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Method for recovering collagen and chromium salts from chromium-containing scrap leather residues

A technology of collagen and skin dregs, which is applied in the field of recovering collagen and chromium salts, can solve the problems of unsuitable preparation of fine chemicals for retanning fillers, high ash content of industrial collagen powder, high chromium content of collagen powder, etc., to achieve Realize the effect of effective separation, short treatment and recovery cycle, and less process

Active Publication Date: 2013-04-03
SICHUAN UNIV
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  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

Although the lime used in this method is cheap and the process is easy to control, on the one hand, the obtained industrial collagen powder has a high ash (calcium) content, which is not suitable for the preparation of high value-added fine chemicals such as retanning fillers. Because the recovered chromium precipitate contains a large amount of calcium ions and collagen hydrolyzate, it is not only unsuitable for tanning agent for tanning, but also becomes dangerous solid waste containing chromium that is difficult to handle, which is equivalent to solving a pollution while bringing other pollution
At the same time, because this method uses a large amount of calcium salt, it is easy to deposit on the inner wall of the pipeline and the container, causing pipeline blockage and reducing thermal efficiency.
[0005] In addition, Giuliano Guardini also reported (Guardini G. Process for recovery proteins and chromium from chrome-tanning waste[P]. US: 4483829, 1984-11-20.) A method using NaOH supplemented with MgO and Ca (OH) 2 The method of hydrolyzing chromium-containing waste skin residues to recover collagen peptides and chromium salts has 21 processes in the entire technical route. Not only is the operation too cumbersome, the treatment and recovery cycle is long, and the hydrolysis process is at pH ≥ 10.5 and the temperature is close to 100 ℃ Carried out under the conditions of [there are literature reports that Cr 3+ The optimal precipitation pH value is between 8.5 and 10.0 (Cao Yu, Yin Qing. Comparison of methods for treating hexavalent chromium wastewater [J]. Fujian Environment, 1999, (5): 35.), after exceeding 10.0, the resulting Cr(OH) 3 will become [Cr(OH) 4 ] - However, it is soluble in water], in addition, there is no chromium removal process in the follow-up process, which may lead to high chromium content (dry basis) in the recovered collagen powder, which limits its application
More importantly, due to the use of Ca(OH) in this method 2 , which may create problems similar to those caused by the lime hydrolysis method described above

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026]First add 200 parts of water, 3.5 parts of sodium hydroxide and 1 part of magnesium oxide to 100 parts of chromium-containing waste skin residue, then raise the temperature to 80°C, stir and cook for 5 hours, filter, concentrate the filtrate, recover collagen liquid or dry to obtain collagen Protein powder; after adding 8 parts of water to the filter residue, slowly add 10 parts of concentrated sulfuric acid while stirring, then raise the temperature to 90 ° C for 6 hours, and filter; slowly add 3 parts of sodium dichromate while stirring in the filtrate, and then Raise the temperature to 95°C and react for 4 hours, then slowly add 0.3 parts of glucose, keep warm and stir for 3 hours to make the resulting chrome slurry have a pH value of 2.8, and then obtain a chrome tanning solution or dry it to make a powdery chrome tanning agent.

[0027] The chromium content in the obtained collagen is 300mg / kg (as Cr 2 o 3 meter, dry basis).

Embodiment 2

[0029] First add 300 parts of water, 2 parts of potassium hydroxide, 1 part of sodium hydroxide, 1.5 parts of magnesium oxide and 0.1 part of sodium lauryl sulfate to 100 parts of chromium-containing waste skin residue, then raise the temperature to 95 °C and stir and cook for reaction 4.5 hours, filter, concentrate the filtrate, recover collagen liquid or dry to obtain collagen powder; add 8 parts of water to the filter residue, slowly add 10 parts of concentrated sulfuric acid and 2 parts of concentrated nitric acid while stirring, and then heat up to 90°C to react for 5 hour, filter; slowly add 2 parts of sodium dichromate to the filtrate while stirring, then raise the temperature to 85 ° C for 6 hours, then slowly add 0.3 parts of sucrose, keep warm and stir for 2 hours, so that the pH value of the obtained chromium slurry is 3.2 , that is, chrome tanning liquid or powdered chrome tanning agent by drying.

[0030] The chromium content in the obtained collagen is 210mg / kg (...

Embodiment 3

[0032] First add 80 parts of water, 2 parts of sodium hydroxide, 2.8 parts of magnesium oxide, 0.1 part of zinc oxide, 0.1 part of aluminum oxide and 0.2 part of Pingjia to 100 parts of chromium-containing waste skin residue, and then raise the temperature to Stir and cook at 200°C for 3 hours, filter, concentrate the filtrate, recover collagen liquid or dry to obtain collagen powder; add 8 parts of water to the filter residue, slowly add 10 parts of concentrated sulfuric acid while stirring, and then heat up to 90°C for reaction 6 hours, filter; slowly add 3 parts of potassium dichromate to the filtrate while stirring, then raise the temperature to 95°C for 4 hours, then slowly add 0.4 parts of brown sugar, keep warm and stir for 4 hours, so that the pH of the obtained chromium slurry is 3.0, that is, to obtain chrome tanning liquid or to make powdered chrome tanning agent through drying.

[0033] The chromium content in the obtained collagen is 235mg / kg (as Cr 2 o 3 meter,...

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Abstract

The invention discloses a method for recovering collagen and chromium salts from chromium-containing scrap leather residues, which comprises the following steps: carrying out alkaline hydrolysis on chromium-containing scrap leather residues with strong alkali assisted by metal oxide and surfactant, recovering collagen from the filtrate, hydrolyzing the filter residues with strong acid, and sequentially carry out redox reaction to obtain a chrome tanning solution or drying to obtain a powdery chrome tanning agent. The invention has the advantages of fewer steps, short period, high efficiency and low production cost, is simple to operate, and can implement effective separation of chromium and hydrolyzed collagen; the recovered industrial collagen has low chromium content and high added value, and thus, can be used as a raw material for producing other fine industrial chemicals; the recovered chromium salts are free of calcium salts, and thus, can be used as a tanning agent for leather tanning again; and the invention does not generate tailings or wastewater, thereby avoiding secondary pollution.

Description

technical field [0001] The invention belongs to the technical field of resource utilization of leather solid waste, and in particular relates to a method for recovering collagen and chromium salt from chromium-containing waste leather residue. Background technique [0002] A large amount of solid waste is inevitably generated during the tanning process. According to statistics, processing 1 ton of raw leather will produce 400-450 kilograms of solid waste, of which 30-40% are tanning waste leather residues (blocks), and my country produces about 1.4 million tons of such waste every year. More than 90% of these chromium-containing waste skins are collagen, and contain 2-4% Cr 2 o 3 . Collagen is not only an important protein resource, but also chromium resources are very scarce in my country, with an external dependence of 95% (Zhang Jian, Wang Denghong, Fu Ping. Chromium ore resource situation and prospecting direction in China[J]. Northwest China Geology, 2009, 42(3): 69-...

Claims

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Application Information

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IPC IPC(8): C14C3/32C07K14/78C07K1/12
CPCY02W30/50
Inventor 廖学品丁伟石碧周建飞张文华曹明蓉
Owner SICHUAN UNIV
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