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Method for testing isoelectric point of leather

A test method and isoelectric point technology, which are applied in measurement devices, material analysis by electromagnetic means, instruments, etc., can solve the problems of cumbersome operation, inaccurate measurement results, and incompatibility, and achieve accurate test results and operation. easy effect

Active Publication Date: 2015-11-18
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a fast and accurate isoelectric point test method suitable for various leather solids, to overcome the existing test methods or the inability to measure the isoelectric point of leather solids, or the measurement results are inaccurate and have no Disadvantages of universality and cumbersome operation

Method used

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  • Method for testing isoelectric point of leather
  • Method for testing isoelectric point of leather
  • Method for testing isoelectric point of leather

Examples

Experimental program
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Effect test

Embodiment 1

[0028] (1) After washing the bare hide after the pickling process, dry it at 20°C until the moisture content of the leather is 5wt%, then cut and crush it into leather samples to be tested with a particle size of 0.5-0.6 mm;

[0029] (2) 20g of the leather sample to be tested is mixed with 300ml of water to form a leather suspension, and the pH of the suspension is adjusted to 3.3-9 with hydrochloric acid solution or sodium hydroxide solution;

[0030] (3) accurately measure the pH of the above-mentioned leather suspension with a pH meter;

[0031] (4) Put the above leather suspension in Mütek TM Under the SZP-10Zeta potentiometer, then vacuum pumped into the measuring chamber equipped with a screen and two ring electrodes to form a leather sample plunger, the pumping time is 60s, and then the vacuum degree is constantly changed between -0.2~-0.4bar , generating pulsed liquid flow, stripping counterions, this stage lasts 30s, streaming potential, conductivity and pressure dif...

Embodiment 2

[0034] (1) After washing the leather after the vegetable tanning process, dry it at 40°C until the moisture content of the leather is 10wt%, then cut and crush it into a leather sample to be tested with a particle size of 0.7-0.8mm;

[0035] (2) Mix 15g of the leather sample to be tested with 400ml of water to form a leather suspension, and adjust the pH of the suspension to 2.5-4.5 with hydrochloric acid solution or sodium hydroxide solution;

[0036] (3) accurately measure the pH of the above-mentioned leather suspension with a pH meter;

[0037] (4) Put the above leather suspension in Mütek TMUnder the SZP-10Zeta potentiometer, then vacuum pumped into the measurement chamber equipped with a screen and two ring electrodes to form a leather sample plunger, the suction time is 80s, and then the vacuum degree is constantly changed between -0.2~-0.4bar , generate pulsed liquid flow, stripping counterions, this stage lasts 44s, streaming potential, conductivity and pressure diff...

Embodiment 3

[0040] (1) After washing the leather after the chrome tanning process, dry it at 70°C until the moisture content of the leather is 10wt%, then cut and crush it into leather samples to be tested with a particle size of 2-2.5mm;

[0041] (2) Mix 10 g of the leather sample to be tested with 400 ml of water to form a leather suspension, and adjust the pH of the suspension to 6-10 with hydrochloric acid solution or sodium hydroxide solution;

[0042] (3) accurately measure the pH of the above-mentioned leather suspension with a pH meter;

[0043] (4) Put the above leather suspension in Mütek TM Under the SZP-6Zeta potentiometer, then vacuum pumped into the measurement chamber equipped with a screen and two ring electrodes to form a leather sample plunger, the suction time is 80s, and then the vacuum degree is constantly changed between -0.2~-0.4bar , generate pulsed liquid flow, stripping counterions, this stage lasts 44s, streaming potential, conductivity and pressure difference ...

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Abstract

The invention discloses a method for testing an isoelectric point of leather. The method comprises the following steps: a leather suspension is prepared from a to-be-tested leather sample, and the pH of the suspension is regulated; the leather suspension is placed under a Zeta potential instrument, the streaming potential, the conductivity and the pressure difference are determined, and the Zeta potential of the leather sample is calculated with a Helmholtz-Smoluchowski formula; a curve showing the relation between the pH and the Zeta potential is drawn according to the tested pH of the leather suspension and the tested Zeta potential of the leather sample, the pH when the Zeta potential is equal to zero is found out and set as the isoelectric point of the leather. The method for testing the isoelectric point of the leather can determine the isoelectric point of solid leather, and compared with various conventional testing methods only capable of determining the isoelectric point of a leather simulant such as a collagen or gelatin solution, the method can reflect the isoelectric points and the amphoteric charge characteristics of leather materials more truly and more accurately and provides theory basis for establishment of a leather processing technology.

Description

technical field [0001] The invention relates to a method for testing the chemical properties of leather, in particular to a method for testing the isoelectric point of leather. Background technique [0002] Leather is a natural polymer material woven from collagen fibers, and its main component—collagen is a typical amphoteric polyelectrolyte. The side chain carboxyl groups of glutamic acid and aspartic acid residues contained in skin collagen can release protons, and the side chain basic groups of residues such as lysine, hydroxylysine and arginine can accept protons, so that Leather has an amphoteric charge and an isoelectric point (the value is the pH of the ampholyte solution when the zeta potential is equal to zero or no electrokinetic phenomenon occurs). In addition, in the process of leather processing, on the one hand, chemical reactions such as combination and cross-linking of skin collagen with various chemicals will consume part of the side chain acid / basic group...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/00
Inventor 王亚楠石碧曾运航周建飞张文华廖学品曹明蓉
Owner SICHUAN UNIV