Method for measuring alkalinity of surfactant based on potentiometric titration method

Abstract

The invention discloses a method for determining alkalinity of a surfactant based on potentiometric titration, and relates to the technical field of surfactant performance determination. The method comprises the following steps: weighing 3-5g of a sample, adding the sample into 100mL of water, placing the water on a high-precision photo-thermal potential analyzer, adding a magnetic rotor, and uniformly stirring; selecting dynamic titration as a titration method, wherein the maximum void volume is 0.4 mL, and the minimum void volume is 0.02 mL; and using a pH composite electrode, after the electrode and a feed tube are immersed into the liquid level, using the prepared 0.1 mol / L hydrochloric acid titration solution for titration to the end point, and the titration volume is read. The pH composite electrode is adopted, the titration end point is judged through potential jump, an indicator does not need to be added into a titration system, the titration end point is judged by detecting a jump point of a titration curve through the potential electrode, and judgment of the titration end point is more accurate; and the problem that the titration end point of a dark or lightproof sample is inaccurately judged by using a photometric electrode is solved.

Description

technical field [0001] The invention belongs to the technical field of measuring the performance of surfactants, in particular to a method for measuring the alkalinity of surfactants based on a potentiometric titration method. Background technique [0002] Surfactant is a general term for substances that can significantly change the surface state of a solution system. As one of the commonly used additives in the petrochemical industry, surfactants are widely used in the fields of oilfield three mining and cosmetic products. An important performance indicator that will affect the performance of surfactant products, such as the irritation of cosmetics to the skin, the selection of co-surfactants, etc., and affect the subsequent wastewater treatment process. [0003] The determination of alkalinity in surfactants is currently mainly based on the national standard "Titration Method for the Determination of Alkalinity of Surfactants" (GB / T 7378-2012), using manual titration and j...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a method for measuring the alkalinity of surfactants based on potentiometric titration, using pH composite electrodes, judging the titration end point through potential jumps, no need to add indicators in the titration system, and solving dark or opaque samples The problem of inaccurate judgment of titration end point

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