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E526 Calcium hydroxide, also known as slaked lime, hydrated lime, or Ca(OH)₂, is a strong inorganic alkaline compound formed when calcium oxide (quicklime) reacts with water, producing a white alkaline material that is widely used in food processing, water treatment, construction, agriculture, and industrial chemical systems because of its ability to neutralize acids, regulate pH, and react with many inorganic and organic substances.
E526 Calcium hydroxide is considered one of the most important calcium-based industrial chemicals.
E526 Calcium hydroxide improves pH control and chemical processing efficiency in many industries.
CAS Number: 1305-62-0
Molecular Formula: CaH2O2
Molecular Weight: 74.09
EINECS Number: 215-137-3
Synonyms: CALCIUM HYDROXIDE, 1305-62-0, slaked lime, hydrated lime, lime hydrate, calcium hydrate, lime water, calcium hydroxide Ca(OH)2, Hydralime, slaked lime, lime milk, Calcarea caustica, INS NO.526, PF5DZW74VN, E-526, CHEBI:31341, hydroxide calcium, 215-137-3, O2 Patch, RefChem:54625, KO2 Ca(OH)2, DTXCID5014410, CHEBI:35150, DTXSID601045142, 620-122-3, Bell mine, Biocalc, Calbit, calcium dihydroxide, Caldic 1000, Calvit, caustic lime, DTXSID7034410, Kalkhydrate, Kemikal, Kentoku K 100, Limbux, milk of lime, NICC 3000, Rhenofit CF, Sa 074, Super Microstar, Yukijirushisakanyo, Ca(OH)2, calcium dihydoxide, BTTE, calcium II hydroxide, Kalziumhydroxid, Loeschkalk, geloeschter Kalk, Calcium Hydroxide FCC, CaO2, hydrated lime ISO, calcium 2+ hydroxide, LIME WATER VANDF, SCHEMBL1759, calcium hydroxide ACS grade, CALCIUM HYDROXIDE II, CALCIUM HYDROXIDE MI, CALCIUM HYDROXIDE FCC, CALCIUM HYDROXIDE JAN, CALCAREA CAUSTICA HPUS, CALCIUM HYDROXIDE HSDB, CHEMBL2106388, CALCIUM HYDROXIDE VANDF, INS-526, CALCIUM HYDROXIDE MART, CALCIUM HYDROXIDE USP-RS, CALCIUM HYDROXIDE WHO-DD, AKOS015903965, FC47052, CALCIUM HYDROXIDE EP MONOGRAPH, CALCIUM HYDROXIDE USP MONOGRAPH, DB-023009, NS00074455, F492444, Q182849, Calcium Hydroxide FCC oxalate ID test 98%+ total alkaliCALCIUMHYDROXIDE,POWDER,REAGENT,ACS, CALCIUMHYDROXIDE,POWDER,USP,EP,BP,JP, CALCIUMHYDROXIDE,TECH(HYDRATEDLIM)(BULK, CALCIUMHYDROXIDE,TECHNICAL, Calcium Hydroxde, Calcium Hydroxide, Powder, Reagent, Calcium hydroxide, 98+%, extra pure, Calcium hydroxide, 95+%, for analysis ACS
E526 Calcium hydroxide consists of calcium ions (Ca²⁺) and hydroxide ions (OH⁻), and when mixed with water it forms an alkaline suspension or solution commonly known as limewater, which has a high pH and can neutralize acidic materials while also participating in precipitation and coagulation reactions.
Although E526 Calcium hydroxide is less soluble and slightly weaker than sodium or potassium hydroxide, it still behaves as a strong base in many industrial systems.
E526 Calcium hydroxide improves controlled alkalinity and reaction stability.
E526 Calcium hydroxide appears as a white powder, granules, or crystalline solid, and it is only slightly soluble in water compared with other hydroxides, which means excess material often remains suspended as a fine white solid in limewater mixtures.
It is stable under dry conditions but slowly reacts with carbon dioxide in air to form calcium carbonate.
E526 Calcium hydroxide improves its usefulness in controlled neutralization and mineral reactions.
E526 Calcium hydroxide functions mainly as an acidity regulator, firming agent, and processing aid, where it is used to neutralize acids, modify texture, and stabilize chemical conditions in industrial and food-related applications.
Its alkaline properties make it highly useful in pH-sensitive systems.
E526 Calcium hydroxide improves process control and material stability.
E526 Calcium hydroxide is widely used in water and wastewater treatment, where it helps neutralize acidic water, soften hard water, and remove impurities by precipitation reactions that convert dissolved contaminants into removable solids.
This makes it important in environmental treatment systems.
E526 Calcium hydroxide improves water purification and environmental management.
E526 Calcium hydroxide is best described as a moderately strong alkaline calcium compound used for pH control, water treatment, food processing, construction, and industrial neutralization because of its ability to regulate acidity, precipitate impurities, and stabilize chemical systems under controlled conditions.
E526 Calcium hydroxide is an inorganic compound with the chemical formula Ca(OH)2.
It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water.
Annually, approximately 125 million tons of calcium hydroxide are produced worldwide.
E526 Calcium hydroxide has many names, including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime.
E526 Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526.
Limewater and milk of lime are common names for a saturated solution of calcium hydroxide.
E526 Calcium hydroxide also plays a major role in controlled mineral precipitation systems, where its moderate alkalinity allows dissolved metal ions and impurities in water to react and form insoluble compounds that can then be separated through sedimentation or filtration, making it extremely useful in industrial wastewater treatment processes that require removal of heavy metals, phosphates, and acidic contaminants without using more aggressive alkalis such as sodium hydroxide.
Because of its lower solubility, it can provide a more gradual and stable alkaline effect in large-scale treatment systems.
E526 Calcium hydroxide improves contaminant removal efficiency and operational stability.
In cement chemistry and historical construction technology, E526 Calcium hydroxide is important because it forms during the hydration of cement and later reacts with atmospheric carbon dioxide to produce calcium carbonate, a process that contributes significantly to the hardening and long-term strength development of lime-based building materials, mortars, and concrete structures used in both ancient and modern architecture.
This slow carbonation reaction has been fundamental in construction engineering for thousands of years.
E526 Calcium hydroxide improves structural durability and material longevity.
In corn processing and nixtamalization, E526 Calcium hydroxide is used in alkaline cooking solutions that chemically modify the outer structure of corn kernels, loosening the hull, softening the grain, and increasing the bioavailability of nutrients such as niacin while also changing flavor and texture characteristics in products like tortillas, tamales, and masa dough.
E526 Calcium hydroxide traditional process remains industrially important in many food systems today.
E526 Calcium hydroxide improves nutritional value and processing quality.
In soil stabilization and civil engineering projects, E526 Calcium hydroxide is mixed with clay-rich soils because it reacts with silicates and aluminates in the ground, reducing plasticity and moisture sensitivity while increasing strength and load-bearing capacity, which makes unstable soils more suitable for roads, foundations, and infrastructure construction.
E526 Calcium hydroxide chemical stabilization process is widely used in geotechnical engineering.
E526 Calcium hydroxide is improves ground stability and construction reliability.
In industrial flue gas desulfurization systems, calcium hydroxide is sprayed or injected into exhaust streams where it reacts with acidic sulfur-containing gases such as sulfur dioxide to form solid calcium sulfite or sulfate compounds that can be removed before atmospheric release, helping industries comply with environmental air quality regulations.
Melting point: 580 °C
Boiling point: 2850 °C
Bulk density: 400kg/m3
Density: 2.24 g/mL at 25 °C (lit.)
Refractive index: 1.574
Storage temp.: +5°C to +30°C
Solubility: 1.7 g/L
Form: Solid
pKa: 12.6 [at 20 ℃]
Color: White
Odor: Odorless
pH range: 12.4
pH: 11.27 (1 mM), 12.2 (10 mM), 12.46 (100 mM)
Water Solubility: 1.65 g/L (20 ºC)
Sensitive: Air sensitive
Merck: 14,1673
Solubility Product Constant (Ksp): pKsp 5.26
Exposure limits: ACGIH TWA 5 mg/m3; OSHA TWA 15 mg/m3 / 5 mg/m3; NIOSH TWA 5 mg/m3
Stability: Stable. Incompatible with strong acids.
Cosmetics Ingredients Functions: BUFFERING
Cosmetic Ingredient Review (CIR): Calcium hydroxide (1305-62-0)
InChI: 1S/Ca.2H2O/h;2*1H2/q+2;;/p-2
InChIKey: AXCZMVOFGPJBDE-UHFFFAOYSA-L
SMILES: O[Ca]O
E526 Calcium hydroxide is a colorless crystal or white powder, obtained when CaO (called lime or quicklime) is mixed, or “slaked” with water.
E526 Calcium hydroxide can also be precipitated by mixing CaCl2 andNaOH.The nameof the natural,mineral formis “portlandite”.
It is a relatively rare mineral, known from some volcanic, plutonic, and metamorphic rocks.
E526 Calcium hydroxide has also been known to be formed in burning coal dumps.
The dust or suspension droplets of calcium hydroxide have a stimulating effect on the mucous membrane, which can cause sneezing and coughing.
As alkali, it can also saponify the fat, absorb water from the skin, dissolve protein, as well as stimulate and corrode the organization.
Moreover, the inhalation of lime dust may cause pneumonia.
The maximum allowable concentration of calcium hydroxide is 5 mg/m3.
Once Inhaling dust, people can inhale water vapor, codeine and Judah auning, or paint mustard cream at the chest, when calcium hydroxide coming into the eyes, people should rinse the eyes as soon as possible with the running water and followed by 5% ammonium chloride solution or 0.01% CaNa2-EDTA solution, and then add 0.5% tetracaine solution dropwise.
While working, people should wear dustproof fiber work clothes, gloves and dust-proof glasses to protect the respiratory organs, and paint grease ointment to prevent dust inhalation.
E526 Calcium hydroxide is also widely used in construction and building materials, where it is an important ingredient in mortars, plasters, and lime-based cements because it reacts slowly with carbon dioxide from air to form calcium carbonate, creating hardened structures that contribute to strength and durability in masonry systems.
This carbonation process has been used in construction for thousands of years.
E526 Calcium hydroxide improves structural stability and long-term durability.
In food processing, E526 Calcium hydroxide is used in certain traditional and industrial applications such as corn treatment for nixtamalization, where alkaline processing helps loosen hulls, improve texture, and increase the availability of nutrients like niacin in corn products used for tortillas and related foods.
E526 Calcium hydroxide process significantly changes the chemical and nutritional properties of the grain.
This improves food texture and nutritional quality.
In sugar refining, it is used to neutralize acidic impurities and help clarify sugar solutions by precipitating unwanted compounds that can then be removed during processing stages.
E526 Calcium hydroxide contributes to cleaner and more stable sugar production systems.
This improves product purity and refining efficiency.
In agriculture and soil treatment, E526 Calcium hydroxide is used to reduce soil acidity and improve pH balance, which supports healthier growing conditions for crops and improves nutrient availability in acidic soils.
This makes it important in agricultural land management.
E526 Calcium hydroxide improves soil productivity and crop performance.
In industrial flue gas treatment systems, it is used to neutralize acidic gases such as sulfur dioxide by converting them into solid calcium salts that can be removed from emissions before release into the atmosphere.
This is important in pollution control systems for power plants and industrial facilities.
E526 Calcium hydroxide improves air quality and environmental protection.
In leather processing, E526 Calcium hydroxide is used during liming operations to remove hair and prepare hides for tanning by breaking down proteins and loosening unwanted tissue materials under alkaline conditions.
This is a critical step in traditional leather manufacturing.
E526 Calcium hydroxide improves hide preparation and tanning efficiency.
In chemical manufacturing, it is used as a reagent to produce calcium salts and other specialty compounds through neutralization and precipitation reactions that require controlled alkaline conditions.
Its moderate alkalinity makes it useful for less aggressive processing compared with stronger hydroxides.
E526 Calcium hydroxide improves reaction control and chemical production flexibility.
In laboratory and educational chemistry, limewater is commonly used as a test for carbon dioxide because dissolved calcium hydroxide reacts with CO₂ to form insoluble calcium carbonate, creating a cloudy appearance that visibly demonstrates gas absorption and precipitation chemistry.
This is one of the classic demonstrations in chemistry education.
E526 Calcium hydroxide improves experimental visualization and teaching value.
In aquaculture and water conditioning, E526 Calcium hydroxide is sometimes used to increase alkalinity and stabilize pH in ponds and aquatic systems, especially in environments where acidic conditions negatively affect aquatic organisms or microbial balance, although dosing must be carefully controlled to avoid harmful pH spikes.
Its calcium content can also contribute to mineral balance in water systems.
E526 Calcium hydroxide improves aquatic environmental management.
In sugar beet and sugar cane refining, E526 Calcium hydroxide is used in clarification stages where it reacts with impurities and non-sugar compounds, helping them precipitate or coagulate so they can be removed before crystallization, leading to cleaner sugar solutions and improved refining efficiency in large-scale sugar production facilities.
This controlled purification process is a critical industrial step.
E526 Calcium hydroxide improves sugar purity and manufacturing performance.
In chemical synthesis and industrial reagent systems, E526 Calcium hydroxide is frequently used when a milder and less soluble alkaline reagent is preferred, particularly in reactions where gradual release of hydroxide ions is beneficial for controlling precipitation rates, reducing excessive heat generation, or limiting aggressive corrosion associated with stronger alkalis.
This makes it valuable in selective chemical processing operations.
E526 Calcium hydroxide improves reaction control and industrial safety.
In environmental remediation projects, E526 Calcium hydroxide can be used to neutralize acidic soils, mine drainage, and contaminated industrial sites because it raises pH and promotes immobilization of certain toxic metal ions through precipitation reactions, reducing their mobility and environmental impact under controlled treatment conditions.
E526 Calcium hydroxide is especially important in mining and waste management industries.
This improves environmental restoration and contamination control.
In laboratory and educational chemistry, E526 Calcium hydroxide solutions are commonly used to demonstrate acid-base reactions, precipitation chemistry, and carbon dioxide detection because the visible formation of calcium carbonate provides a simple and effective way to observe chemical changes directly in classroom experiments.
Its predictable reactions make it ideal for teaching fundamental chemistry principles.
E526 Calcium hydroxide improves scientific education and experimental visualization.
E526 Calcium hydroxide is a versatile alkaline calcium compound used across water purification, environmental remediation, construction, agriculture, food processing, flue gas treatment, civil engineering, sugar refining, and laboratory chemistry because of its controlled alkalinity, precipitation behavior, and ability to neutralize acids while stabilizing materials and removing contaminants in a wide variety of industrial and environmental systems.
Uses Of E526 Calcium hydroxide
E526 Calcium hydroxide Used for preparing bleaching powders, hard water softeners and the disinfecting and clarifying agents of tap water , as well as in building industry.
E526 Calcium hydroxide is used for pharmacy.
E526 Calcium hydroxide is used as rubber and oil industry additives. Used in lubricants for preventing coking, sludge deposition and anti-corrosion. Used as hard water softeners, disinfectants, antacids and so on.
E526 Calcium hydroxide is used as analytical reagents, carbon dioxide absorbents, as well as in organic synthesis
E526 Calcium hydroxide is used for making bleaching powder, hard water softener, depilatory, disinfectant, acid stop agent, astringent and various calcium salts.
E526 Calcium hydroxide is used for carbon dioxide examination and gas absorption. Used for leather hair removal, insecticide and water treatment.
E526 Calcium hydroxide is an inorganic base used to adjust the pH of a product, it can also serve as a topical astringent and alkali in solutions or lotions.
It can burn the skin and eyes.
E526 Calcium hydroxide is mainly used as an acidity regulator, pH control agent, water treatment chemical, and industrial processing aid because of its alkaline properties and ability to neutralize acids, precipitate impurities, and stabilize chemical systems.
In water and wastewater treatment, E526 Calcium hydroxide is used to neutralize acidic water, soften hard water, and remove impurities through precipitation reactions.
E526 Calcium hydroxide helps improve water quality and environmental treatment efficiency.
In construction materials, it is used in mortars, plasters, and lime-based cements where it hardens through carbonation reactions with carbon dioxide in air.
E526 Calcium hydroxide improves structural strength and durability.
In food processing, it is used in nixtamalization of corn to improve texture, processing behavior, and nutrient availability in products such as tortillas and corn-based foods.
This improves food quality and nutritional properties.
In sugar refining, it is used to neutralize acidic impurities and clarify sugar solutions during processing.
This improves product purity and refining performance.
In agriculture, E526 Calcium hydroxide is used to reduce soil acidity and improve pH conditions for crop growth and nutrient absorption.
E526 Calcium hydroxide improves soil management and agricultural productivity.
In flue gas and emission treatment systems, it is used to neutralize acidic gases such as sulfur dioxide in industrial exhaust streams.
E526 Calcium hydroxide improves air pollution control and environmental protection.
In leather processing, it is used in liming operations to prepare hides for tanning by loosening hair and breaking down unwanted proteins.
E526 Calcium hydroxide improves leather processing efficiency.
In chemical manufacturing, it is used to produce calcium-based compounds and participate in neutralization or precipitation reactions.
E526 Calcium hydroxide improves industrial chemical processing flexibility.
E526 Calcium hydroxide is mainly used as an alkaline pH regulator, neutralizing agent, water treatment chemical, construction material additive, and industrial processing aid because of its ability to neutralize acids, precipitate dissolved impurities, stabilize mineral systems, and provide controlled alkalinity in a wide variety of industrial, environmental, agricultural, and food-related applications.
In water and wastewater treatment systems, E526 Calcium hydroxide is used to neutralize acidic water, soften hard water, and remove dissolved contaminants by converting impurities such as heavy metals and phosphates into insoluble compounds that can be removed through sedimentation or filtration processes.
Because it provides a more gradual alkaline effect compared with stronger hydroxides, it is especially useful in large-scale environmental treatment operations.
E526 Calcium hydroxide improves water purification efficiency and environmental safety.
In construction and cement industries, E526 Calcium hydroxide is used in mortars, plasters, lime-based cements, and soil stabilization systems because it reacts with carbon dioxide and mineral components to form hardened structures that improve strength, durability, and long-term stability in buildings, roads, and infrastructure projects.
This reaction has been fundamental in construction engineering for centuries.
E526 Calcium hydroxide improves structural performance and material longevity.
In food processing, E526 Calcium hydroxide is used in nixtamalization of corn, where alkaline treatment loosens hulls, modifies texture, and improves nutrient availability in products such as tortillas, tamales, and masa dough while also changing flavor and processing behavior in beneficial ways.
This traditional alkaline cooking process remains industrially important today.
E526 Calcium hydroxide improves food texture, processability, and nutritional quality.
In sugar refining, E526 Calcium hydroxide is used to neutralize acidic impurities and clarify sugar solutions by promoting precipitation and coagulation of unwanted compounds before crystallization stages, helping produce cleaner and more stable sugar products during industrial refining operations.
E526 Calcium hydroxide is a critical purification step in sugar manufacturing.
This improves product purity and refining efficiency.
In agriculture and soil treatment, E526 Calcium hydroxide is used to reduce soil acidity and improve pH balance in agricultural land, which enhances nutrient availability, microbial activity, and crop growth conditions in acidic soils that would otherwise limit plant productivity.
It also contributes calcium as a mineral nutrient.
E526 Calcium hydroxide improves soil management and agricultural performance.
E526 Calcium hydroxide is used to neutralize acidic gases such as sulfur dioxide in exhaust streams by converting them into solid calcium salts that can be captured and removed before atmospheric release, making it an important chemical in industrial emission control technologies.
This is widely used in power plants and heavy industry.
E526 Calcium hydroxide improves air pollution reduction and environmental compliance.
In leather processing and tanning, E526 Calcium hydroxide is used during liming operations to loosen hair, break down unwanted proteins, and prepare hides for further tanning treatments under controlled alkaline conditions.
This is an essential step in traditional and industrial leather production.
E526 Calcium hydroxide improves hide preparation and tanning efficiency.
In soil stabilization and civil engineering projects, it is mixed with clay-rich soils to reduce plasticity, improve strength, and increase resistance to moisture-related deformation by reacting with silicate and aluminate minerals naturally present in the soil structure.
E526 Calcium hydroxide makes unstable ground more suitable for roads and construction foundations.
E526 Calcium hydroxide improves geotechnical stability and infrastructure reliability.
In environmental remediation systems, E526 Calcium hydroxide is used to neutralize acidic industrial waste, mine drainage, and contaminated soils while also helping immobilize toxic metal ions through precipitation reactions that reduce their environmental mobility and ecological impact.
This is important in mining and waste management operations.
E526 Calcium hydroxide improves contamination control and environmental restoration.
E526 Calcium hydroxide is used to produce calcium salts and participate in neutralization or precipitation reactions where a moderately strong and less aggressive alkaline reagent is preferred over highly corrosive hydroxides such as sodium hydroxide or potassium hydroxide.
Its controlled reactivity makes it useful in selective industrial processing.
E526 Calcium hydroxide improves reaction control and chemical processing safety.
E526 Calcium hydroxide solutions (limewater) are widely used to demonstrate acid-base reactions and carbon dioxide detection because they react visibly with CO₂ to produce calcium carbonate precipitates, making them valuable for teaching chemical equilibrium and precipitation principles.
E526 Calcium hydroxide makes it a classic educational reagent.
This improves scientific demonstration and experimental learning.
E526 Calcium hydroxide is used across water treatment, construction, food processing, agriculture, emission control, leather tanning, environmental remediation, civil engineering, chemical manufacturing, and laboratory science because of its controlled alkalinity, acid-neutralizing ability, and capacity to precipitate impurities and stabilize mineral systems in a broad range of industrial and environmental applications.
Safety Profile Of E526 Calcium hydroxide:
Mildly toxic by ingestion a severe eye irritant.
A skin, mucous membrane, and respiratory system irritant mutation data reported.
Causes dermatitis dust is considered to be a significant industrial hazard.
A common air contaminant. Violent reaction with maleic anhydride, nitroethane, nitromethane, nitroparaffins, nitropropane, phosphorus.
Reaction with polychloiinated phenols + potassium nitrate forms extremely toxic products.
E526 Calcium hydroxide is considered a moderately hazardous alkaline substance, and although it is less aggressive than sodium hydroxide or potassium hydroxide, it can still cause significant irritation and chemical damage because of its strong alkalinity and ability to react with moisture in tissues and materials.
Proper handling and protective equipment are required during industrial use.
E526 Calcium hydroxide reduces exposure risks and workplace hazards.
The most common hazard is eye and skin irritation, where contact with powder or wet mixtures can cause redness, dryness, burning sensations, and in severe cases chemical burns, especially during prolonged exposure or when mixed with water to form highly alkaline suspensions.
Eye exposure can lead to serious injury if not treated quickly.
E526 Calcium hydroxide makes direct contact potentially dangerous.
Inhalation of dust may cause respiratory irritation, including coughing, throat dryness, sneezing, and breathing discomfort, particularly in dusty industrial or construction environments where fine lime particles become airborne during handling.
Long-term occupational exposure may worsen respiratory irritation.
E526 Calcium hydroxide requires proper ventilation and dust protection.
Ingestion of large amounts can cause irritation or burns to the mouth, throat, and digestive tract because of its alkaline nature, potentially leading to nausea, abdominal pain, or tissue damage depending on concentration and exposure level.
Accidental ingestion requires medical attention.
E526 Calcium hydroxide makes improper handling hazardous.
E526 Calcium hydroxide also reacts with acids in neutralization reactions, and while these reactions are less violent than with stronger hydroxides, they still release heat and may create splashing hazards if large quantities are mixed improperly.
