Question

Structurally biodegradable detergent should contain ______.

Answer 1

Hint:Detergents: These are the sodium or potassium salts of large alkyl chains which have a sulfonate group at their end. They can readily dissolve in hard water i.e.; they give lather in the hard water. Some examples of detergent are deoxycholic acid, sodium lauryl sulphate, etc.

Complete answer:
Based on the type of alkyl chains present, the detergent is divided into two types:
1.Biodegradable detergents: These are the type of detergents in which the alkyl chain is linear i.e., there should be no branching in the alkyl groups of the chain. These detergents can easily be destroyed by bacteria. Example of a biodegradable detergent is sodium alkyl benzene sulphonate.
2.Non-biodegradable detergents: These are the types of detergents in which the alkyl chain is branched. These detergents cannot be destroyed by bacteria and hence are one of the sources of pollution. Example of a non-biodegradable detergent is cetyl methyl ammonium bromide.
Hence, structurally biodegradable detergents should contain a linear hydrocarbon (alkyl) chain
Additional information-
Detergents can also be classified on the basis of charge produced on dissolving it in the solution.
Cationic detergents: These are the detergents which form a positive charge ion in the solution. These have a positive charge at the end of the long alkyl chains. Example:
\[{\left[ {C{H_3}{{(C{H_2})}_n} - N{{(C{H_3})}_2} - C{H_3}} \right]^ + }B{r^ - }\]
Anionic detergents: These are the detergents in which the long alkyl chains are negatively charged species. The negatively charged hydrocarbon group is lyophilic in nature i.e., can easily dissolve in water. Example: sodium lauryl sulphate.

Note:
Detergents are readily soluble in hard water because the sulfonate group present at the end does not make bonds with the ions that are present in the hard water. These are majorly used for household cleaning, fuel additives and biological reagents.