Nonionic detergent degradation. II. Thin‐layer chromatography and foaming properties of alkyl phenol polyethoxylates

In Part I of this series (1) a study of the degradation of a number of commercially available alcohol polyethoxylates is described. This paper describes the application of the same procedures to the less degradable class of alkyl phenol polyethoxylates. It appears that, for these materials, the rate and extent of degradation is dependent on the environment in which the degradation occurs. Experiments are described that were carried out under neutral and high pH conditions, but it may well be that other variations in the environment could influence the degradation rate. Slow degradation was observed under conditions comparable with those used for the alcohol polyethoxylates, for example, a common alkyl phenol 9‐ethoxylate initially at a concentration of 5 mg per liter showed approximately 50% loss after six weeks. No degradation residues of the polyethylene glycol type and no additional acid degradation products of the types derived from the alcohol ethoxylates were observed. The only visual evidence of degradation was a retardation of the spots on the thin‐layer plates, and it was most readily observed on chromatograms prepared so that they showed a resolved series of spots. In the course of some of the degradation experiments using sewage effluent as the medium, an increase in pH value was observed. Under these conditions the degradation of the alkyl phenol ethoxylate was much more rapid and complete than usual, and the resolved trace on the thin‐layer plate showed a predominance of ethoxy groups near the top of the chromatogram. In this series of experiments, as in those described in Part I, the foaming capacity during degradation could be closely correlated with the results obtained by using the thin‐layer chromatographic procedure.