Infrared Analysis of Aqueous Textile Processing Solutions Using a ZnSe Horizontal ATR Cell

Although water-based solutions are frequently encountered in textile processes, ana lyzing aqueous solutions is considered to be a difficult task with infrared spectroscopy because of the high absorptivity of the water spectrum and the general incompatibility of water with common infrared cell materials. In this study, textile processing solutions, including indigo dye solutions and polyester caustification wastewater, are analyzed by an infrared method using a trough-type ZnSe horizontal ATR cell. IR spectra of the indigo dye solution feature two intense sulfite and sulfate peaks occurring at 937 and 1100 cm-1, respectively. These peaks provide an easy way to determine the optimum vatting condi tions as well as to estimate the degree of ageing of indigo stock and dyebath solutions. The ethylene glycol component in polyester caustification wastewater is also conveniently measured quantitatively or semiquantitatively by IR analysis without laborious sample preparation.