety

Under OSHA, explosives are defined as "a chemical that causes a sudden, almost instantaneous release of pressure, gas, and heat when subjected to sudden shock, pressure, or high temperature". Because the initiating energy required can vary significantly, each explosive chemical has different safety regulations and handling instructions. Explosive chemicals can fall under two general categories: designed explosives (TNT, fireworks), and chemicals that can become explosive (picric acid, sodium amide; peroxide forming chemicals fall under this category). Generally speaking, these chemicals should be kept away from open flames and ignition sources, and for chemicals that can become explosive the date of first opening should be recorded on container labels.

Sources/Further Reading: (OSHA) (UC Berkeley) (Cornell University) (US DoD)

Image source.

How Are Aluminium Cans Recycled? | How Do They Do It?

SI Derived Units: Power, Radiant Flux, and the Watt

Power and radiant flux use the named SI derived unit of the watt, named for James Watt, first established in 1908 (though it has since been redefined). Power can be defined as the rate at which work is performed, or the amount of energy transferred per unit of time. The watt is equivalent to one joule per second, or in base units kg m^2 s^-3.

Mathematically the watt is represented by the capital letter W; power is often represented by a capital P and radiant flux by the capital Greek letter phi with the subscript of a lowercase e. One of the only other named units of power is the horsepower. Many other unit systems simply use their values for energy over time (ergs per second, BTUs per hour, etc.).

Sources/Further Reading: (Image source - Energy Purse) (Wikipedia: Watt, Power, Radiant flux) (Metric System) (Khan Academy)

A triple point ( 2 ) on a phase diagram is a point at which three phases coexist simultaneously. Triple points exist at a single temperature and pressure.

SI Derived Units: Energy, Work, Heat, and the Joule

The SI derived unit of energy was officially adopted as the joule, after James Prescott Joule, in 1889, only months before Joule's death. It is defined a number of ways, including as "the amount of work done when a force of one newton displaces a mass through a distance of one metre in the direction of that force" and is equivalent to a number of other units. Work and heat are two specific types of energy and therefore also use the joule in SI units.

Mathematically, the joule is represented by a capital J; energy is represented by any number of letters and symbols depending on the usage of the term (energy on its own is often capital E; work capital W, and heat capital Q, but U is often used for internal energy, K for kinetic energy, etc.). The joule is equal to one newton meter, or one watt second, or one coulomb volt, but in base units is one kg m^2 s^-2. Equivalent energy units in other systems are too numerous to give in detail, but include the following: the erg, the kilowatt-hour, the calorie, the British thermal unit or BTU, the electronvolt, and the foot-pound-force.

Sources/Further Reading: (Image source - collegedunia) (Wikipedia: Joule, Energy, Work, Heat) (Metric System) (LibreTexts) (Engineering Toolbox)

Pyrophoric Chemical Safety

Any chemical that catches fire spontaneously when exposed to air (at or below 130F (54.4C)) can be classified as a pyrophoric chemical, though only those that do so in under 5min are classified as such under GHS guidelines. These can include solids, liquids, and gases. Because pyrophoric chemicals are reacting with the oxygen in the air, they are also typically water reactive. As will all general guidelines, specifics can vary from chemical to chemical, however, the following is typically true of handling pyrophoric chemicals. Individuals should wear flame-resistant lab coats/PPE and clothing made from polyester or other synthetic fabrics should be avoided. Pyrophoric chemicals are considered hazardous and should be treated as such during storage, handling (typically in a fume hood or glove box), and disposal. Examples of pyrophoric chemicals include alkali metals (e.g., potassium, sodium), metal powders, metal carbonyls, and many hydrides.

Sources/Further Reading: (Images source - MSDS Authoring Services) (MIT) (Purdue University) (Cornell University) (Stanford University)

SI Derived Units: Pressure, Stress, and the Pascal

The derived unit of pressure - as well as stress and specific variables such as Young's modulus - in SI units is known as the pascal. The unit was named for Blaise Pascal and was officially adopted in 1971. Pressure is often defined as force over area and one pascal is one newton per square meter, or, in base units, kg m^-1 s^-2.

Mathematically the pascal is abbreviated Pa; pressure is often symbolized with either a capital or lowercase p and stress with the lowercase Greek letter sigma. The atmosphere, approximately equivalent to the pressure of the atmosphere at sea level, is sometimes used as a reference point for pressure, but is not a base unit. It is abbreviated atm and 1 atm is approximately 101325 Pa or 101 kPa. US customary units and imperial units use psi, or pounds per square inch, in place of the pascal, with 1 Pa equivalent to approximately 1.45x10^-4 psi. Other units of pressure include the torr, the bar, the barye, mmHg, and inHg.

Sources/Further Reading: (Image source - Pascal Wikipedia) (Pressure Wikipedia) (Stress Wikipedia) (Metric System) (Proportion Air) (MSE Student)

Chemical Compatibility

When storing, using, and disposing of chemicals, it is important to consider their compatibility. Non-compatible chemicals - including chemical compatibility with containers - can lead to spills, fires, or explosions. Compatibility can often be determined based on the chemical pictograms representing hazards - but not always, so appropriate research must be done into all chemicals (and containers), emphasizing the importance of labeling. Some general rules of thumb include separating acids from reactive metals and bases, separating oxidizers from nearly everything else, keeping metal hydrides away from water, and to store solids separate (and above) liquids.

Sources/Further Reading: (Image source - EPFL) (UC San Diego) (Case Western Reserve University) (Brown University) (Rutgers University)

General Chemical Handling

While each chemical presents its own unique hazards, there are some general rules for chemical handling to ensure a safe working environment. Already covered on this blog includes Safety Data Sheets, which contain what hazards a chemical presents, as well as what to do after a chemical spill. Proper labeling of containers also helps reduce hazards. Organization and good housekeeping are key, and communication, engineering controls, and PPE help prevent incidents. Transportation of chemicals should be conducted as safely as possible and secondary containment is often used in the case of a breakage or leak in the primary container.

Sources/Further Reading: (Image source - SFM) (UC San Diego) (OSHA blog) (OSHA) (Smithsonian)

Measuring Luminous Intensity: Goinophotometry

Luminous intensity is primarily measured by goinophotometers, which are designed to measure the light emitted from an object at different angles. There are three general types of goinophotometers, A, B, and C, with the main difference between them being the movement of the axes and their positions relative to the light source being measured. Goinophotometers can also measure luminous flux and aspects of color such as color temperature if equipped with color sensors.

Sources/Further Reading: (Image 1 - Wikipedia) (Image 2 - Pro-lite) (Pro-lite) (Lisun Group blog)

Clinton Joseph Davisson (22 October 1881 – 1 February 1958) and Lester Halbert Germer (10 October 1896 – 3 October 1971)

Both American physicists, Lester Halbert Germer was a junior assistant under Clinton Joseph Davisson when the two of them performed an experiment that led to discovering electron diffraction. Davisson would be awarded the Nobel Prize in physics in 1937 for this discovery, shared with George Paget Thomson, who discovered the same thing independently. Germer, as an assistant, did not share in the Nobel Prize, but his name remains attached to the experiment itself. The Davisson–Germer experiment was conducted on a nickel surface; bombarding it with electrons with known momentum at an angle, a diffraction pattern emerged. It was the first demonstration of the wavelike nature of the electron predicted by de Broglie.

Sources/Further Reading: (Image source - Davisson Wikipedia) (Oxford Reference, Davisson) (IUCr, Davisson) (Davisson Biographical Memoir) (Germer Wikipedia) (Linda Hall Library, Germer)

Luminous Intensity

The seventh and final SI base unit is the unit of luminous intensity, the candela. Luminous intensity is defined as "a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function". It is uniquely dependent on the standard sensitivity of the human eye.

Candles have historically been used to set standards for luminous intensity, leading in 1937 to the creation of a unit known as the new candle defined as "the brightness of the full radiator at the temperature of solidification of platinum is 60 new candles per square centimetre". This was ratified as the candela in 1948, with the exact definition being updated in 1967, 1979, and finally with the SI redefinition of base units in 2019.

The current definition of a candela is "the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 10^12 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian." It is represented mathematically by the lowercase cd.

Sources/Further Reading: (Image source - Luminous Intensity Wikipedia) (Candela Wikipedia) NIST: (Luminous Intensity) (Candela) (Measurement Standards Laboratory of New Zealand)

Amount of a Substance

The sixth SI base unit, out of seven, is the amount of a substance measured in moles [mol]. Mathematically it is usually represented by a lowercase n in chemistry and other fields. Historically the mole was defined in terms of the carbon-12 isotope as the amount of substance in 12g of the element. As of the 2019 redefining of the SI base units, the mole is now defined in terms of the Avogadro constant, whereas one mole "contains exactly 6.02214076×10^23 elementary entities".

There are no significant equivalents to the mole in other unit systems beyond SI and its presence as a base unit has been criticized for a number of reasons. One minor criticism is against the use of the term "amount of substance", with critics arguing for other terms such as enplethy or stoichiometric amount. Others find the need for such a unit irrelevant, arguing that the number of molecules in a substance is a fixed dimensionless quantity and does not need to be represented in terms of moles, among other critiques.

Sources/Further Reading: Amount of a Substance: (Wikipedia) (NIST); Mole: (Wikipedia) (NIST, Image Source)

Hermann Staudinger (23 March 1881 – 8 September 1965)

A German chemist, Hermann Staudinger is known as the man who first understood the molecular structure of high molecular weight polymers, giving birth to the field of polymer chemistry. His published work in 1920 was the first to state that natural polymers such as rubber, starch, and proteins are long chains of short repeating molecular units linked by covalent bonds, focusing particularly on high molecular weight polymers or macromolecules. For this work, he was awarded the Nobel Prize in chemistry in 1953.

Sources/Further Reading: (Image source - ACS) (Science History) (2020 article) (Wikipedia)

Measuring Temperature by Color

There are two primary methods of measuring temperature that rely on the color of an object: pyrometers and liquid crystal thermometers.

The first relies on a principal known as black-body radiation and the incandescence of an object, the same principal that allows people to judge how hot a fire is based on its temperature. All objects give off infrared radiation and pyrometers use said radiation to determine the object's temperature. These thermometers are remote sensing thermometers, meaning that they do not need to be in contact with the object or area of interest to measure the temperature.

Liquid crystal thermometers rely on a different principle known as thermochromism. These thermometers are contact thermometers and, because of the nature of thermochromism, do not hold/record the measured temperature for long and are not digital or electronic. The thermochromism exhibited by some liquid crystals is also used in other applications, including mood rings.

Sources/Further Reading: (Image 1 - Pyrometers Explain That Stuff) (Image 2 - Liquid Crystal Thermometers Smart Glass World) (Elprocus, Pyrometers) (Thermographics, Liquid Crystal Thermometers) (Wikipedia: Pyrometers; Liquid Crystal Thermometers)

Compressed Gas Safety

A number of hazards are present when gas cylinders are in use thanks to the pressure the cylinders are under and depending on the gas in question. Some gases are toxic but even those that aren't can displace air and suffocate individuals. Other gases are flammable, and the cylinders themselves can explode or become a projectile if handled improperly. Compressed gas cylinders come in a variety of standardized sizes, with the larger ones needing to be secured when not being transported. Many organizations also have regulations on transporting cylinders in elevators, though specifics vary. In addition, cylinders should be stored away from sparks, flames, or other reactions that might include high temperatures.

Sources/Further Reading: (Image source - Safety by Design) (Brown University) (OSHA) (Airgas) (UC Berkeley)