Perchloroethylene
Perchloroethylene (PERC) is a widely used solvent in the dry cleaning industry due to its powerful degreasing and stain-removing properties.
What is Perchloroethylene (PERC)?
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Chemical Name: Tetrachloroethylene
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Formula: C₂Cl₄
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Type: Non-flammable, chlorinated solvent
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Appearance: Colorless liquid with a sweet, ether-like odor
How PERC is Used in Dry Cleaning
1. Cleaning Process Overview:
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Clothes are loaded into a dry cleaning machine, which looks like a large front-loading washer.
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Instead of water and detergent, PERC is used as the cleaning solvent.
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The solvent dissolves oil, grease, and organic stains without damaging delicate fabrics like wool, silk, or rayon.
2. Cycle Steps:
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Wash: PERC is pumped into the drum and circulated through the clothes.
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Extract: The solvent is drained and extracted via spinning.
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Dry: Clothes are dried with warm air, and the solvent is collected, condensed, and recycled for reuse.
Dosage
Why PERC is Preferred (Historically):
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Powerful cleaning agent for oils and greases
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Non-flammable, making it safer for industrial use
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Gentle on fabrics, preventing shrinkage and color fading
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Recyclable within the machine, reducing waste
Precautions
Health & Environmental Concerns:
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Toxic if inhaled in large amounts or over time (linked to liver, kidney, and nervous system effects)
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Classified as a possible human carcinogen
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Requires well-ventilated, sealed systems and PPE for operators
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Strictly regulated in many countries (e.g., banned or phased out in California, EU restrictions)
Alternatives to PERC in Modern Dry Cleaning:
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Hydrocarbon solvents (less aggressive, more eco-friendly)
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Liquid CO₂ cleaning
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Siloxane-based solvents (e.g., GreenEarth®)
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Professional wet cleaning (water-based with special machines and detergents)
Conclusion:
Perchloroethylene remains effective but is increasingly being replaced due to safety and environmental concerns. Dry cleaners using PERC must comply with strict safety protocols and environmental regulations.