Degree of alkyl chain branching of various commercially available detergent alkylates, including straight chain type, branched chain type and mixture thereof, was studied by means of high-resolution nuclear maenetic resonance. and an explicit correlation between alkyl chain branching ofdetergent alkylates and biodegradability of their sulf onates was obtained.
The degree of alkyl chain branching in detergent alkylates is expressed by a parameter HCH3-6 ΣH-5, which is obtained by a combination of NMR and gaschromatography, where HCH3 and Σ H - 5 denote the number of methyl hydrogens and the total number of hydrogens in the alkyl chain, respectively.
A plot of this parameter for the alkyl chain branching of detergent alkylates against biodegradability of their sulfonates was found to be almost linear as in Fig.-3.
Use of Hω, which denotes the number of total methyl hydrogens in the alkyl chain, instead of HCH3 in the parameter leads to a lack of the linearlity of the plot of the alkyl chain branching against the biodegradability of sulf onates as in Fig.-4. Whereas, biodegradability of alkylbenzene sulfonates can be more rapidly predicted, since Hω, can be derived only from NMR spectra of hydrogens in the alkyl chain in detergent alkylates.
