CITRIC ACID

Citrate is the salt of citric acid, a weak organic acid. Citric acid's ability to chelate metals makes it useful in soaps, laundry detergents and cleaning products.

  • Function and benefits

    What is its function and benefits?
    Citric acid is a chelator which is more effective on magnesium than
    calcium ions used especially for liquid detergents (DG Environment).Citric acid is also used as a builder for phosphate-free, heavy-duty detergents and hard surface cleaners. (Ref: Cleanright) It is also a natural preservative/conservative and a buffering agent (Ref: Wikipedia)

    By chelating the metals in hard water, it lets these cleaners produce foam and work better without need for water softening. (Ref: Wikipedia) In addition to its water hardness sequestration performance, citrate also acts in the washing machine as a deflocculant for soil particles. Citrate stabilizes other detergent ingredients such as enzymes. In dish detergents, citrate prevents water spotting and film formation. (Ref: Ingredient Information Sheet)

    How does it work?
    It functions by sequestering water-hardness ions, thereby inhibiting the formation of sparingly soluble calcium and magnesium salts of surfactants. (Ref: Ingredient Information Sheet)

  • Chemical structure and composition

    Citric acid

    Citric acid (C6H8O7) is a water soluble organic solid. The acidity of citric acid results from the three carboxylic groups. Having a pKa1 of 3.13 it is considered as a weak acid. (Ref: HERA) Citrate (C6H7O7 -) is the conjugate base of citric acid. (Ref: Wikipedia)

  • Product / Category: where is it used?

    Citrate is ubiquitous in nature; it is a natural constituent and common metabolite of most organisms. Lemon juice for example contains 4 to 8% citric acid. Citrate is also used as a food additive. (Ref: Ingredient Information Sheet)
    Citric acid is an active ingredient in household cleaners. A kitchen cleaning solution with a 6% concentration of citric acid for example will remove hard water stains from glass without scrubbing. (Ref: Wikipedia). Table 1 lists household cleaning applications and typical finished product concentration ranges of citric acid (anhydrous and mono-hydrate) and its tri-sodium salt.
    Table 1: These figures are based on a survey among 8 detergent manufacturers for the European Union 15+3 (+3 being Iceland, Switzerland and Norway) in 2002. The total consumption in HERA applications is estimated to be at 103,000 tons in 2002 (as Citric Acid)

    Product Application Range of Citric Acid (anhydrous, monohydrate) and/or its salts in various products.
    Laundry detergents 0-10%
    Laundry additives 0-55%
    Fabric conditioners <1%
    Machine- / Hand dishwashing detergents 0-45%
    Surface Cleaners 0-30%
    Toilet Cleaners 0-7%

    Citric acid is also used in industry, where it is used to dissolve rust from steel and in many special technical applications, as well as in pharmaceutical preparations (Ref: HERA & Wikipedia)
  • Ingredient safety and information

    AISE-CEFIC published a human and environmental risk assessment for citric acid.
    The available data confirm the low acute and (sub)chronic toxicity profile of citric acid and its salts. The NOAEL for repeated dose toxicity (for rats) is 1200mg/kg/d. It is not suspected of being a carcinogen nor a reprotoxic or teratogenic agent. Citric acid is not mutagenic in vitro and in vivo, and its sensitizing potential is seen as low. Therefore it is admitted that the use of citric acid in household laundry and cleaning products raises no safety concerns for consumers. (Ref: HERA)
    Citric acid and its salts are chemical substances with a very favourable ecological profile. (Ref: HERA) All EC/LC50 data are comprised between 200 and 10,000 mg/L. (Ref: Ingredient Information Sheet) Moreover, citrate is rapidly biodegradable under aerobic and anaerobic conditions. Therefore, due to the very low aquatic toxicity and the ready biodegradability, wide dispersive use of citric acid and its salts do not present a hazard to the environment and are not harmful to aquatic organisms. (Ref: HERA).
    Ingredient information sheet (PDF file)
    Read the full risk assessment in www.heraproject.com

  • References

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