Calcium hydroxide, commonly known as slaked lime or hydrated lime, is a white, odorless powder with the chemical formula Ca(OH)₂. It is widely used across various industries due to its alkaline properties and versatility.
Table of Contents
- Chemical Properties and Composition
- Production Process
- Applications in Construction
- Role in Water Treatment
- Agricultural Uses
- Food Industry Applications
- Medical and Dental Uses
- Environmental Remediation
- Use in the Paper and Pulp Industry
- Chemical Manufacturing
- Safety and Handling Precautions
- Storage and Stability
- Regulatory Standards
- Frequently Asked Questions (FAQ)
Chemical Properties and Composition
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Molecular Formula: Ca(OH)₂
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Appearance: White powder or colorless crystals
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Solubility: Slightly soluble in water, forming a basic solution
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pH: Approximately 12.4 in saturated solution
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Melting Point: 580°C
These properties make calcium hydroxide an effective agent in neutralizing acids and as a precursor in various chemical reactions.
Production Process
Calcium hydroxide is produced through the hydration of calcium oxide (quicklime):
CaO + H₂O → Ca(OH)₂
This exothermic reaction results in a fine, dry powder used in numerous applications.
Applications in Construction
In the construction industry, calcium hydroxide is integral in
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Mortar and Plaster: Enhances workability and durability.
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Soil Stabilization: Improves load-bearing capacity of soils.
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Autoclaved Aerated Concrete (AAC): Acts as a key ingredient in lightweight building blocks.
Its ability to react with carbon dioxide to form calcium carbonate contributes to the strength and longevity of building materials.
Role in Water Treatment
Calcium hydroxide plays a crucial role in water purification processes:
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pH Adjustment: Neutralizes acidic water.
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Softening: Removes hardness by precipitating calcium and magnesium ions.
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Flocculation: Aids in the removal of impurities and suspended solids.
Its use ensures safe and clean water for industrial and municipal purposes.
Agricultural Uses
In agriculture, calcium hydroxide is utilized for:
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Soil Amendment: Raises soil pH, improving nutrient availability.
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Pest Control: Acts as a fungicide and insecticide.
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Animal Waste Treatment: Reduces odor and pathogen levels in manure.
These applications enhance crop yields and promote sustainable farming practices
Food Industry Applications
Calcium hydroxide is approved for use in food processing:
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Nixtamalization: Treats corn to improve nutritional value and flavor.
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Sugar Refining: Clarifies raw juice from sugarcane or sugar beets.
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Pickling Agent: Maintains firmness of pickled vegetables.
Its designation as E526 indicates its safety and efficacy in food applications.
Medical and Dental Uses
In the medical field, calcium hydroxide is employed in:
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Dentistry: Used as a lining material in cavity preparations and root canal treatments due to its antibacterial properties.
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Antacid Formulations: Neutralizes stomach acid in over-the-counter medications.
Its biocompatibility makes it suitable for various therapeutic applications.
Environmental Remediation
Calcium hydroxide is effective in environmental cleanup efforts:
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Acid Mine Drainage Treatment: Neutralizes acidic waters from mining operations.
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Heavy Metal Precipitation: Removes toxic metals from industrial effluents.
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Sludge Stabilization: Reduces pathogen levels in sewage sludge.
These uses contribute to pollution control and environmental protection.
Use in Paper and Pulp Industry
In paper manufacturing, calcium hydroxide is involved in:
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Pulping Process: Assists in the chemical recovery cycle.
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pH Control: Maintains optimal conditions for paper production
Its role ensures the efficiency and quality of paper products.
Chemical Manufacturing
Calcium hydroxide serves as a precursor or reactant in producing:
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Calcium Salts: Such as calcium stearate and calcium hypochlorite.
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Polymer Additives: Acts as a stabilizer in plastics.
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Petroleum Refining: Used in the removal of impurities.
Its versatility makes it valuable in various chemical processes.
Safety and Handling Precautions
While calcium hydroxide is generally safe, proper handling is essential:
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Protective Equipment: Use gloves, goggles, and masks to prevent skin and eye contact.
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Ventilation: Ensure adequate airflow when handling powders.
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Storage: Keep in a dry, cool place to prevent moisture absorption.
Adhering to safety guidelines minimizes health risks.
Storage and Stability
Calcium hydroxide should be stored:
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In Airtight Containers: Prevents reaction with carbon dioxide in the air.
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Away from Moisture: Maintains its chemical integrity.
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In Cool Conditions: Prolongs shelf life and effectiveness.
Proper storage ensures product quality over time.
Regulatory Standards
Calcium hydroxide complies with various international standards:
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Food Additive Regulations: Recognized as safe (GRAS) by the FDA.
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Environmental Guidelines: Approved for use in water treatment by the EPA.
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Agricultural Use: Permitted under USDA organic standards for specific applications
These approvals underscore its safety and utility across industries.
Frequently Asked Questions (FAQ)
Q1: Is calcium hydroxide safe for use in food?
Yes, when used in accordance with food safety regulations, calcium hydroxide is safe and approved for various food processing applications.
Q2: How does calcium hydroxide improve soil quality?
It neutralizes acidic soils, enhancing nutrient availability and promoting better crop yields
Q3: Can calcium hydroxide be used for household water treatment?
While it’s effective in large-scale water treatment, household use should be approached with caution and professional guidance.
Q4: What precautions should be taken when handling calcium hydroxide?
Use appropriate personal protective equipment, ensure good ventilation, and store it properly to prevent moisture absorption.
Q5: Where can I purchase high-quality calcium hydroxide?
You can explore and purchase calcium hydroxide from Istay Kimya. Visit the Calcium Hydroxide page.