For the surfactants, non-ionic surfactants are most suitable, and fatty acid esters such as glycerine fatty acid esters, sorbitan fatty acid esters and sucrose fatty acid esters may be used.
The characteristics of structures and composition for sorption carboxylic esters and polyoxyethylene sorbitan carboxylic esters of typical non _ ionic surfactants are indicated by NMR, MS and IR.