Sodium Hydroxide Hazards/NaOH (with 18 applications and synthesis): Amazing Overview

Sodium hydroxide, often known as caustic soda, is a widely used chemical component having several uses in a variety of industries and daily life. It has the chemical formula NaOH and is an inorganic base. One of the most used industrial chemicals, sodium hydroxide is noted for its potent alkaline characteristics. The chloralkali method, which entails the sodium chloride solution electrolysis, is the main techniques to generate it industrially. As a byproduct of this process, sodium hydroxide, chlorine gas, and hydrogen gas are created.

Typically, sodium hydroxide is found as hygroscopic, white, odorless flakes, pellets, or beads. It dissolves easily in water and produces a caustic, corrosive, and extremely alkaline solution. sodium hydroxide hazards may include severe chemical burns and can be dangerous if handled improperly.

Detailed applications:

Besides the sodium hydroxide hazards, it is a desirable and necessary chemical for various applications due to its strong alkaline characteristics and capacity to react with other substances.

  1. Tissue Digestion: Sodium hydroxide is used in histology and pathology labs to digest tissues and extract cells from the extracellular matrix. This procedure is crucial for understanding cell architecture and locating certain disorders.
  2. Cell lysis: Sodium hydroxide is used to split open cells and extract their contents for a variety of biological experiments, such as the extraction of DNA and proteins.
  3. Food Processing: Among other things, sodium hydroxide is used in food processing to peel fruits and vegetables, cure olives, and change the texture of some foods. Due to its high reactivity, it is handled with caution.
  4. Chemical Industry: Sodium hydroxide is widely utilized to create a variety of chemical compounds in the chemical industry. It is employed in the creation of organic compounds, detergents, soaps, and sodium salts. The manufacture of pulp and paper, textiles, and synthetic materials all depend on sodium hydroxide.
  5. Water Treatment: To balance the pH values of water and wastewater, sodium hydroxide is employed in water treatment procedures. Through precipitation processes, it is used to neutralize acidic water and remove heavy metals.
  6. Petroleum Industry: Sodium hydroxide is a chemical that is used in the refinement process of crude oil and petroleum products to eliminate impurities and neutralize acidic components.
  7. Food Industry: Sodium hydroxide is used in the food industry for a number of tasks, including as processing food products, cleaning and sanitizing equipment, and regulating pH levels during food processing. It is employed in the preparation of some foods, including chocolate, cocoa, and olives.
  8. Pharmaceuticals: Sodium hydroxide is used to make medicines and drugs, including antacids and painkillers, in the pharmaceutical industry.
  9. Cleaning solutions: Due to its capacity to dissolve grease and fats, sodium hydroxide is a frequently used ingredient in domestic cleaning solutions as drain cleaners, oven cleaners, and degreasers.
  10. Pulp and paper industry: To enable the creation of paper and cellulose goods, lignin in wood fibers is broken down during the pulping process using sodium hydroxide.
  11. Aluminum Industry: The Bayer method, which uses sodium hydroxide to produce alumina from bauxite ore, is utilized in the aluminum industry.
  12. Textile Industry: The process of mercerization, which increases the tensile strength, luster, and dye affinity of cotton fibers, uses sodium hydroxide in the textile industry.
  13. Making soap: The saponification process, which creates soap from fats and oils, relies heavily on sodium hydroxide. It produces soap and glycerol when it combines with triglycerides (fats). In many different sectors and daily life, soap is utilized extensively for cleaning.
  14. Decontamination and Sterilization: Sodium hydroxide is sometimes used to clean and disinfect surfaces and equipment in medical and laboratory environments. It has a strong ability to eliminate germs and other diseases.
  15. Hair Relaxers and Depilatory Creams: Sodium hydroxide is utilized in cosmetic and personal care products to break down keratin proteins, which aids in straightening or removing undesired hair.
  16. Production of Biodiesel: To produce biodiesel, sodium hydroxide is utilized as a catalyst in the transesterification reaction, which turns animal or vegetable fats into biodiesel.
  17. Paper Industry: To generate paper pulp, lignin, a component of wood, is broken down in the paper industry using sodium hydroxide.
  18. Textile Dyeing: To change the pH of dye baths and aid in dye fixing, sodium hydroxide is employed in textile dyeing operations.

Sodium hydroxide hazards:

Although it is a useful ingredient for many operations, it also offers serious risks if handled or applied incorrectly. The sodium hydroxide hazards are described in full below.

sodium hydroxide hazards (skin burn) sodium hydroxide hazards (skin burn)
  1. Corrosive Characteristics: The serious corrosive properties of sodium hydroxide are one of its main risks. It may quickly erode and dissolve a wide range of substances, including metals, skin, and organic things. It may also cause painful and severe chemical burns when it comes into contact with human skin or eyes because of the sodium hydroxide hazards.
  2. Skin and Eye Irritation: Sodium hydroxide has a strong irritating effect on the skin and eyes. Skin redness, irritation, and burns can result from even a brief exposure to the toxin. If the eyes are exposed to it, it can seriously harm the eyes and, if left untreated, could possibly result in permanent blindness.
  3. Environmental Risks: Sodium hydroxide hazards can affect aquatic life and ecosystems if they are released into the environment. It might affect the aquatic environment and possibly harm aquatic creatures by increasing the pH values in water bodies.
  4. Metal Reactivity: Aluminum, zinc, and tin are just a few of the metals that react with sodium hydroxide to produce dangerous hydrogen gas. Hydrogen bubbles may occur as a result of this reaction, and if they come into contact with an open flame or spark, they could catch fire.
  5. Dangerous Chemical Reactions: Sodium hydroxide hazards may include dangerous chemical interactions with a variety of substances, including organic compounds, acids, and oxidizing agents. Explosions, fires, and toxic gases can all result from these reactions.
  6. Inhalation Risks: Inhaling fumes or a mist of sodium hydroxide can cause respiratory irritation and damage to the respiratory system. Long-term exposure to the chemical in high quantities can injure the lungs and cause respiratory discomfort, which are a type of sodium hydroxide hazards.
  7. Highly Reactive with Water: Sodium hydroxide reacts vigorously with water, generating a sizable amount of heat. When the chemical comes into contact with water or moisture, this exothermic reaction may cause the emission of steam or heat, providing additional risks.
  8. Spillage and Containment: If sodium hydroxide spills or leaks, it must be contained as soon as possible to stop additional exposure and spread. When handling the spill, the proper personal safety equipment should be used, and the affected area should be thoroughly cleansed and neutralized using the right substances to protect yourself from sodium hydroxide hazards.
  9. Inhalation and Ingestion: Exposure to sodium hydroxide fumes or ingestion of the substance can result in severe health consequences, such as respiratory troubles, gastrointestinal distress, and systemic poisoning.
  10. Chemical Burns: Chemical burns to the skin and mucous membranes can result from direct contact with sodium hydroxide. The exposure’s intensity and duration affect the burns’ severity.
  11. Storage Risks: To guarantee safety and prevent accidents, sodium hydroxide must be stored correctly.  It should be stored away from incompatible substances, such as acids, which can react violently with caustic soda, leading to the release of toxic gases.
  12. Fire Risk: Although sodium hydroxide alone is non-flammable, it can quicken the burning of other combustible substances. It can make a fire more intense and spread faster when combined with combustible materials.

These are the main sodium hydroxide hazards.


Sodium hydroxide (NaOH) can be synthesized through various methods. Some of the common methods include:

Laboratory Synthesis:

In a lab setting, sodium metal and water can be used to create sodium hydroxide. It results in the production of hydrogen gas and sodium hydroxide.

Na + H2O → NaOH + H2

Caustic Soda Process:

The process of making caustic soda, commonly referred to as the chlor-alkali process, is the one most frequently employed in the production of sodium hydroxide (NaOH). Brine, a concentrated sodium chloride (NaCl) solution, is electrolyzed during this procedure. The following are the main steps in the caustic soda method:

  • Making Brine: A concentrated sodium chloride solution is made, often containing 25–30% NaCl. A convenient and affordable source of sodium ions for the process is brine.
  • Electrolysis: The brine solution is introduced into an electrolytic cell, which has a cathode and anode compartment divided by a membrane or a diaphragm. The membrane or diaphragm prevents the sodium hydroxide and chlorine gas from combining, produced at cathod and anode respectively.
  • Reaction at Cathode: Sodium ions (Na+) in the brine are drawn to and move to the cathode (negative electrode). Water molecules are reduced at the cathode by the electrons that are taken from the cathode to form hydroxide ions (OH-).

2 H2O + 2 e- → 2 OH- + H2

The overall reaction at the cathode can be represented as follows:

               2 H2O + 2 Na+ + 2 e → 2 NaOH + H2

  • Anode Reaction: Chloride ions (Cl-) in the brine are drawn to and move to the anode (positive electrode). Chlorine gas (Cl2) is produced by the chloride ions oxidation at anode.

               2 Cl → 2 e+ Cl2

  • Product Separation: A concentrated solution of the sodium hydroxide generated at the cathode is collected. In order to make PVC (polyvinyl chloride) and other chemicals, the chlorine gas produced at the anode is trapped and employed in a number of industrial processes.
  • Purification: Depending on the particular needs of the intended use, the collected sodium hydroxide solution may go through additional purification procedures to eliminate contaminants and modify the concentration.

A few of the industries that employ sodium hydroxide are soap and detergent production, pulp and paper production, water treatment, and chemical manufacturing.

Mercury Cell Process:

The Castner-Kellner process, commonly referred to as the mercury cell process, is an earlier technique for electrolysis-based sodium hydroxide (NaOH) synthesis. Although the more ecologically friendly membrane cell process has essentially replaced this technique, it is nevertheless important to comprehend its fundamental principles. The operation of the mercury cell is described in detail below:

  1. Setup of an Electrolysis Cell: The steel container that serves as the cathode and the graphite anode make up the electrolysis cell utilized in the mercury cell method. Concentrated sodium chloride (NaCl), sometimes referred to as brine, is poured into the cell. At the bottom of the cell, a layer of liquid mercury is positioned, and a steel mesh screen is immersed in the mercury to act as the cathode. The anode is positioned above the brine solution.
  2. Cathode Reaction: When an electric current is applied to the cell, sodium ions (Na+) from the brine migrate to the cathode and are reduced on the steel mesh screen coated with liquid mercury. Sodium amalgam, which is a combination of sodium and mercury, is created when sodium ions are reduced.

              2 Na+ + 2 e- → 2 Na (sodium amalgam)

  1. Mercury Reaction: The sodium amalgam formed at the cathode reacts with the excess liquid mercury to form a sodium-mercury amalgam.

              Na (sodium amalgam) + Hg (mercury) → Na(Hg)

  1. Anode Reaction: At the anode, chloride ions (Cl-) from the brine are oxidized to form chlorine gas (Cl2).

               2 Cl- → Cl2 + 2 e-

  • Mercury Recycling: The sodium-mercury amalgam that forms at the cathode is periodically taken out of the cell and placed in a different chamber. The sodium-mercury amalgam and water are combined in this chamber, where the sodium reacts to make sodium hydroxide and regenerate the liquid mercury.

               2 Na(Hg) + 2 H2O → 2 NaOH + Hg (liquid mercury)

  • Sodium Hydroxide Collection: While the regenerated liquid mercury is used in the electrolysis cell, the concentrated sodium hydroxide solution produced in the chamber is collected.
  • Chlorine Collection: The anode produces chlorine gas, which is collected and used in a number of industrial processes, including the creation of PVC (polyvinyl chloride) and other chemicals.

Although the mercury cell method is efficient in producing sodium hydroxide, the usage of poisonous mercury raises serious environmental issues. As a result, the more ecologically friendly and sustainable membrane cell technique has mainly taken its place. Liquid mercury is not required in the membrane cell method because a membrane or diaphragm is used to separate the cathode and anode compartments.

Diaphragm Cell Process:

One of the current processes for producing sodium hydroxide using electrolysis is the diaphragm cell technique. The outdated mercury cell process can be replaced with an environmentally friendly one. A thorough explanation of the diaphragm cell process is provided below:

  1. Setup of an Electrolysis Cell: The diaphragm cell is formed up of a rectangular steel container with two compartments, each separated by a porous asbestos or other suitable material diaphragm. This diaphragm divides the cathode and anode compartment. the graphite anode is placed in anode compartment while the steel is placed in cathode compartment.
  2. Brine Solution: The anode compartment is filled with a concentrated sodium chloride (NaCl) solution known as brine. The diaphragm keeps the anode and cathode compartments from coming into direct contact, preventing the mixing of sodium hydroxide and chlorine gas produced at the cathode.
  3. Cathode reaction: Na+ ions move towards the cathode compartment when electric current is applied to cell and at cathode the water molecules reduced to hydrogen gas and hydroxide ions.

               2 H2O + 2 e- → H2 (hydrogen gas) + 2 OH-

  1. Anode Reaction: In anode compartment, chloride ions (Cl-) from the brine are oxidized to form chlorine gas (Cl2).

               2 Cl- → Cl2 + 2 e-

  1. Diaphragm Function: The porous diaphragm prevents the migration of chloride ions and chlorine gas while allowing sodium ions to move from the anode compartment to the cathode compartment. By separating them, the chlorine gas is kept in the anode compartment and is prevented from reacting with the sodium hydroxide that is created at the cathode.
  2. Sodium Hydroxide Collection: In the cathode compartment, concentrated sodium hydroxide that has formed at the cathode is collected. If necessary, additional processing procedures might be used to further purify and concentrate it.
  3. Chlorine Collection: The anode produces chlorine gas, which is collected and used in a number of industrial processes, including the creation of PVC (polyvinyl chloride) and other chemicals.
  4. Hydrogen Gas: As a byproduct of the process, the hydrogen gas produced at the cathode is typically evacuated or captured for use.

Despite minimizing its negative effects on the environment, the diaphragm cell technique is effective in producing sodium hydroxide and chlorine gas. It is a safer and more environmentally friendly way to produce sodium hydroxide since it doesn’t use hazardous mercury to divide the anode and cathode compartments.

Membrane Cell Process:

The membrane cell procedure is a cutting-edge and sustainable way to electrolyze sodium hydroxide (NaOH) and produce it. Since it does not use mercury and does not require a porous diaphragm, it is seen to be an improvement over the mercury cell and diaphragm cell methods.

  1. Setup of an Electrolysis Cell: An ion-selective membrane divides a rectangular steel container into two compartments, creating the membrane cell. This unique membrane, known as a Nafion membrane, essentially separates the cathode compartment from the anode compartment.
  2. Brine Solution: The anode compartment is filled with a concentrated sodium chloride (NaCl) solution known as brine. Sodium ions (Na+) can travel through the Nafion membrane, while other ions, such as chloride ions (Cl-) and hydroxide ions (OH-), cannot travel.
  3. Cathode Reaction: When an electric current is provided, sodium ions from the brine go through the Nafion membrane towards the cathode compartment. At cathode water molecules are reduced to hydroxide ions and hydrogen gas.

             2 e- + 2 H2O → hydrogen gas (H2) + 2 OH

  1. Anode Reaction: In the anode compartment, chloride ions from the brine are oxidized to form chlorine gas.

               2 Cl → Cl2 + 2 e-

  1. The Nafion membrane’s function: Its function is to restrict the migration of chloride ions and chlorine gas while permitting sodium ions to pass through from the anode compartment to the cathode compartment. The sodium hydroxide that is created at the cathode is protected from reaction by the chlorine gas being separated and collected in the anode compartment.
  2. Sodium Hydroxide Collection: In the cathode compartment, concentrated sodium hydroxide that has formed at the cathode is collected. The Nafion membrane ensures the purity of the sodium hydroxide product by preventing hydroxide ions from migrating back to the anode compartment.
  3. Chlorine Collection: The anode produces chlorine gas, which is collected and used in a number of industrial processes, including the creation of PVC (polyvinyl chloride) and other chemicals.
  4. Hydrogen Gas: As a byproduct of the process, the hydrogen gas produced at the cathode is typically evacuated or captured for use.

In comparison to conventional techniques, the membrane cell process has various benefits, including improved safety, enhanced energy efficiency, and reduced environmental impact. The procedure ensures the manufacturing of high-quality sodium hydroxide without the use of hazardous mercury or porous diaphragms by using a Nafion membrane. As a result, in many current industrial applications, the membrane cell approach is now the preferred way to synthesize sodium hydroxide, and it is also beneficial to protect from sodium hydroxide hazards.


In conclusion, sodium hydroxide is a useful chemical with many industrial uses, but because of its corrosive and toxic qualities, it must be handled with extreme care and caution. To reduce the sodium hydroxide hazards, appropriate safety measures are required, such as the use of suitable PPE, sufficient ventilation, and safe handling practices. To guarantee their own safety and to reduce the sodium hydroxide hazards, employees handling sodium hydroxide should get the appropriate training and education about its risks and safe handling practices.

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