Sorption of Nonionic Surfactants on Sediment Materials

• Published in: Environmental science & technology 1997-06, Vol.31 (6), p.1735-1741
• Main Authors: Brownawell, Bruce J, Chen, Hua, Zhang, Wanjia, Westall, John C
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Chemistry; environmental degradation; Exact sciences and technology; Pollution; Sediments; Soil and sediments pollution; soil chemistry; soil physics; soil science; Surfactants; waste management; Water
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es960692k

The distribution of a series of nonionic surfactants between sediments and water was studied as a function of surfactant structure, ionic strength, pH value, Ca2+ concentration in solution, sediment composition, and concentration of suspended solids. The surfactants were monotridecyl ethers of poly(ethylene glycol), also known as alcohol ethoxylates, A n E x = CH3(CH2) n - 1(OCH2CH2) x OH), with n = 13 and x = 3, 6, and 9. Isotherms were nonlinear, with the degree of nonlinearity and the extent of sorption increasing with the number of oxyethylene (-OCH2CH2-) groups. Freundlich isotherms represented the data well. The pH and ionic strength of the solution had a small effect on sorption, but the effect increased with the number of oxyethylene groups. These observations suggest that the oxyethylene chain is specifically adsorbed, presumably through a hydrogen-bond mechanism. Addition of Ca2+ did not affect the distribution of AEs. The distribution ratios of the AEs did not correlate well with the fraction organic carbon of the sediments; the amount of swelling clay in the sediment may affect distribution ratios. The concentration of solids had no effect on the extent of sorption.