Abstract:

Adsorbable organic halogens (AOX) are often introduced or produced in textile and dyeing processes, such as the chlorination shrink proof process of wool, the bleaching process by sodium hypochlorite and chlorite, the dry-cleaning process by chlorinated solvent, etc. However, part of AOX is difficult to biodegrade and is a persistent bioaccumulative toxic substance with high fat solubility. To promote clean production of textiles and to protect the health of consumers, a conventional method for the detection of AOX in textiles must be established urgently. In this study, a new method was developed for the determination of AOX in textiles by ultrasonic extraction-high temperature combustion absorption-ion chromatography (IC). In this method, AOX in textiles were extracted by ultrasonic extraction at room temperature with ultra-pure water as solvent. Activated carbon was added to the extraction solution for oscillatory adsorption and removal of inorganic halides with acidic sodium nitrate solution. The AOX adsorbed on activated carbon were cracked, burned, and gasified by the oxidative combustion method with a programmed heating mode. The product hydrogen halide gas entered the absorption solution with the carrier gas, followed by separation and determination by IC with external standard method of quantification. During the experiment, the pretreatment conditions were optimized, including the extraction time of AOX, the amount of activated carbon, the combustion gas and its flow rate, the temperature program for high-temperature oxidation combustion, the absorption method, and the absorption solution. The instrument conditions of ion chromatography, including the chromatographic column, column temperature, eluent, and its flow rate, were also optimized. The results showed that the method was linear in the range of 0.02-10 mg/L for the standard solutions of fluorine, chlorine, bromine, and iodine ions, and the correlation coefficients (R²) were greater than 0.999. The limits of quantification of the method for AOX were 0.10-0.50 mg/kg. The negative textile samples of cotton, wool, and polyester were used as the sample matrix, and typical organic halogens were selected for standard addition and recovery. At low, medium, and high spiked levels, the average recoveries of AOX in cotton, wool, and polyester fiber were 82.3%-98.7%. The corresponding relative standard deviations (RSDs, n=7) were 2.0%-5.7%, indicating that the method had good recovery and precision. This method was used to determine actual textile samples, and AOX at different contents were detected in blue coated polyester fabric and black modal fabric with good repeatability. The established method improved the recoveries of AOX converted into inorganic halogens via oscillating adsorption of activated carbon, high-temperature oxidation combustion with a programmed heating mode, and secondary absorption using a porous absorption bottle. Meanwhile, the separation and detection of halogen ions was successfully conducted using the ion chromatography instrument with good selectivity and high sensitivity, without any interference of impurity ions. The method is simple, accurate, and reliable, and fully meets the limit requirements of domestic and foreign regulations and textile standards; the method is also suitable for the detection and analysis of AOX in textiles.

Key words: ion chromatography (IC), ultrasonic extraction, high temperature combustion absorption, adsorbable organic halogens (AOX), textiles