MATERIAL REVIEW ON: TABLE SALT (NaCl)
DATE/UPDATED: DEC. 18, 2022
ELMA O. CAMION-FIEL
GEN. SCI. 213
INTRODUCTION
Rock salt (NaCl) is an ionic compound that occurs naturally as white crystals.
(Michael Ford, 2021). Not just tasty but essential for life, salt has a long and
tumultuous history all its own, BUTLER (2018).
The fact is that throughout history, salt—called sodium chloride by
chemists—has been such an important element of life that it has been the subject
of many stories, fables, folktales and fairy tales. It served as money at various times
and places, and it has been the cause of bitter warfare.
Salt is the common name for the substance sodium chloride (NaCI), which
occurs in the form of transparent cubic crystals. Although salt is most familiar as a
food supplement, less than 5% of the salt produced in the United States is used for
that purpose. About 70% is used in the chemical industry, mostly as a source of
chlorine.
Salt doesn’t just make your food tastier—it’s actually required for life. Sodium
chloride, also known as common salt or table salt, is a chemical compound with
the formula NaCl. Its mineral form is called halite. It is highly soluble in water and
is the salt most responsible for the salinity of the ocean and of the extracellular fluid
of many multicellular organisms.
Sodium ions help the body perform a number of basic tasks, including
maintaining the fluid in blood cells and helping the small intestine absorb nutrients.
We can’t make salt in our own bodies, so humans have always had to look to their
environments to fill the need. Early hunters could get a steady supply of salt from
meat, but agricultural groups had to seek it out by following animal tracks to salt
deposits.
HISTORY OF THE MATERIAL
In the Stone Age, people didn’t need to find salt, because they were hunting a lot of
their food, and eating a lot of red meat. Red meat has plenty of salt in it, naturally, without
having to go find any extra salt Karen Carr (2017).
But when people began to farm, about 10,000 BC, they started to eat mainly grains
like rice and wheat and barley and millet, and very little meat. Then they really needed
another way to get salt. And when people began to keep cows and sheep, they needed to
feed the animals salt too. People also used salt to preserve all different kinds of food,
because there were no refrigerators -you use salt to make bacon, or ham, or salted fish,
or pickles Karen Carr (2017).
The earliest evidence we have for people producing salt comes from northern China,
where people seem to have been harvesting salt from a salt lake, Lake Yuncheng, by 6000
BC and maybe earlier Karen Carr (2017).
By about 4500 BC, Central Asian people along the shores of the Caspian Sea (in
modern Azerbaijan) were mining rock salt underground. This is the earliest known salt
mine in the world. Probably these people were selling the salt along early Silk Road trade
routes, perhaps in exchange for copper or obsidian, wheat from West Asia and milletfrom
China, Karen Carr (2017).
In Egypt, people were using salt to preserve meat and fish by about 3000 BC, around
the beginning of the Old Kingdom. The Egyptians also used salt to preserve mummies.
They evaporated seawater from the Mediterranean Sea, and also bought salt from Libya,
Sfax in Tunisia, and Nubia to their south.
By 800 BC, Chinese written records tell us that people in China were producing salt
by filling clay jars with ocean salt water and boiling it until the water boiled away and only
the salt was left. After the Chinese learned how to make iron from West Asia, about 700
or 600 BC during the Eastern Chou dynasty, they started using iron pans instead of clay
ones to boil water for salt; this saved a lot of fuel. They were definitely using iron pans by
450 BC. The Etruscans in Italy, and the early Romans, and the Carthaginians in North
Africa, also used evaporation to produce salt.
About the same time (700 BC), in Europe, the Indo-European Celts were mining salt
underground in modern Austria, Hungary, southern Germany and Poland. The Celts sold
their salt to other people – the Greeks, the Etruscans, and the Carthaginians, maybe the
Phoenicians. The Celts also sold salted meat – salami, ham, and bacon. In exchange, the
Celts bought glass and pottery for their houses and their graves.
INDUSTRIAL APPLICATION OF THE MATERIAL
CLEANING AND SAFETY
As far as chemicals go, salt is about as versatile as it gets. Here are a few of the ways salt
is used to promote cleaning and safety across industries:
A. Detergents: Soaps, detergents, and solvents contain salt as a filler. When several
chemicals are present, salt separates the chemicals so they can perform their
specific tasks.
B. Chlorine production: Sodium chloride’s main industrial use is in the production of
chlorine, a feedstock for plastics and other chemicals.
C. Pool maintenance: Pools and spas are more frequently being outfitted with saltwater
systems, which gives the same water sanitation as chlorine while reducing chlorine
levels.
D. Water treatment: Salt flocculates calcium and magnesium, which softens water.
E. Road maintenance: Industrial salt is an inexpensive method for controlling ice or
melting ice on roads since it lowers water’s freezing point. As roads are maintained
or constructed, salt added to soil binds it more tightly for a firmer surface.
F. Food and beverage: In processed meats, salt enriches color, controls bacterial
growth, binds sausage, and softens meat. For breads and dairy products, salt
coordinates fermentation rates and enhances flavor. Flour contains salt to
strengthen gluten and heighten flavor.
MANUFACTURING
A. Metallurgy: Metal processing creates abundant impurities. Salt removes the
impurities during refining or smelting of aluminum, beryllium, copper, steel,
vanadium, and uranium.
B. Rubber synthesizing: In combination with sulfuric acid and water, industrial salt
coagulates latex, thereby separating rubber from latex, to create neoprene and white
rubber.
C. Tanning: Salt reduces moisture and bacteria in the leather working process.
1. Use of Industrial Salt for De-Icing
One of the most prevalent salt use cases is de-icing. When using de-icing rock salt, the
application can help maintain roads, sidewalks, and other surfaces that can be potentially
dangerous when a layer of ice is developed. This de-icing road salt is spread across the
roads to create a layer of brine before the surface is able to freeze, helping to prevent or
delay ice formation.
In the case that the roadways or sidewalks are already covered with a layer of snow, the
salt can be used to lower the water’s freezing point, helping to melt the snow and delay
the ice formation. Industrial salt is an invaluable tool to keep roads safe and prevent
accidents.
2. Salt Applications in the Oil Industry
The use of salt is also common in the oil industry. In many cases, it is used in an
oil drilling rig to make it safer and more efficient. It can also be used as an additive in mud
when used as a drilling fluid.
Here is an explanation of how industrial salt is used in the oil industry:
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It increases the density of the soil and makes the drilling process safer;
When used in mud as a drilling fluid, it acts as a lubricant and coolant for the
drilling head;
Salt applications can be used as diverting agents, flocculants, stabilizers, acidizing
specialty additives, and thinners/dispersants.
3. Industrial Salt in the Energy Industry
Another example of what is salt used for
applies to the energy industry. When producing
energy such as solar power, the process itself
requires industrial salt. This helps to maintain a
certain level of salinity that’s required for specific
reactions to take place.
4. Uses of Salt in the Chemical Industry
Industrial salt is also widely used in the chemical industry to produce different
chemicals. It can be used as a raw material when manufacturing chemicals such as
chlorine, soda ash, and caustic soda. In addition, industrial salt can be used to
manufacture products such as sodium nitrate, sodium bicarbonate, liquid sodium,
metallic sodium, sodium sulfate, and more.
5. Industrial Salt for Electrolysis
Industrial salt can be used to create chlorine, know that it is a primary component
of disinfection and hygiene products. Chlorine production stems from the electrolysis of a
saturated salt solution, making sodium chloride the raw material when producing
chlorine. For example, Turkey’s largest salt producer Koyuncu Salt offers industrial salt
for many industrial uses such as in the chlor alkali industry.
6. Salt Uses in the Metal Industry
The use of salt in the metal industry is also common.
In many cases, industrial salt is used while processing
metals and secondary aluminum making to remove the
impurities.
7. Salt for the Textile Industry
In the textile industry, it’s common for industrial salt
to be used for textiles to fix batches of dye. This allows the textile industry to achieve
standardized dye.
8. Salt in the Pharmaceutical Industry
Another use of salt is in the pharmaceutical industry. Salt is an ingredient that is
commonly used to prepare saline solutions as well as in the production of capsules.
Industrial salt is used to make intravenous formulas, contact solutions, and many more
products in the pharma industry.
9. Salt in the Soap Industry
Sodium chloride in soap is also common as industrial salt is commonly used as an
additive filler in solvents and detergents. Salt is often added as a filler to easily separate
the chemicals.
10. Salt for Water Treatment
Water treatment refers to removing contaminants and undesirable components. It
also reduces the water’s concentration for industrial water supply and plays an important
role in providing humans with clean water for drinking and bathing. Water softening salt
can be used for both domestic and industrial purposes including regeneration salt and
dishwasher salt.
11. Salt for the Food Industry
Salt in the food industry helps to cure
and preserve meat and fish for thousands of
years. It is a simple yet impactful way to
preserve food for humans around the world.
As soon as salt is applied to meat or fish, it
draws out the moisture to prevent bacteria
growth, preserving it for weeks at a time.
Many microorganisms cannot live in
an overly salty environment: water is drawn
out of their cells by osmosis. For this reason,
salt is used to preserve some foods, such as smoked bacon or fish, and can also be used
to detach leeches that have attached themselves to feed.
In processed meats, salt enriches color, controls bacterial growth, binds sausage, and
softens meat. For breads and dairy products, salt coordinates fermentation rates and
enhances flavor. Flour contains salt to strengthen gluten and heighten flavor.
12. Salt in Agriculture
Another industrial use for salt is in agriculture. For example, silage is a forage
preservation technique that requires spontaneous lactic acid fermentation under
anaerobic conditions. In many countries, silages are used as animal feed, and salt
preserves forage and are used to increase the rate of acidification and extend the shelf life.
It limits bacterial growth and preserves its nutritional properties.
13. Salt as a Dust Control Solution
Did you know that salt can also be used to control dust on unpaved roads? Most
commonly used is Calcium Chloride; it works to absorb the moisture in the air and
minimizes the production and spread of dust. Calcium chloride has a higher concentration
and it remains in liquid form even on particularly hot and dry days. Magnesium
chloride can also be used to control dust by removing moisture from the air to reduce the
movement of dust particles. It acts as a road stabilizer and allows the dust to stick to the
road.
RECENT APPLICATION OF THE MATERIAL
This material is used daily especially in Food Industry.
CURRENT RESEARCHES ON THE MATERIAL (2018-PRESENT)
1. Effect of Sodium Chloride Concentration on Saturated Permeability of
Remolded Loess (2020)
Loess contains many sodium and chloride ions that can easily be leached
when seepage occurs, thus affecting the mechanical properties of loess. This study
investigated a series of sodium chloride solution concentrations to explore their
influence on the permeability of remolded loess, as well as the underlying
mechanism of such. The results indicated that the saturated hydraulic conductivity
of remolded loess increases with time in response to different sodium chloride
concentrations, and the sample was more permeable with increasing concentration.
Moreover, the salt effect promoted the dissolution of calcite and dolomite, and the
cation exchange stimulated the leaching of other cations, thus leading to further
structural loosening. Furthermore, the aggregation of clay particles increased, thus
forming a larger pore space among aggregates and providing effective channels for
permeation. These findings provide a theoretical basis for an improved
understanding of channel degradation in the loess area of Northwest China.
2. The role of sodium chloride in the sensory and physico-chemical properties of
sweet biscuits (2020)
Salt is included in many foods which consumers do not regard as salty. This
“hidden-salt” may offer functional benefits but is often overlooked in sodium
reduction strategies. This study investigated its role in shortbread-like sweet
biscuits (1.05 g NaCl/100 g). Sensory tests revealed significant flavour and texture
differences after a salt reduction of 33% (0.86 g/ 100 g). This was explained by
differences in the partitioning of hydrophobic aroma compounds into the headspace
and a significant impact on structure. Texture analysis and X-ray-µCT
measurements revealed a reduced hardness with larger and more air cells in saltreduced biscuits. It is suggested that salt impacts on cereal proteins by altering
their aggregation around flour particles and at bubble walls and that slower water
loss occurs in salted matrices during baking. Hence, this study revealed the key
properties significantly affected by salt reduction and proposes an explanation
which will help to develop a targeted “hidden-salt” reduction strategy.
3. Effect of NaCl road salt on the ionic composition of soils and Aesculus
hippocastanum L. foliage and leaf damage intensity (2021)
We investigated the accumulation of sodium chloride in roadside soils and
common horse chestnut Aesculus hippocastanum L. under urban conditions to
evaluate changes in soil and leaf ionic content and their relationship with foliar
damage, considering the visual assessment of trees of the same health status. A
total of 15 field sites were assessed in late June 2016. The analysis included soil
granulometric composition, pH, electrical conductivity, and the content of Cl− , Na+
, K+ , Ca2+, and Mg2+ ions in soil and foliage samples. The results showed increased
salinity and alkalization of roadside soils together with the decreased magnesium
content. Foliage samples manifested significantly higher concentrations of Na+ and
Cl− . A wide range of Cl− content was noted in leaves (2.0–11.8% d.w.) regardless of
their damage index. On the contrary, leaf damage was strongly correlated with
increasing Na+ concentrations and decreasing K+ and Mg2+. A severe imbalance of
nutrients, and therefore poor urban tree vitality, can be attributed to the excessive
accumulation of de-icing salt. However, further research would be needed to clarify
the discrepancy between the extent of leaf damage and chloride content.
4. Effects of NaCl Concentrations on Growth Patterns, Phenotypes Associated
With Virulence, and Energy Metabolism in Escherichia coli BW25113 (2021)
They investigated how NaCl concentrations influenced growth patterns,
biofilm formation, oxidative stress resistance, and motile ability. In terms of
energy metabolism that is central to bacterial survival, glucose consumption,
glycogen accumulation, and trehalose content were measured in order to
understand their roles in dealing with the fluctuation of osmolarity. According
to the results, trehalose is preferred than glycogen at high NaCl concentration.
In order to dissect the molecular mechanisms of NaCl effects on trehalose
metabolism, we further checked how the impairment of trehalose synthesis
pathway (otsBA operon) via singlegene mutants influenced E. coli durability
and virulence under salt stress. After that, we compared the transcriptomes
of E. coli cultured at different NaCl concentrations, through which
differentially expressed genes (DEGs) and differential pathways with
statistical significance were identified, which provided molecular insights into
E. coli responses to NaCl concentrations. In sum, this study explored the in
vitro effects of NaCl concentrations on E. coli from a variety of aspects and
aimed to facilitate our understanding of bacterial physiological changes under
salt stress, which might help clarify the linkages between bacterial durability
and virulence outside hosts under environmental stresses.
- Li F, Xiong X-S, Yang Y-Y, Wang J-J, Wang M-M, Tang J-W, Liu Q-H, Wang L
and Gu B (2021) Effects of NaCl Concentrations on Growth Patterns,
Phenotypes Associated With Virulence, and Energy Metabolism in Escherichia
coli BW25113
SIGNIFICANCE OF THE MATERIAL ON THESIS/DISSERTATION PREPARATION
I choose SALT(NaCl) for my material review mainly because:
1. I am planning to study on water quality in our community because of
scarcity of drinking water resources in our place despite the fact that it is
located in mountain area where is abundant supply of water.
2. Salinity is one of the of the parameters to be checked when checking water
quality and salt is the reason for salinity.
3. This material will greatly give benefits is used widely in every aspect of our
daily life.
STRUCTURE OF THE MATERIAL
The structure of NaCl is formed by repeating the face centered cubic unit cell. It has
1:1 stoichiometry ratio of Na:Cl with a molar mass of 58.4 g/mol. Compounds with the
sodium chloride structure include alkali halides and metal oxides and transition-metal
compounds, Osborne, et al (2022).
The crystal structure of sodium chloride, NaCl, a typical ionic compound. The
smaller purple spheres represent sodium cations, Na+, and the larger green spheres
represent chloride anions, Cl−Cl−.
The unit cell of NaCl consists of Na+ ions and Cl− ions. There are four types of site:
unique central position, face site, edge sites and corner site, which are used to determine
the number of Na+ ions and Cl- ions in the unit cell of NaCl. When counting the number
of ions, a corner site would be shared by 7 other unit cells. Therefore, 1 corner would be
1/8 of an ion. A similar occurrence happens with the face site and the edge sites. For a
face site, it is shared by 1 other unit cell and for an edge site, the ion is shared by 3 other
unit cells. NaCl is a face centered cubic unit cell which has four cations and four anions.
This can be shown by counting the number of ions and multiplying them in relation to
their position
PROPERTIES OF THE MATERIAL
PROCESSES INVOLVED IN THE MANUFACTURE OF THE MATERIAL
Processing rock salt
Underground salt deposits are usually discovered by prospectors
searching for water or oil. When salt is detected, a diamond-tipped,
hollow drill is used to take several regularly spaced core samples
throughout the area.
When a site is selected for mining, shafts are sunk into the center of
the salt deposit. Then a machine that looks like a gigantic chain saw is
used to cut a slot about 6.0 inches (15 cm) high, about 66 feet (20 m)
wide, and about 10 feet (3 m) deep into the salt at floor level.
Chunks of blasted rock salt are transported to an underground
crushing area. Here they are passed over a grating known as a grizzly
which collects pieces smaller than about 9 inches (23 cm).
Processing brine
The simplest method of evaporating brine is solar evaporation, but it can only be
used in hot, dry, sunny places. The brine is collected into shallow ponds and allowed to
evaporate in the sun. The brine is collected into shallow ponds and allowed to evaporate
in the sun.
The salt is scooped up by machines running on temporary railroad tracks laid on
top of the layer of salt. It is then washed with highly concentrated salt water.
Most brine is processed by a multiple-effect vacuum evaporator. This device consists
of three or more closed metal cylinders with conical bottoms.
Brine may also be processed in a grainer. The brine is chemically purified and
pumped into a long open pan heated by steam running through pipes immersed in the
brine. The brine is heated to a temperature slightly below the boiling point and flakes of
salt form on its surface as it evaporates.
At this point salt used for most purposes is ready to be packaged in bags or boxes
and shipped to consumers. To make iodized table salt, however, potassium iodide is
added, then magnesium carbonate, calcium silicate, calcium phosphate, magnesium
silicate, or calcium carbonate is added to make it free-flowing. The salt is then packaged
and shipped to restaurants and grocery stores.
Deep-Shaft Mining: Like mining for any other mineral, salt exists as deposits in
underground ancient sea beds, typically miles long and thousands of feet deep. Most
“rock salt” (used to de-ice highways and walkways) is produced this way.
Solution Mining: Wells, similar to oil and gas wells, are set up over salt deposits,
and fresh water is injected to dissolve the salt. The brine is then pumped out and
taken to a plant for evaporation.
Solar Evaporation: The oldest salt production method in warmer climates, salt is
first captured in shallow ponds, where the wind and sun evaporate the water. The
salt is then harvested either by hand or by machine.
Quality Control
Specifications for salt vary widely according to the intended use. Salt
intended for human consumption must be much purer than salt used
for melting snow and ice, but salt used for certain scientific purposes
may need to be even purer.
For most purposes, rock salt is allowed to have a gray, pink, or brown
tinge rather than being pure white. The impurities that cause these
colors may make up as much as 4% of a test sample. To test solubility,
a 0.7-ounce (20 g) sample is placed in 6.8 fluid ounces (200 ml) of water.
It should completely dissolve in no more than 20 minutes.
REFERENCE (PROGRESSIVE)
1. The Industrial Applications of Salt — Bell Chem (2022)
2. Wood, F. Osborne , Ralston, . Robert H. and Hills, . John M. (2022, November 16).
salt. Encyclopedia Britannica. https://www.britannica.com/science/salt
3. Carr, K.E. Where does salt come from?. Quatr.us Study Guides, June 23, 2017.
Web. November 20, 2022.
4. Sheila Mesulam. Salt: Everything you wanted to know about this ancient, essential
mineral, 1/30/2008
5. How salt is made - material, used, processing, procedure, industry, machine, Raw
Materials (madehow.com)
6. History of Salt | SaltWorks® (seasalt.com)