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Colloid and Surface Science Aspects in Disinfectants

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Title: Colloid and Surface Science Aspects in Disinfectants


1
Colloid and Surface ScienceAspects in
Disinfectants
  • Reginald Jacques
  • Garret Lau
  • Carla Ng
  • Pintu Saha
  • University at Buffalo, Department of Chemical
    Engineering

2
Overview
  • Major Uses
  • The Disinfectant Market
  • Product Considerations
  • Disinfecting Agents
  • Colloids in Disinfectants
  • Interactions and Structure-Property Relationships
  • Disinfectants of the Future

3
What is a disinfectant?
  • Agent that kills actively growing micro-organisms
    (bacteria, viruses, fungi, etc.) but does not
    kill their spores.
  • Purpose prevention of sickness caused by these
    microorganisms.

4
Application of Disinfectants
  • Food industry sanitize food preparation areas,
    preservative functions
  • Drinking water typically chlorine, other
    organic oxidizers
  • Medical sterilization of equipment, facilities
  • Household cleaners (kitchen, bathroom,
    multipurpose), soaps, detergents
  • Other industries paints, inks, cosmetics
    (serves as preservative)

5
Product Specifications
  • Selective toxicity want to kill bacteria,
    viruses, other pathogens remain safe to humans
    and general environment
  • Government regulations must abide by rules and
    regulations imposed by EPA, FDA
  • Household considerations
  • multipurpose products disinfectant combined with
    surfactant for grease removal, or moisturizers as
    in soaps
  • dispersive quality aerosol or spray for coverage
    and adhesion to hard surfaces (countertops, bath,
    toilet, etc)

6
Further Considerations
  • Marketing - Between 1997-1999, manufacturers
    introduced 700 new antibacterial or disinfectant
    products half of 2.1 billion cleanser market in
    US bacterial resistance?
  • Cost (2-4 for 32 oz. Shower cleaner) compare
    active ingredient of brand names with generic
  • Processing/Packaging liquid detergents, soaps
    (plastic bottles) aerosol spray (aluminum cans)
    polymerized disinfectants (chemically
    incorporated into fabric or material)

7
Ingredients of Disinfecting Cleaners
  • Builders Tie up the hardness minerals in water
    so they do not interfere with the cleaning action
    of the surfactant
  • Builders are subdivided into into three
    categories Sequestering, precipitating and Ion
    exchange builders.
  • Abrasive Contribute to the mechanical
    effectiveness of scouring cleanser consist of
    small mineral particles.
  • examples Silica, feldspar, calcite
  • Acids Dissolve calcium and metal salt in tub,
    tile, sink and toilet bowl cleaners.
  • Type of acids Phosphoric, Hydrochloric,
    hydroxyacetic acids
  • Alkalis maintain pH at a desirably high level
    during cleaning play a crucial role in removing
    solid grease.
  • Types of alkalis are sodium Hydroxide, Sodium
    metasilicate, sodium carbonate

8
Other important ingredients
  • Antimicrobial agents Destroy bacteria and
    viruses, by interfering with their metabolism or
    destroying their cell walls.
  • Examples Alcohol, sodium hypochlorite, iodine,
    pine oil etcetera.
  • Bleaching agents Oxidize the soil and stain to a
    more easily removable form. Attack the soil and
    destroy bacterial viruses and mold.
  • Sodium hydroxide is very effective for that
    purpose.
  • Colorants Give an appealing characteristic to
    the product, can also be tracers.
  • Enzymes Break down the soil into a simpler form
    that can be removed.
  • Polymer They are very helpful in floor care
    product, they protect the surface and provide
    shine.

9
Other important ingredients
  • Processing aids keep the product homogeneous
    under different storage conditions.
  • Most used processing aids are Clays, polymers,
    Sodium Silicate and Sodium Sulfate
  • Preservatives Protect the product against decay,
    discoloration,oxidation and bacterial attack
  • Typical preservatives includebutylated hydroxy
    toluene, glutaraldehyde and so on.
  • Organic solvent Help in removing spots without
    leaving any residue.

10
Type of colloids
  • Hydrophobic Colloids is a colloid in which there
    is a strong attraction between the dispersed
    phase and the continuous phase (water)
  • Hydrophilic Colloidsis a colloid in which there
    is a lack of attraction between the dispersed
    phase and the continuous phase (water)
  • Association Colloids They are described as
    molecule that has two part in their
    configuration., a hydrophobic part and a
    hydrophilic part

11
Association Colloids
  • Mainly used in the fabrication of disinfectant
  • Examples of this type of colloid micelles,
    reverse micelles, vesicles, micro-emulsions.

12
SURFace ACTive AgeNT
  • They are often portrayed as having a head and a
    tail.
  • Molecule that adsorbs at the surface and/or
    interface.
  • They are described as being amphiphilic.
  • Types of surfactants anionic, cationic,
    nonionic, amphoteric.

13
Anionic Surfactant
  • Are used in the fabrication of disinfectant
  • They are used all over the place, and their
    composition represent almost half of all the
    other surfactant are made of.
  • They are sometimes used in conjunction with
    nonionic to provide greater stability.
  • Type of nonionic surfactants that are used in
    disinfectant are
  • Fatty acids (soaps)
  • Sodium Oleate, Sodium Palmitate, Sodium Myristate
    etcetera.
  • Alkyl Sulfates
  • Sodium Dodecyl Sulfate (SDS)
  • Other commonly used Anionic Surfactant
  • Alkyl Benzene Sulfonates, 2-Alkyl Phosphate,
    Sodium di(2-ethylhexyl) Sulfosuccinate
    (Aerosol-OT)
  • Long term exposure can lead to skin irritation

14
Main Components and Compositions of Disinfectants
for Household
  • Alcohol Compounds
  • Chlorine Compounds
  • Iodine Compounds
  • Quaternary Ammonium Compounds

15
Alcohols
  • Inhibition increases with the chain length.
  • Methyl Alcohol
  • Not included in most household goods.
  • Ethyl Alcohol
  • Effective germicide for vegetative pathogens
  • Isopropyl Alcohol
  • Effective germicide for an antimicrobial agent
  • Products
  • Food
  • Health Care Products

16
Chlorine Compounds
  • Antibacterial action of chlorine compounds
    dependent upon their capacity for releasing
    active chlorine
  • Sodium Hypochlorite
  • Chlorine Dioxide
  • Products
  • Drinking Water
  • Cleaners

17
Iodine Compounds
  • Aqueous Solutions
  • Alcoholic Solutions
  • Iodophric Preparations
  • Products
  • Drinking Water
  • Health Care Products Antiseptic

18
Quaternary Ammonium Compounds
  • Aliphatic long-chain ammonium salt
  • Owe their surface activity and antibacterial
    qualities primarily to the presence of aliphatic
    long-chain amino groups.
  • Products
  • Contact Lens Solution

19
Designing an Effective Disinfectant
  • Know your dirt
  • What type of surface?
  • Soil effect on disinfectant action
  • Oily residues are impervious to water and often
    contain germs.
  • Bacteria can form biofilms to protect against
    attack.
  • Consumer considerations
  • Fragrance
  • Irritants
  • Environmental Concerns

20
Overcoming Biofilms and Organic Residues
  • Disinfectants disrupt bacterial cell function.
  • Many common disinfectants are effective biocides,
    but are inactivated by organics.
  • Components must be added to aid disinfectants in
    reaching and affecting bacterial cells ?
    Surfactants

21
Mechanism of Antibacterial Activity
  • Adsorption onto cell surface
  • Diffusion through cell wall
  • Binding to the cytoplasmic membrane
  • Disruption of the cytoplasmic membrane
  • Release of cytoplasmic constituents
  • Cell death

22
How Surfactants Aid Disinfectants
  • Surfactants can help by
  • Removing surface residues and biofilms
  • Aiding the germicide action of disinfectants
  • Some surfactants are biocides themselves.
  • Surfactants can facilitate disinfectants by
    disrupting the bacterial cell membrane.

23
Structure-Property Relationship
  • Structure of surfactant will dictate how it
    interacts with bacteria.
  • Example
  • Surfactants containing polar ethylene oxide
    chain
  • Chain too small, no disruption
  • Chain too long, no disruption
  • Chain same order as lipid bilayer, cell membrane
    disruption? cell death.

24
Structure-Property (continued)
  • Critical Micelle Concentration (CMC) and
    germicidal activity are linked
  • CMC antibacterial properties
  • CMC related to hydrophobicity, charge
    distribution, molecule shape.
  • These characteristics affect the interaction of
    surfactant with microbial cell.

25
Disinfectants of the Future
  • Understanding what makes disinfectants work leads
    to new improved formulations
  • Environmentally friendly disinfectants
    glucose-based cationic surfactants
  • Polymers as disinfectants
  • disinfectant coatings
  • insoluble disinfectants

26
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