Biological behavior of some soap‐based detergents

The biodegradability of tallow soap, three soap‐based detergent formulations and their component lime soap dispersing agents—sodium methyl α‐sulfotallowate, sulfated N‐(2‐hydroxypropyl) tallowamide, and sodium N‐methyl N‐(2‐sulfoethyl) tallowamide—was determined under aerobic and microaerophilic conditions. Both sewage and river water microorganisms were used as the sources of inoculum. The course of biodegradation was followed by loss of carbon and methylene blue active substance, and by increase in turbidity and surface tension. Carbon analysis for soap in solutions containing Ca ++ and Mg ++ , which would precipitate soap, was performed by an improved technique using the disodium salt of ethylenediamine tetraacetic acid. Invariably a decrease in carbon content was accompanied by an increase in turbidity and surface tension. Also, loss in methylene blue active substance was concurrent with an increase in turbidity and surface tension of the degrading solutions of the detergent. Soap cannot be determined as methylene blue active substance because of the low pH of the test. Soap and the built soap formulations degraded under aerobic and microaerophilic conditions. Preliminary toxicity data upon mammals and fish indicated that the soap‐based detergents are as safe as conventional commercial detergents.