CN1144836C

CN1144836C - Process for extracting protein from leather leftover

Info

Publication number: CN1144836C
Application number: CNB01106725XA
Authority: CN
Inventors: 张小燕; 杨德玉; 高全昌; 刘华强
Original assignee: Northwest University
Current assignee: Northwest University
Priority date: 2001-01-17
Filing date: 2001-01-17
Publication date: 2004-04-07
Anticipated expiration: 2021-01-17
Also published as: CN1313352A

Abstract

The present invention relates to a new extraction method for proteins from leather leftovers. The present invention is characterized in that the contained proteins are extracted by the technology of pretreatment, hydrolysis, decolorization, concentration and drying in sequence, the harmful substances of pigments, etc. in a waste liquid of the pretreatment are removed by the adsorption of activated carbon, and C as a harmful element is converted into chemical products of Cr(OH)SO4 by the methods of acidolysis and neutralization. Animal proteins extracted by the present invention, which are rich in 18 kinds of amino acids have the advantages of rich nutrient and easy absorption, and are excellent additives for animal fodder. The obtained byproducts of Cr(OH)SO4 can be used for tanning leather; the residual waste slag in the reaction can be used as high-grade organic fertilizer. The present invention can effectively and comprehensively utilize the leather leftovers coated with oil and color, and the simplified technology of the present invention is also suitable for the utilization of common leather leftovers. In addition, the present invention has the advantages of high efficiency, less investment, low cost, etc., and well solves the problems of comprehensive utilization and pollution treatment by changing waste into valuables.

Description

Method for extracting protein from leather leftovers

The present invention belongs to the field of organic chemical treatment technology, and is especially comprehensive utilization technology of tanning leftover.

In the leather industry and leather product industrial production, a large amount of leather leftovers such as fur, raw hide, corner blocks, blue vitriol skin, chrome leather scraps and the like are generated, the leftovers are rich in 70-80% of colloid protein, and the colloid protein in the leftovers is extracted by adopting a long-time high-pressure and high-temperature chemical treatment method for the undried and undyed leather leftovers in the prior art. However, no effective utilization method is available for oiled and colored chrome leather scraps at present, because the chrome leather scraps contain 2-4% of harmful substances: mineral oil, colored dyes, trivalent chromium and the like, wherein the mineral oil and the organic dyes can harm the growth of animals and plants, and the trivalent chromium is a toxic carcinogen. The chrome leather scraps are difficult to utilize and only need to be abandoned, thus causing great pollution to the environment.

The invention aims to find a method which has simple process, low cost and high efficiency, can fully extract useful substances in chrome leather scraps and solve the problem of environmental pollution caused by harmful substances.

The invention is realized by the following steps:

the method takes chrome leather scraps as raw materials and sequentially comprises the following process steps of extracting protein: 1. pretreatment, 2, hydrolysis, 3, decolorization, 4, concentration, 5 and drying.

In the pretreatment, NaOH is used as deoiling and decoloring agent, and Ca (OH) is used₂The weight ratio of the chrome leather scraps to the deoiling and decoloring agent to the deconning agent is 100: 2-5: 5-6. The temperature of the pretreatment is 90-100 ℃, and the time is 0.5-1 hour. Through pretreatment, organic dye and saponified mineral oil in the chrome leather scraps enter waste liquid.

And (3) adsorbing the waste liquid generated by pretreatment by using activated carbon, wherein the using amount of the activated carbon is 50-70% of the weight of the chrome leather scraps. When the adsorption is saturated, the carbon dioxide is generated by burning away the carbon dioxide; the rest liquid is clean water, and can be recycled or discharged.

And adding an extracting agent, a chromium removing agent CaO and water into the pretreated chrome leather scraps to perform hydrolysis reaction. The extractant is composed of NaOH and Ca (OH)₂Mixing the components in the ratio of NaOH to Ca (OH)₂The weight ratio of the chromium leather scraps to the chrome leather scraps is 1: 3-5: the extraction agent, the chromium removing agent and the water are 100: 2-3: 2-4: 700-900. Then heating at 80-100 ℃ for 1.0-1.5 hours. At this time, collagen in the chrome leather shavings was hydrolyzed into soluble mixed amino acids. Thenfiltering and separating into filtrate and filter residue.

Adding hydrogen peroxide into the filtrate for carrying out a decoloration reaction, wherein the adding amount of the hydrogen peroxide is 3-5% of the total amount of the filtrate, further concentrating to 16-18 Baume degrees, and then carrying out spray drying to obtain a substance with a nutritive value, namely animal protein.

The trivalent chromium in the filter residue is Cr (OH)₃In the form of precipitate, dilute H is added first to eliminate the pollution problem₂SO₄The dissolution pH is 1-2. Then filtering to separate the dissolved solution from the waste residue. Neutralizing the separated solution with alkali, wherein the amount of the alkali is 1-2% of the chrome leather scraps, and enabling Cr in the chrome leather scraps to be in a state of being dissolved in the solution³⁺Conversion to Cr (OH) SO₄. The chemical reaction of the process is as follows:

then the obtained product is concentrated, crystallized, filtered and dried to generate Cr (OH) SO₄Is a useful chemical product and is also a chemical raw material used in tanning leather.

The waste residue left after dissolution is a mixture of fibrous tissues, soil, residual animal protein and the like, and can be used as fertilizer.

The chrome leather scraps colored by the oil are taken as raw materials, and are fully extracted by scientific chemical treatment meansThe collagen is modified into water-soluble animal protein which is easy to absorb, the protein is easy to absorb and rich in nutrition, contains 18 amino acids, wherein the content of crude protein ismore than or equal to 80 percent, can be used as a feed additive for animals such as chicken, duck, fish, pig, cattle, sheep and the like, and can also be used as important chemical raw materials such as a wool nursing agent, a high-grade nutritional cosmetic and the like. Some harmful substances contained in the chrome leather scraps are converted into useful chemical raw materials after chemical treatment, and some harmful substances are combusted to generate CO₂. The invention is not only suitable for oiling,The comprehensive utilization of the coloring chrome leather scraps can treat the leather leftovers which are not oiled and colored by adopting the simplified process technology, and compared with the prior treatment technology, the treatment is not required to be carried out under the conditions of long time and high pressure. The invention has the advantages of simple process, convenient operation, high efficiency, low cost and the like, and realizes comprehensive utilization and pollution control.

Two embodiments of the invention are described below with reference to the accompanying drawings:

FIG. 1; the general process flow diagram of the invention.

FIG. 2 is a drawing: the acid treatment process flow chart of the hydrolysis waste residue.

Example 1: into a 1000ml beaker, 50 g of chrome leather shavings, NaHOH 2.5 g, Ca (OH)₂2.5 g, heated at 90 ℃ for 1 hour. The generated wastewater is absorbed by 2.5 g of activated carbon and then burnt; washed chrome shavings, along with 0.25 grams NaOH, 0.75 grams Ca (OH)₂2 g of CaO, 350 g of water were heated together at 80 ℃ for 1.5 hours, and then filtered. Adding 33% hydrogen peroxide into the filtrate, wherein the addition amount of the hydrogen peroxide is 3% of the filtrate amount, then concentrating to 16 Baume degree, finally drying and crushing to obtain the product, namely the animal protein. The residue obtained by hydrolysis is treated with 30% H₂SO₄Dissolving until PH is 2, and then filtering and separating the dissolved solution and the waste residue. The filtered solution is neutralized by 5 g of NaOH, and then is concentrated, crystallized, filtered and dried to obtain the useful chemical product Cr (OH) SO₄. And the residue left after acidolysisCan be used as organic fertilizer.

Example 2: into a 1000ml beaker, 50 g of chrome leather scraps, 1 g of NaOH, Ca (OH)₂3 g, heated at 100 ℃ for 0.5 hour; the resulting waste water was adsorbed with 35 g of activated carbon and then burned. Washed chrome shavings, along with 0.25 grams NaOH and 1.25 grams Ca (OH)₂1 g CaO and 450 g water were heated together at 100 ℃ for 0.5 hour, and then filtered. Adding 33 percent (weight percentage) of hydrogen peroxide into the filtrate, wherein the adding amount of the hydrogen peroxide is 5 percent of the total amount of the filtrate, then concentrating the mixture to 18 Baume degrees, and finally drying and crushing the mixture to obtain the product, namely the animal protein. The residue from the hydrolysis is treated with 30% H₂SO₄Dissolving, and then filtering and separating a dissolved solution and waste residues; the dissolved solution is neutralized by 6 g of NaOH, and finally, the solution is concentrated, crystallized and dried to form a useful chemical product Cr (OH) SO₄. And the waste residue can be used as organic fertilizer.

Claims

1. The method for extracting the protein from the leather leftovers is characterized in that leather chromium scraps are taken as raw materials, and the method sequentially comprises the following process steps of extracting the protein: 1. pretreating, 2, hydrolyzing, 3, decoloring, 4, concentrating, 5 and drying; the deoiling and decoloring agent for pretreatment is NaOH, and the tanning agent is Ca (OH)₂The harmful substances in the pretreated waste liquid are adsorbed by adopting activated carbon, and the pretreated chrome leather scraps are extracted by using an extractant NaOH + Ca (OH)₂Carrying out hydrolysis reaction on CaO and water serving as a chromium removing agent, and using dilute H to filter residues generated after hydrolysis₂SO₄Adding alkali for neutralization after dissolution to generate Cr (OH) SO₄Adding hydrogen peroxide into the hydrolyzed filtrate for decolorization, concentrating and drying.

2. The method according to claim 1, characterized in that the weight ratio of the deoiling and decolorizing agents, the decoanning agents and the chrome leather shavings added during the pretreatment is, chrome leather shavings: NaOH Ca (OH)₂＝100∶2～5∶5～6。

3. The method of claim 1, wherein two components of the extractantThe weight ratio of the parts is NaOH to Ca (OH)₂＝1∶3～5。

4. The method according to claim 1 or 2, wherein the temperature of the pretreatment is 90 to 100 ℃ and the time is 0.5 to 1 hour.

5. The method of claim 1, wherein the hydrolysis is carried out using NaOH + Ca (OH) as an extractant₂The weight ratio of the water to the chrome leather scraps is 100: 2-3: 2-4: 700-900.

6. The method as claimed in claim 1, wherein the concentration of the hydrogen peroxide used in the decoloring reaction of the hydrolyzed filtrate is 33% (by weight), and the amount of the hydrogen peroxide added is 3 to 5% of the filtrate.