Thesis Details

Thesis Title: Foam fractionation of textile dye wastes for pollution abatement
Thesis Author: Alan Tippy
Abstract: Pollution is becoming an ever-increasing and threatening problem in today's society. The Institute, as is the case with numerous other private and governmental agencies, is very interested in the alleviation of pollution, especially in those areas in which pollution directly affects the textile industry. The general public is not primarily concerned with the technical aspects of pollution, but rather with the more noticeable problems of odor, color, and taste. Little concrete information, however, was available on the inexpensive removal of color-causing constituents from surface waters. Foam fractionation may be simply defined as a unit process which removes pollutants from liquid by means of a froth or foam. The fractionating apparatus, as utilized in this experimental investigation, was adopted from an earlier design. Certain modifications were made, however, in an effort to control as many experimental variables as possible. Basically, the influent liquor was pumped into the fractionator from an overhead mixing barrel at controlled flows designed to insure proper liquor dwell times. Foam was produced by air which entered the system at controlled flow and pressure through a flat and circular carborundum diffuser. The effluent foam was collected ina drum and collapsed with a prescribed amount of anti foam emulsion. Disperse dyes of both the azo and anthraquinone classes were investigated. The dyes were Foron Navy S-2GL and Eastman Fast Blue B-GLF, respectively. Optical density measurements were used as a means to determine the enrichment or depletion of dye in the foam and the time required for the fractionation system to stabilize. The surfactants employed in this thesis investigation were Triton X-100, Sandopan DTC, and Bionol RO-50. These typified the nonionic, anionic, and cationic surfactant classes,respectively. The foam fractionation experiments showed that the chemical structure of the dye had no apparent effect on the amount of dye fractionated, as the mechanism by which dye was removed was purely physical and depended primarily on the suspending power of the surfactant for the dye. Contrary to that which was expected, the dyes were concentrated in the effluent liquor and not in the foam. The performance of the foam fractionation system was best when high air flows, high surfactant concentrations, and long liquor dwells were employed. The effluent from the fractionator was divided into two fractions, effluent as liquor and effluent as foam. The per cent dye in the effluent liquor under the above conditions averaged approximately one-and-one-half per cent enrichment. Foam fractionation appears to be a feasible treatment process for some types of textile mill wastes. Except for cationics, the ionic class of surfactant did not significantly affect the amount of color removed. Bionol RO-50, the cationic surfactant caused coagulation and precipitation with both dyes because they apparently contained an anionic dispersant. The amount of influent throughput of the system as a percentage of the amount of effluent collected as foam was dependent on the surfactant concentration, the air flow rate, and the duration of liquor dwell. Longer liquor dwell times and higher air flow rates were conducive to optimum performance of the fractionation system.