Method for measuring polyvinyl alcohol content in water

Abstract

The invention discloses a method for measuring polyvinyl alcohol content in the water. An excessive sulfuric acid is added under neutral heating condition (60-90 DEG C.) to remove starch having interference to the measurement by hydrolysis, and the excessive acid reacts with the polyvinyl alcohol in the sample to generate an ester in the mean time. In presence of boracic acid, the polyvinyl alcohol and the ester generated by reaction of the polyvinyl alcohol and the sulfuric acid can both react with a boracic acid - iodine - potassium iodide solution to produce a stable blue-green complex compound, and an absorbency is measured by a spectrophotometer at a point of a special wavelength of 645nm. A standard work curve is drawn according to the linear relation between the absorbency and the concentration of the reactor, thus the concentration of the sample can be known by checking the drawn standard curve after the sample measurement. The invention controls measurement error within the range of 5%, and the measurement result is stable and accurate, which makes the invention a feasible method for measuring polyvinyl alcohol concentration in the printing waste water.

Description

technical field [0001] The invention relates to a method for analyzing and measuring chemical substances, in particular to a method for determining the content of polyvinyl alcohol in water by using a spectrophotometer. Background technique [0002] Textile printing and dyeing wastewater contains dyes, sizing agents, additives, oil agents, acids and bases, fiber impurities, sand substances, inorganic salts, etc., and has the characteristics of large water volume, strong impact load, high content of organic pollutants, partial alkalinity, and water quality changes. Large and other characteristics, is one of the difficult industrial wastewater. For a long time, printing and dyeing wastewater has been recognized as one of the serious water pollution. At present, in order to meet the requirements of the market, there are endless varieties of textile printing and dyeing products, and the addition of many dyes, auxiliaries, and surfactants with complex structures has resulted in ...

AI Technical Summary

Problems solved by technology

The inventor adopts this assay method to carry out verification through a series of basic experiments (experimental process, see Annex 1) and finds that there is a large error in this assay method, and the measurement result reproducibility is relatively poor

The inventor thinks that in the actual use of PVA size, it contains certain starch, CMC size, polyacrylic acid size, etc., which are more likely to interfere with the PVA measurement, and wherein starch is an unavoidable interference in the actual PVA measurement. , the above measurement method fails to eliminate the relevant interference, thus bringing inevitable measurement errors, resulting in inaccurate measurement results