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Ultrasonic wave chromium removing process for tannery containing chrome leather scraps oxidation

A chrome leather scrap and ultrasonic technology, applied in the field of ultrasonic oxidative dechromization, can solve problems such as incomplete oxidative dechromization, and achieve the effects of less damage, high purity and large molecular weight

Inactive Publication Date: 2003-12-31
SICHUAN UNIV
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AI Technical Summary

Problems solved by technology

The present inventors have found that applying ultrasonic waves in the process of oxidative dechromation produces oxygen free radicals due to the cavitation effect of ultrasonic waves, which has a synergistic effect on oxidative dechromation, can significantly increase the speed of oxidative dechromation, and overcomes the problem of oxidative dechromation at the same time. The defect of incompleteness makes the dechroming rate of chromium-containing waste leather shavings reach more than 99%

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0015] 1. Mix 100kg of chrome-containing leather shavings, H 2 o 2 Content 30% 5kg, H 2 The amount of O is 100kg and added to the reactor with a thermometer and agitator together, adjust the pH = 8.5 to 11 with CaO, start the agitator, insert an ultrasonic probe at a temperature of 20°C, and apply ultrasonic waves with a power of 200w and a frequency of 20KHz , each action time is 0.5 hours, filter with filter cloth, wash the filter residue with acid and alkali alternately once, then adjust pH=8.5~11 with CaO, add the same amount of H 2 o 2 and H 2 O, apply ultrasonic waves, the action time is all operated according to the previous process conditions, so repeat 8 times, respectively measure the dechrome rate as shown in Table 1.

[0016] 2. Mix 100kg of chrome-containing leather shavings, H 2 o 2 Content 30% 5kg, H 2 Add O100kg together to an ultrasonic cleaner with a thermometer and agitator at a frequency of 40KHz and a power of 50W, adjust the pH to 8.5 to 11 with Ca...

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Abstract

The ultrasonic oxidation and chromium eliminating process for chromium containing leather leftover features that chromium containing leather leftover in 100 weight portions, 30 % concentration H2O2 solution in 3-15 weight portions and water in 50-400 weight portions are mixed in a reacting container while being pH regulated to 8.5-11 with alkali, and ultrasonic wave treated at 10-40 deg.c with ultrasonic wave of power 50-1200 w and frequency 20-400 KHz for 0.5-3.0 hr each time. After filtering, the filtered sludge is washed with acid and alkali before being returned to the said ultrasonic wave treatment. The said treatment process is repeated for several times until reaching the chromium eliminating requirement.

Description

1. Technical field [0001] The invention relates to an ultrasonic oxidation dechroming method for chromium-containing waste leather shavings in tanning, and belongs to the field of recycling chromium-containing leather shavings waste and eliminating environmental pollution in the tanning industry. 2. Background technology [0002] Waste chromium leather shavings generally contain about 90% protein (calculated on a dry basis), Cr 2 o 3 3 to 6%, the key to the recycling of waste chromium leather scraps is to make the Cr in waste chromium leather scraps 3+ Removal, conventional dechroming methods include acid method, alkali method, acid-base alternating method and enzymatic method. The acid method is to use hydrochloric acid, sulfuric acid, oxalic acid or citric acid to treat chromium-containing waste leather scraps to hydrolyze the collagen, and then adjust the pH to separate the chromium from the collagen hydrolyzate in the form of chromium hydroxide precipitation, but the a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C14C3/32
CPCY02W30/50
Inventor 石碧孙丹红
Owner SICHUAN UNIV
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