An In-depth Guide to Monoethanolamine (MEA)
Table of Contents
What you will learn
📋 What You'll Learn
This guide walks you through an in-depth guide to monoethanolamine (mea) with detailed instructions.
An In-Depth Guide to Monoethanolamine (MEA)
The bifunctional amino alcohol powering carbon capture, gas sweetening, surfactant formulation, and industrial cleaning worldwide.
The Chemical Architecture of a Multifunctional Molecule
In the landscape of industrial chemistry, few compounds offer the sheer functional versatility of Monoethanolamine (MEA). As the simplest of the ethanolamines, MEA is a cornerstone chemical essential for processes ranging from large-scale gas purification and carbon capture to the formulation of high-performance surfactants and cosmetics.
MEA's remarkable utility stems from its unique bifunctional structure: a primary amine group (-NH₂) and a primary alcohol group (-OH) on the same molecule. This "dual personality" makes it simultaneously a strong base, an effective solvent, and a reactive chemical building block.
Amine Group (-NH₂)
Provides strong basic (alkaline) properties. Readily reacts with and neutralizes acidic compounds like CO₂ and H₂S.
Alcohol Group (-OH)
Makes MEA an effective solvent, contributes hygroscopic properties, and provides a site for esterification and other reactions.
Complete Miscibility
Fully miscible with water and most organic solvents, making it exceptionally versatile in formulation and process chemistry.
At room temperature, MEA is a viscous, colorless to slightly yellow liquid with a mild ammonia-like odor. Its high boiling point (170°C) means low evaporative losses during industrial processing, which translates to both safety advantages and economic benefits.
The Cornerstone Application: Acid Gas Scrubbing and Carbon Capture
The single largest global use for MEA is in "gas sweetening" — the removal of acidic gases, primarily hydrogen sulfide (H₂S) and carbon dioxide (CO₂), from sour gas streams in natural gas processing and petroleum refining. This same chemistry makes MEA a leading candidate for post-combustion carbon capture from power plant flue gas.
The Chemistry of Reversible Absorption
MEA works as a chemical absorbent through a two-stage continuous loop:
1. Absorption (Scrubbing)
Sour gas passes through 15-30% MEA solution in an absorber column. The amine group reacts with CO₂ and H₂S, forming water-soluble salts (carbamates). The "sweet" gas exits the top.
2. Regeneration (Stripping)
The "rich" MEA solution is pumped to a regenerator and heated with steam (110-120°C). Heat reverses the reaction, releasing pure CO₂/H₂S. The "lean" MEA is cooled and recycled.
The Carbon Capture Equation
2 RNH₂ + CO₂ ⇌ RNH₃⁺ + RNHCOO⁻
This reversible reaction is the foundation of amine scrubbing. MEA's high reactivity with CO₂ gives it the fastest absorption kinetics among the common alkanolamines — critical for processing large gas volumes efficiently.
Why MEA Dominates Gas Treating
- Highest absorption capacity per mole among common ethanolamines (0.5 mol CO₂ per mol MEA)
- Fastest reaction kinetics — primary amines react with CO₂ faster than secondary or tertiary amines
- Lowest molecular weight in its class, meaning more reactive amine per kilogram of chemical purchased
- Well-understood chemistry with decades of operational data and proven performance
- Cost-effective compared to specialty amines and physical solvents
Operational Consideration
MEA solutions are more corrosive than DEA or MDEA solutions, particularly when CO₂ loading exceeds 0.35-0.40 mol/mol. Most operators limit MEA concentration to 15-20 wt% and add corrosion inhibitors. Stainless steel construction is recommended for high-temperature sections of the process.
MEA as a Versatile Formulating Agent
Beyond gas treatment, MEA's dual functionality makes it an essential ingredient in a vast array of formulated products. When MEA reacts with fatty acids, it forms ethanolamine soaps — powerful surfactants with both hydrophilic (water-loving) and lipophilic (oil-loving) character.
Surfactants and Emulsifiers
Industrial Cleaners & Degreasers
MEA-based surfactants emulsify and lift heavy oils, greases, and carbon deposits from metal, concrete, and equipment surfaces. Used in CIP (clean-in-place) formulations.
Cosmetics & Personal Care
Creates stable oil-in-water emulsions in creams and lotions. Acts as a pH adjuster and foam booster in shampoos, body washes, and liquid soaps.
Metalworking Fluids
MEA's alkalinity neutralizes acidic components that cause corrosion. It forms protective molecular films on metal surfaces, extending tool and workpiece life. Common in cutting fluids and coolants.
Additional Industrial Applications
| Industry | Application | MEA's Role |
|---|---|---|
| Pharmaceuticals | Drug synthesis, pH buffering | Reaction intermediate, buffer agent in injectable formulations |
| Textiles | Dye dispersal, fabric finishing | Dispersing agent for dyes, softening agent in fabric treatment |
| Wood Treatment | Preservative penetration | Helps copper-based preservatives penetrate deep into wood fibers |
| Agriculture | Herbicide formulation | Neutralizer and solubilizer in glyphosate and 2,4-D formulations |
| Concrete | Grinding aids | Reduces energy consumption in cement grinding by 5-10% |
| Electronics | Flux cleaning | Removes rosin and no-clean flux residues from PCB assemblies |
The Ethanolamine Family: MEA vs. DEA vs. TEA
Understanding the differences between the three commercial ethanolamines helps you select the right compound for your application. Each additional hydroxyl group changes the molecule's reactivity, basicity, and physical properties.
| Property | MEA (Mono-) | DEA (Di-) | TEA (Tri-) |
|---|---|---|---|
| Formula | C₂H₇NO | C₄H₁₁NO₂ | C₆H₁₅NO₃ |
| Amine Type | Primary | Secondary | Tertiary |
| Molecular Weight | 61.08 | 105.14 | 149.19 |
| Basicity (pKa) | 9.50 | 8.88 | 7.76 |
| CO₂ Reactivity | Highest (fastest) | Moderate | Lowest (slowest) |
| Corrosiveness | Highest | Moderate | Lowest |
| Best For | Bulk CO₂/H₂S removal, strong cleaners | Refinery gas treating, corrosion inhibitors | Cosmetics, cement grinding aids |
Selection Tip
Choose MEA when you need maximum absorption capacity and fastest reaction kinetics (gas treating, carbon capture, heavy-duty cleaning). Choose DEA for lower-corrosion gas treating with moderate regeneration energy. Choose TEA for gentle pH buffering and emulsification in cosmetics and personal care products.
Critical Safety & Handling Protocols
MEA is a corrosive substance that can cause severe skin burns and serious eye damage. Its vapors irritate the respiratory system. Strict adherence to safety protocols is non-negotiable.
GHS Hazard Classifications
H302: Harmful if swallowed • H312: Harmful in contact with skin • H314: Causes severe skin burns and eye damage • H332: Harmful if inhaled. Always consult the Safety Data Sheet (SDS) before handling.
Personal Protection
Chemical-resistant gloves (butyl rubber or neoprene), splash-proof goggles, face shield, chemical-resistant apron. Respiratory protection with organic vapor cartridge if outside fume hood.
Ventilation
Handle in well-ventilated areas or under fume hoods with local exhaust ventilation. MEA's low vapor pressure reduces inhalation risk at room temperature, but heating significantly increases vapor generation.
Storage
Store in tightly sealed, corrosion-resistant containers (stainless steel or HDPE) in a cool, dry, well-ventilated area. Keep away from strong acids and oxidizing agents. MEA absorbs CO₂ from air, gradually losing effectiveness.
First Aid: In case of skin or eye contact, immediately flush with copious amounts of water for at least 15-20 minutes. Remove contaminated clothing. Seek prompt medical attention. Do not attempt to neutralize with acid — the exothermic reaction can worsen burns.
For comprehensive chemical storage and handling guidelines, see our dedicated safety resource.
Buyer's Guide: Grades, Specifications & Procurement
Commercial MEA is typically available in 85% and 99%+ purities. The grade you need depends on your application's sensitivity to impurities.
| Parameter | Technical Grade | High Purity / ACS |
|---|---|---|
| Purity | ≥ 99.0% | ≥ 99.5% |
| Water Content | ≤ 0.5% | ≤ 0.2% |
| Color (APHA) | ≤ 25 | ≤ 10 |
| DEA + TEA | ≤ 0.5% | ≤ 0.1% |
| Best Use | Gas treating, cleaning, metalworking | Analytical, pharmaceutical, cosmetic |
Why Supplier Quality Matters
In gas treating, impurities like DEA and TEA change absorption kinetics and can cause foaming. In cosmetics, color and odor directly affect product quality. Alliance Chemical provides lot-specific Certificates of Analysis (COA) with every shipment so you can verify specifications before use.
Related Reading
MEA in Carbon Capture Technology
Deep dive into how MEA drives cutting-edge post-combustion carbon capture and green chemistry applications.
Guide to Neutralizing Spent Caustic Baths
Comprehensive procedures for safely neutralizing alkaline industrial solutions.
Sodium Hydroxide in Modern Industry
How NaOH — another powerful base — shapes manufacturing, water treatment, and chemical processing.
Mastering pH Balance
Deep dive into pH control using acids, bases, and buffers across industrial and agricultural applications.
Your Partner for High-Performance Amines
From large-scale carbon capture to precision cosmetic formulation, Alliance Chemical provides high-quality MEA and the full family of ethanolamines, backed by technical expertise and lot-specific COAs.
Shop Monoethanolamine Browse Bases & Caustics Consult Our ExpertsFrequently Asked Questions
What is monoethanolamine (MEA) and what is it used for?
MEA (HOCH₂CH₂NH₂) is a versatile organic amine used primarily for CO₂ and H₂S removal from natural gas and refinery streams (gas sweetening), as a surfactant ingredient in personal care products, a corrosion inhibitor in metalworking fluids, a pH adjuster in cosmetics, and a cement grinding aid in concrete production.
How does MEA remove CO₂ from gas streams?
MEA reacts reversibly with CO₂ to form a carbamate: 2 MEA + CO₂ → MEA carbamate + MEAH⁺. The CO₂-rich solution is heated to 120°C in a stripper column, releasing pure CO₂ and regenerating lean MEA for reuse. This amine scrubbing process achieves 85-95% CO₂ removal from industrial gas streams.
What safety precautions are needed when handling MEA?
MEA is corrosive to skin and eyes—wear chemical-resistant gloves, splash goggles, and protective clothing. It has a PEL of 3 ppm (TWA) and a strong ammonia-like odor. Store in sealed containers away from oxidizers and acids. In case of skin contact, flush with water for 15+ minutes. Ensure adequate ventilation in all work areas.
What is the difference between MEA, DEA, and MDEA in gas treating?
MEA (monoethanolamine) has the fastest CO₂ reaction rate and highest capacity per mole but degrades in the presence of COS and CS₂. DEA (diethanolamine) is less reactive but more stable. MDEA (methyldiethanolamine) selectively removes H₂S over CO₂, enabling selective treating. Many facilities use activated MDEA (MDEA + piperazine) for optimized performance.
