The Pros and Cons of Quaternary Ammonium Disinfectants (QACs)

Quaternary ammonium compounds (QACs) are a kind of widely used cationic surfactants. They are formed by the substitution of hydrogen atoms of ammonium groups by alkanes or aromatic hydrocarbon groups. The general formula is (R4N+) X-, where R is a hydrocarbon group or a phenyl group, and X- is a halogen ion such as Cl-, Br- and so on. The properties of QACs are determined by the structure and properties of their substituted R groups, which can be divided into four categories, namely, alkyltrimethylammonium compounds (ATMACs) and dialkyldimethlammonium compounds (DADMACs), benzylalkyldimethylammonium compounds (BACs) and heterocyclic ammonium compounds (HACs). Generally speaking, the longer the carbon chain contained in QACs substituted for the R group, the weaker its water solubility and polarity, and the stronger its non-polarity. When the chain of the same length is contained, QACs without phenyl are more polar than those with phenyl. Because of its good surface activity and bactericidal effect, QACs are widely used in industrial, agriculture, food industry and medical care industry. Among them, ATMACs (the main products are cetyl, octadecyl trimethyl halide), DADMACs (the main products are didodecyl, dihexadecyl, dioctadecyl alkyl dimethyl halide amines) and BACs (the main product is phenyl dodecyl halide amines) are the most widely used, with a history of more than 60 years, and the current annual consumption exceeds 500,000 tons, and it is still increasing year by year. QACs can kill most bacterial propagules and fungal viruses. The ingredients are mild and non-irritating. They are suitable for disinfection in hospitals, schools, and homes. The Advantages and Disadvantages of Quaternary Ammonium Disinfectants Advantages: Low bactericidal concentration of quaternary ammonium salt disinfectants; colorless, low odor, no corrosive bleaching effect; relatively stable performance, light and heat resistance, easy to store; low toxicity. Disadvantages: Quaternary ammonium salt disinfectants are low-efficiency disinfectants. They are still unable to kill microorganisms such as fungi, tuberculosis, hydrophilic viruses, and bacterial spores. In addition, the price is also expensive. Factors Affecting the Disinfection Effect of Quaternary Ammonium Salt Disinfectants The main factors affecting the disinfection effect of quaternary ammonium salt disinfectants are: Organic substancesrnSince organic substances, such as serum, can reduce the bactericidal concentration of quaternary ammonium salts, organic substances on the surface of the object must be removed before disinfection with quaternary ammonium salt disinfectants. AntagonismrnQuaternary ammonium salt disinfectant is a cationic surfactant, which can be combined with anionic surfactant to reduce the effective concentration of quaternary ammonium salt disinfectant. Common anionic surfactants in life include soap, washing powder, etc. In the process of using quaternary ammonium salt disinfectants, such substances should be avoided. EnvironmentrnQuaternary ammonium salt disinfectants are easily affected by factors such as pH, water quality, temperature, etc., and can exhibit better antibacterial and bactericidal effects in an alkaline environment. Some quaternary ammonium salt disinfectants, such as benzalkonium bromide, can react with metal ions in high-hardness water to reduce the effective concentration of quaternary ammonium salt, thus failing to achieve the corresponding disinfection effect. Therefore, when preparing quaternary ammonium salt disinfectants, distilled water should be used and the pH should be adjusted to alkaline in order to achieve the best disinfection effect.