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Understanding Alkaline Cleaners: Their Function and Effectiveness

alkaline foam cleaning

What Are Alkaline Cleaners

Alkaline cleaners are cleaning agents formulated with powerful bases like potassium hydroxide and sodium hydroxide. They can break down fats, oils, grease, and other protein-based deposits.
 
Often, dispersing agents are included in the formulation to prevent the redeposition of chelants or dissolved dirt, which could otherwise corrode metal surfaces and lead to rust formation.

How Do Alkaline Cleaners Work

alkaline cleaning solutions

Successful metal cleaning depends on using alkaline cleaners, which are primarily made up of phosphates, silicates, and caustic compounds. These cleaners have a stable blend of active agents on their surfaces, making them highly efficient at removing contaminants. They are not only among the most effective options available, but they are also notable for their affordability, especially in automated cleaning processes. Alkaline cleaners are excellent at eliminating stubborn, moist soils when applied via spraying or dissolved in warm water.

They operate through various mechanisms:

  1. Saponification: Alkaline cleaners facilitate the removal of oils, fatty acids, and greases by transforming them into water-soluble compounds.
  2. Solvent Action: This feature enables alkaline cleaners to effectively dissolve surface oils on metals.
  3. Emulsification: Alkaline cleaners suspend oil particles, facilitating their easy rinsing from the surface.
  4. Detergency: Active wetting agents reduce surface tension on metals, enhancing the penetration and displacement of soil.
  5. Deflocculation – The cleaning solution disperses contaminants into very fine particles, suspending them in the solution.

While alkaline cleaners are well-known for their ability to fight dirt, selecting the appropriate type and using the correct amounts is important to ensure optimal efficacy in industrial settings. 

Components of Alkaline Cleaners

alkaline builders caustic soda

Alkaline cleaners comprise several key components, each serving specific functions in the cleaning process.

Alkaline Builders

The term “alkaline builders” refers to a wide range of chemicals including caustic soda (NaOH), caustic potash (KOH), phosphates, silicates, and carbonates, which provide the alkalinity for the cleaner. High-alkalinity products turn fats and vegetable oils into soluble soaps. Additionally, alkaline salts neutralize acidic contaminants and help disperse oils.

Caustic Soda (NaOH) and Caustic Potash (KOH)

Caustics such as KOH and NaOH are the most common type of alkalinity builders. They are highly alkaline, with a pH ranging from 12 to 14. These substances saponify fats and work together with surfactants to disperse contaminants. It’s important to note that this type of builder should not be used on soft metals such as aluminum and zinc.

Silicates

Silicates have a medium alkalinity of pH 11 to 12.5 and contribute to detergency. They prevent the corrosion of soft metals but become insoluble at a pH below 10.

Phosphates

Phosphates have slightly lower alkalinity values (pH 9.5 to 11.5) and offer better cleaning power than the other listed builders. They also protect soft metals and help prevent hard water ions from interfering with the cleaning process.

Carbonates

Mildly alkaline carbonates (with a pH ranging from 9 to 9.5) are primarily used to neutralise acidic contaminants and maintain a specific pH range in solutions.

Wetting Agents

Wetting agents, such as surfactants and synthetic detergents, help remove contaminants by reducing the surface tension of the solution. This allows the cleaner to effectively reach under the contaminant and displace it from the metal surface. Once the contaminant is in the solution, the wetting agent forms an emulsion, preventing it from re-depositing onto the cleaned part. Surfactants have one end soluble in water (hydrophilic) and one soluble in oil (hydrophobic), enabling them to create an oil-water emulsion that can be easily rinsed away. 

Chemistry Behind Alkaline Cleaning

what are surfactants
Emulsification is the process of dispersing one liquid (such as oil) into another liquid (such as water) to form a stable mixture called an emulsion. Surfactants stabilise the interface between the two liquids by forming a layer of molecules around the dispersed droplets, preventing them from coalescing.

Saponification

One of the fundamental chemical reactions in alkaline cleaning is saponification. This reaction involves the hydrolysis of fats and oils (triglycerides) into glycerol and fatty acid salts (soap) in the presence of an alkali (such as sodium hydroxide or potassium hydroxide). Alkaline cleaners break down fats and oils by converting them into water-soluble soap molecules, which can then be easily rinsed away with water.

Emulsification

Alkaline cleaners contain surfactants, which are molecules with both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions. These surfactants help to emulsify oils and grease by surrounding oil droplets with their hydrophobic tails, while their hydrophilic heads interact with water molecules. This emulsification process disperses the oil or grease into tiny droplets, allowing them to be suspended in water and washed away.

Dispersing and Chelating Agents

Alkaline cleaners often contain dispersing and chelating agents, which help prevent the redeposition of dissolved soils and contaminants onto surfaces. Dispersing agents work by keeping soil particles suspended in the cleaning solution, preventing them from reattaching to the surface being cleaned. Chelating agents bind to metal ions present in soils, preventing them from forming insoluble complexes that could lead to staining or surface damage.

pH Adjustment

The high pH of alkaline cleaners plays a crucial role in their cleaning effectiveness. The alkaline environment helps to break down and dissolve acidic soils, such as mineral deposits, rust, and scale. Additionally, the high pH facilitates the saponification reaction by providing the necessary conditions for the hydrolysis of fats and oils.

Complexation

Some alkaline cleaners contain complexing agents that form complexes with metal ions present in soils. These complexes prevent them from reacting with other compounds or interfering with the cleaning process. These complexes are water-soluble and can be easily rinsed away with the cleaning solution. 

Benefits of Using Alkaline Cleaners

alkaline cleaning agent

Effective Contaminant Removal

Alkaline cleaners are more effective in removing solid contaminants than organic chlorinated solvents. This efficacy is attributed to their alkaline nature, which allows them to break down and emulsify various types of soils and contaminants, including grease, oils, fats, and other organic substances.

Heavy-Duty Cleaning

Alkaline cleaners excel at tackling tough stains, soils, and contaminants, making them ideal for heavy-duty cleaning tasks. They are commonly used in industrial facilities, commercial kitchens, automotive workshops, and other environments where thorough cleaning is required.

High pH

The high pH level of alkaline cleaners helps to neutralise acidic substances and contaminants, such as oils, grease, and food residues. This makes them particularly effective for cleaning surfaces that have been soiled with acidic substances.

Compatibility

Alkaline cleaners are generally compatible with various cleaning equipment, including pressure washers, steam cleaners, and scrubbing machines. This makes them easy to integrate into existing cleaning processes and equipment.

Cost-Effectiveness

Alkaline cleaners are highlighted as being less expensive than organic chlorinated solvents. This cost-effectiveness can be advantageous for businesses and industries looking to reduce cleaning expenses without compromising on cleaning performance. The lower cost of alkaline cleaners may result from the availability and affordability of their raw materials, as well as their generally lower concentration requirements for effective cleaning. 

Environmental Friendliness

One of the significant advantages of alkaline cleaners over organic chlorinated solvents is their environmental friendliness. Unlike chlorinated solvents, which can pose environmental and health risks due to their toxicity and potential for bioaccumulation, alkaline cleaners are considered safer and more environmentally sustainable. They typically have lower toxicity levels, are biodegradable, and have minimal impact on ecosystems and human health when used and disposed of properly.

ORAPI RECOMMENDS: 

ALCALATHER is a potent foam cleaner that is a blend of alkalis, biodegradable surfactants, corrosion inhibitors, and water conditioning sequestrants. It is specifically formulated for the daily and periodic deep cleaning of equipment in the food, beverage, and dairy industries.
ALCALATHER generates a dense foam that adheres to both vertical and horizontal surfaces, effectively dissolving and removing fats, proteins, and dirt. 

Selecting an Alkaline Cleaner

alkaline drain cleaner
When selecting a cleaner, it’s important to consider the type of metal being processed to prevent damage. This is especially crucial when working with aluminium, zinc, and certain exotic metals.
 
The cleaner must be formulated to effectively remove the specific contaminants it will encounter. Simple, light-rust preventive oils and water-soluble coolants can be easily removed with mildly alkaline cleaners at moderate temperatures. However, more durable corrosion prevention compounds like waxes and heavy-oil rust inhibitors require a more aggressive product, typically a high-alkaline cleaner with a good oil-solubilising surfactant package at high temperatures.
 
The cleaner must also be suitable for the mechanics of the operating system. Immersion cleaners usually require surfactant systems that are different from spray cleaners. Additionally, the use of chelates is often necessary to counteract the undesirable effects of hard water salts.
It’s also important to consider the form of the cleaner. Liquids are easy to use and can be automated, while powders are usually added manually but are more cost-effective for most operations.

Conclusion

In summary, alkaline cleaners are essential for industrial and commercial cleaning due to their powerful base formulations and various active agents, which effectively break down and remove a wide range of contaminants such as fats, oils, and grease. These cleaners use mechanisms such as saponification, emulsification, and solvent action, along with dispersing and chelating agents, to enhance their efficacy and prevent redeposition of dissolved dirt. Their high pH levels and compatibility with different cleaning systems make them versatile and cost-effective solutions. Additionally, their environmental friendliness and safety over organic solvents highlight their importance in sustainable cleaning practices. 

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