Colloidal and Surface Phenomena of Liquid Laundry Detergent

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Colloidal and Surface Phenomena of Liquid Laundry
Detergent





Dan Boek Erika Indivino Katie Marso Karey
Smollar April 18th, 2002


 

 

 

 
 
                   
 

                   





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History

• Clothes first cleaned by mechanical means
• Production of soaps
• First produced in the 15th century
• Combine fats and sodium hydroxide
• Renewable, biodegradable resources
• Negative affects of hard water

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History

• Synthetic detergents
• First produced in 1916 in Germany
• Introduction of margarine
• Large bodies of water covered in foam
• Production took off in the U.S. after WWII
• Mainly used for dishwashing and fine fabrics

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History

• 1946, first all-purpose laundry detergent
• Included surfactants and builders
• Combinations became more complex
• Sodium triphosphate (STP)
• Very effective builder
• Use restricted in 1960s because it caused
  eutrification in rivers
• New additives are continually being introduced

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History

• Liquid laundry detergent
• 1970s, became popular in the U.S.
• More convenient for consumers
• Easier to handle
• Do not contain bleaching agents
• Remove stains better at lower temperatures
• Sales have soared above powders in last decade
• Have reached 50/50 market split in the U.S.

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Design Considerations

• Excellent soil removal
• Low sensitivity to hard water
• Builders prevent calcium and magnesium deposits
• Good dispersion properties
• Liquid detergents spread easily
• Soil antiredeposition capability
• Surfactants keep soils in suspension

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Design Considerations

• High solubility in water
• Liquid detergents dissolve faster than powders
• Foaming
• Psychological affect, foam means detergent is
  working
• Odor
• Perfumes and fragrances
• Color

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Design Considerations

• Toxicity
• Exposure through skin, ingestion, inhalation
• Environmental affect
• Use of phosphates
• Convenience
• Easier to pour, direct application on stains
• Cost

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Types of Fabrics

• Fabrics require specialized soil removal
• Textile versus synthetic fabrics
• Different calcium content
• Wettability due to hydrophobic and hydrophilic
  nature
• Complexing agents react differently with each
  type of soil

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Types of Fabrics

• Sodiumtriphosphate
• Effectiveness dependent on hydrophilic/hydrophobic
  nature of the fiber
• Efficient removal of soils from synthetic or
  cotton garments, which are hydrophilic
• Minimal affect on hydrophobic textile fibers
• Different fabric and soil types are dealt with by
  using a mixture of compounds in detergents

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History

• Tablets
• Directed to elderly and students
• New and expensive
• Hold 25 of market in some European countries
• Pouches
• Introduced in April 2001
• Liquid detergent in polyvinyl alcohol skin
• Dissolves in seconds, leave behind no residue

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Main Components
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Anionic Surfactants

• Tetrapropylenbenzene (TPS)
• -used in earlier stage production of detergents
  to first replace soap
• -branching increases the wetting ability but
  limits effective detergency

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• Linear Alkylsulfonate (LAS)
• -demonstates good detergency ability and is not
  very sensitive to water hardness

Sodium linear alkylsulfonate (LAS)  
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• Secondary Alkanesulfonates (SAS)
• -highly soluable surfactant demonstrating fast
  wetting properties and chemical stability of
  alkali and acids

Secondary Alkanesulfonates (SAS).  
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Olefinsulfonates (AOS)

• produced using alkaline hydrolysis process
• shows less sensitivity to water only under
  certain conditions such as chain length and type
  of chemical bonding

    
   
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Nonioinic Surfactants

• An essential ingredient found in smaller
  quantities which are used for stabilizing the
  micelle formations and prevent redeposition

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Advantages of Builders

• Enhances effects of surfactants
• Used to reduce water hardness, Mg2 and Ca2
• Enables the production of cheaper detergent while
  retaining the cleaning properties

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Types of Builders

• Trisodium phosphate is the most common type of
  builder
• Zeolites Molecular formula Na2OAl2O34.5H2O.
• -water insoluble builder
• -10 micrometer diameter
• -reduces soil redeposition by replacing calcium
  and magnesium ions with sodium

Figure 3 Trisodium Citrate (NaCit)
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Enzymes

• Help with the removal dried in stain from milk,
  cocoa, blood, egg yolks and grass
• Enzymes commonly used are proteolytic, amylolytic
  and lipolytic
• Enzymes cause hydrolysis of peptide, glucosidic,
  or ester linkages

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Stabilizers

• Prevent redeposition of negatively charged
  particles back on the neutral fabric surfaces
• Sodium carbomethyl cellulose (SCMC)
• Molecular weight is between 20,000 and 500,000
• -Attaches itself to the fibers adding to the
  negative

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Other Additives

• Optical Brighteners
• -Used to brighten fabric appearance by converting
  ultra violet light into longer wavelengths of
  visible blue light
• Fragrances
• Alcohols
• Water

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Contact Angle
soil-water interface
Soil
?
Water
fabric-water interface
fabric-soil interface
Fabric
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Young Equation

• After surfactants are added ?FW ?SW 0
• Interfacial tension between soil and fabric
  remains constant, so ?FS gt ?FW
• Tgt90 degrees
• Contact area between soil and fabric 0

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Roll-Up

• As Tgt90 degrees, the roll-up mechanism takes place

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Without Surfacant

• Without surfactant, surface tensions remain
  constant, T lt 90 degrees
• The soil is partially removed by mechanical
  agitation

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Packing Parameter

• Packing parameter
• pv/aolc
• aosurface area of headgroups
• V volume of hydrocarbon chains
• lo maximum length of chains

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Packing Geometry
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Multilamellar Structure

• Headgroup area diminishes in the presence of salt
  ions, NaCit
• ½ gt p gt 1 so structure is bi-layer
• Continuous lamellar crystalline structure

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Multilamellar Vesicles

• Bilayers form multalamellar vesicles to minimize
  hydrocarbon chain and solvent interactions
• Unilamellar vesicle

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Multilamellar Vesicles
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Flocculation

• Water is a poor solvent with salt ions present
• Chain length decreases due to poor solvency
• Van der Waals forces
• Flocculation and phase separation result

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Decoupling Polymer

• Decoupling polymer
• Hydrophylic backbone and hydrophobic side chains
• Side chains dissolve in oil
• Backbone dissolves in water
• Steric repulsion causes the lamellar droplets to
  repel, hindering flocculation

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Steric Repulsion
Poor solvent without decoupling polymers
Poor solvent with decoupling polymers
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Particulate Soil

• METHODS OF REMOVAL
• Mechanical Energy is the primary type of removal
  and used to enhance anti-redeposition
• Potential Energy barriers is greatest near the
  surface, DLVO Theory
• Using Anioinc surfactant to create electrical
  Charge on the surfactant and fiber causing
  repulsion

Diagram, PE vs. distance
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Potential Energy vs. pH Diagram

• Potential of various fibers as a function of pH
  a) Wool b) Nylon c) Silk d) Cotton e) Viscose
  

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Calcium Containing Soil

• Found on textile fabric surfaces
• Effective detergency is dependent on type of
  washing solvent used
• Increases water hardness which decreases the
  solubility
• Slight solubility can cause calcium deposit
  break-up

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Types of Fabrics

• Cotton, Synthetic, textile
• Different hydrophobic/hydrophilic nature
• Effective detergency is dependent of
  wettability of the cloth and the type of
  complexing agent used
• Cleaning mixed soils on blending fabrics cause
  complementing effects

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Manufacturing

• Liquid detergents are produced either in a batch
  reactor or a continuous blending process.

• Surfactants
• STPP/Zeolite
• Sodium Sulphate
• Sodium Perborate
• Sodium Carbonate
• Sodium Silicate
• Minors

Mixing and Homogenizing
Liquid Detergent
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Packaging

• 3 Main Purposes
• Maintain quality of detergent
• Supply detergent information
• Make handling easy

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Packaging

• Company Considerations
• Compatibility
• Cost
• Safety
• Waste
• Convenience

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Packaging

• Typical bottles are recyclable plastic
• Gradually, companies are adding a percentage of
  recycled plastic to their bottles.
• Generally 25 recycled material
• Concentrated detergents
• Refillable bottles
• Refill bottles 65-90 smaller than original
  container

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Environmental Concerns

• Adjust to environmentally-friendly washing
  machines
• Reduced
• Water
• Energy
• Temperature
• Water consumption
• Minimize amount required for detergent to
  function
• Adapt formula to wash in poor conditions

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Liquid Detergent Sales Continue to Grow
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Market Sales

• Liquid detergent sales top powders in 1998
• 3 billion sold in liquid
• 1.8 billion sold in powder
• Liquids more popular due to convenience and
  better performance

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Market Breakdown
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