Method of extracting gelatin and isolating chromium salts from wastes during treatment of tanned hides and skins

FIELD: leather industry.

SUBSTANCE: according to first embodiment of invention, method envisages acid hydrolysis by means of organic acids at temperature higher than room temperature and up to 100°C, extraction of crude gelatin after hydrolysis by way of filtration, and separation of low-grade gelatin and salts through desalting operation. Second embodiment is the same as above except that separation of gelatin and chromium salts is effected using dialysis. Further, ion exchangers are subjected to exhaustive regeneration to ensure complete recovery of chromium and isolation of chromium salts via diafiltration after dialysis with additional isolation and reuse of hydrolysis reagent.

EFFECT: increased yield of gelatin simultaneously with recovery of chromium salts under friendly environmental conditions.

34 cl, 4 dwg, 10 ex

 

The technical field to which the invention relates.

The present invention relates to the leather industry, in particular, relates to a method of extraction of gelatin and excretion of salts of chromium tanned hides and skins, with the regeneration of hydrolytic reagent.

The level of technology

The impact of the tanning of hides and skins on the environment very much, because this process generates large amounts of waste that are difficult to clean and use such highly polluting heavy metals as chromium. Thus, removal of waste leather industry poses a real problem. To date, we have adopted the following disposal methods: disposal at designated landfills, undifferentiated waste incineration without parsing and processing them, albeit in small quantities, in nitrogen fertilizer.

However, these methods do not solve the problem, but exacerbate it: in fact, wastes from the leather industry contain about 3% chromium, who, although he trivalent refers to heavy metals and has a tendency to accumulate. Thus, when such wastes are buried in landfills or used for the production of nitrogen fertilizers, they cause serious problems of soil contamination. Burning is not recommended because it leads to the formation of put the m oxidation at high temperatures - highly toxic hexavalent chromium and other by-products of combustion, and also in the gas phase, which pollute the environment and are toxic in varying degrees.

On the other hand, suggests ways to get rid of waste through the so-called "burning leather", resulting in nitrogen fertilizer, and most of the products after appropriate processing, can be of great economic importance from the point of view of reuse. It is well known that by-products of the leather industry can provide technical gelatin, as well as chromium, which with appropriate selection can be re-used in the tanning of hides and skins. Indeed, most of these products consist of substances on the basis of the collagen from which it is possible to obtain technical gelatin with a wide range of industrial applications. Except for the food and pharmaceutical industries, in which it is forbidden to use the products of the leather industry, technical gelatin is widely used, especially as an adhesive in many industries, for example in the manufacture of dyes and adhesives, matches and abrasive materials, textiles, paper and cardboard, as well as in the binding case.

Traditionally, the most widely used method of obtaining technical the CSOs gelatin by-products hides and skins, in practice, for example, in the treatment of 15% lime milk and wash under running water, followed by neutralization of lime sludge acid and gelatin extraction with water at a temperature of from 80 to 100°C. the Disadvantage of this method is the high consumption of water (up to 80 m3/hour) and receive technical gelatin of low quality. In addition, the manufacturing sector technical gelatin is faced now with difficulties, namely: lack of primary products, mainly because of the current trend towards localization of these industries in developing countries. However, technical gelatin, manufactured in developing countries, do not always meet the technical requirement on the part of consumers.

Instead, in the industrialized countries are rather well developed processing (shaving) tanned hides and skins, and it can cause other problems in connection with the disposal of waste (shaving) in the processing and release of by-products for processing (collagen gelatin and chromium). With this purpose, we developed several ways to get gelatin from collagen with low chromium content: mainly they are based on alkaline hydrolysis of liquid hot alkali extraction of gelatin, the translation of chromium in an insoluble form and subsequent stages of separation. In other ways alkaline guide is Aliso preceded by the extraction of chromium from waste in the processing of hides and skins with the help of acidic chemicals, able to bind trivalent chromium, and the separation of its precipitation. In other ways after hydrolysis followed by oxidation of trivalent chromium in the sediment to hexavalent chromium and its branch. These methods of obtaining gelatin with a low chromium content, based on the processing of alkaline reagents for hydrolysis of collagen and separation of chromium, consist of many stages and therefore it is less applicable in industry. Moreover, the alkaline processing provides obtaining gelatin poor quality and causes the formation of ammonia in the degradation of amide groups.

Therefore, the main task is to develop a way that is easy to apply on an industrial scale, which, starting with a piece of tanned hides and skins, containing Cr(III), will be able to provide for a small number of stages - getting high-quality collagen gelatin with high yield, as well as salts of chromium, which can be extracted and re-used in industrial production. Thus problems associated with waste will be minimized. The next task is to develop effective industrial method of obtaining without negative consequences for the environment, which, thus, provides for full utilization of by-products (waste water and hydrolytic reagents) and does not produce emissions zarazna the future of gas.

The invention

The applicant developed a highly effective method in accordance with the purposes of the present invention. The method consists of several stages, does not require alkaline processing and provides high-quality product (gelatin) with a good indicator of the mechanical resistance of the bloom, which therefore can be applied in industry and enables retrieval of the waste when processed (tanned hides and skins shaving) tanned hides and skins of chromium, which can be re-utilized in the leather industry. From the point of view of industry, the proposed method allows to isolate by-products (hydrolysis reagent and water), and from the point of view of ecology it is compatible with the requirements for environmental impact. Thus, a method consistent with the objectives of the present invention.

Thus, the object of the present invention is a process comprising acid hydrolysis of waste in the processing of tanned hides and skins, of chromium(III), at a pressure below atmospheric and at a relatively low temperature.

The method of obtaining gelatin and extraction of chromium salts that constitute the subject of the present invention includes at least the following stages:

a) acid hydrolysis of waste in the processing of raw hides and skins with the help of the organization is systematic acids at temperatures up to 100° C;

b) extraction of crude gelatin from solution obtained after hydrolysis by filtration, recycling of non-hydrolyzed products, if they are repeated hydrolysis;

c) separation of gelatin and salts of chromium by desalting ion-exchange resins.

The following objects of the present invention are: (i) recovery of acid reagent for hydrolysis and water for recycling and (ii) complete removal of chromium after desalting by selective regeneration of ion exchange resins.

Detailed disclosure of the invention

As shown in the flowsheet figure 1, the method of obtaining gelatin and extraction of salts of chromium from waste in the processing of tanned hides and skins constitute the subject of the present invention relates to a continuous process and consists of the following stages:

a) acid hydrolysis of waste in the processing of raw hides and skins with the help of organic acids at temperatures up to 100°C;

b) dilution water material obtained after the first hydrolysis;

c) extraction of crude gelatin from solution obtained after hydrolysis by mechanical filtration, recirculation of non-hydrolyzed products, if they are repeated hydrolysis;

(d) the Department of gelatin, salts of chromium and its clarification by desalting on ionoobmennihe;

e) concentrating, cooling and drying the obtained gelatin and water reuse;

f) concentrating the salts of chromium, obtained by standard regeneration of ion-exchange filters, by evaporation under vacuum to remove chromium salts and reuse of water.

As stated in the Abstract, the main production stages of this method are: acid hydrolysis of waste in the processing of tanned hides and skins in the aquatic environment; extraction of crude gelatin from solution by filtration of the hydrolysate; Department of gelatin by desalting ion-exchange resins with gelatin clarification and separation of the salts of chromium.

Detailed description of the production stages, these technological scheme 1, below.

Acid hydrolysis

Waste in the processing of raw hides and skins with an average moisture content of approximately 55%, which usually go to the dump, go to the plant laydown area, where they enter into the reaction tank equipped with a weighing device. Based on the number of downloads, with the help of the installed electronic control system calculates the number of input reactants (water and acid). To facilitate hydrolysis of this mass can be with constant stirring.

STA is in acids, as a rule, is from 10 to 80% relative to the weight of raw waste with an average moisture content of about 55%. Water is served at room temperature in the ratio from 4-fold to 10-fold relative to the weight of raw waste with an average moisture content of about 55%.

Hydrolytic reagents, preferably used for the acid hydrolysis, is an organic acid selected from the group consisting of monocarboxylic, polycarboxylic, hydroxy acids, such as formic, lactic, citric, tartaric acid, EDTA and equivalent acid, their salts and mixtures. Optional organic acid or mixtures thereof in the form of free acids or salts can be added together with inorganic acids such as sulfuric, and phosphoric acid equivalent, in an amount of 5 to 20% relative to the weight of waste during processing.

The mass in the tank is heated to a temperature up to 100°and length of stay at this temperature for about 0.5 to 30 hours. For example, mass can be heated by steam at a pressure of from 0.5 to 1 bar.

The temperature and duration of stay at the chosen temperature affect the hydrolysis of the protein material, and thus on the quality and quantity of the output derived gelatin. Higher temperature and long duration provides most of the output of gelatin, however, having the worst mechanical resistance to bloom. Therefore, the process parameters chosen based on the type of gelatin that you want to retrieve.

Continuous mixing using a paddle or anchor agitator improves the kinetics of the hydrolysis and increases the output.

Breeding untreated gelatin and extraction filtering

Upon completion of the acid hydrolysis of mass in the reaction tank, water is added in an amount necessary for the remaining stages. The hydrolyzed protein fraction, consisting of untreated gelatin, separated from the solid mass fraction consisting of non-hydrolyzed waste during processing, by filtering in the device for mechanical filtration, such as a centrifugal separator, drum filter, bag filter, filter press, rotary separator and equivalent. The solid mass is defined as unreacted solid residue. The solution of the hydrolyzed protein fraction containing the crude gelatin, is fed to the following stage, while the solid fraction is re hydrolysis. The cycle of hydrolysis/filtration of the solid residue of chromium can be repeated until the extraction of the maximum possible amount of gelatin. The quality of the gelatin does not depend on the number of cycles of extraction.

Department of gelatin on what salivarium

A solution of the crude gelatin, obtained by mechanical filtration, contains hydrolytic reagent, salts of chromium and has ash in amounts exceeding limits established in the technical specifications of the product for industrial applications.

A solution of the crude gelatin is subjected to desalting for simultaneous extraction of water, acid hydrolysis reagents and salts of chromium and reduce the ash content without noticeable loss of protein substances. Cleaning is carried out using ion exchange (cation, anion exchange or mixed) resins, selective to trivalent chromium. Filters with resin periodically regenerate for the extraction of captured salts of chromium. After the regeneration solution is directed to the concentration of the extracted salts of chromium.

Concentrating, drying and cooling

The resulting solution of gelatin is served in the multipurpose evaporator, and then subjected to cooling and drying, for example, in an air dryer.

The concentration of chromium salts

A solution of salts of chromium salt containing trivalent chromium and obtained during regeneration of the resin at the stage of demineralization concentrate by evaporation, preferably under vacuum, to give a concentrate, which manufacturers chromium salts are used for tanning, and water, which is used again.

To improve you the ode production and efficiency of the proposed method of producing gelatin and chromium salts may optionally include stages after acid hydrolysis (stage a) and filtration the crude gelatin (stage C) the following stage:

- Department of gelatin, salts of chromium and clarification by dialysis through a membrane;

- secretion of salts of chromium by diafiltration through the membrane with separation from the hydrolysis of the reagent from the first stage and re-using it.

These optional stage allow to obtain a gelatin of a higher quality and recover devoid of chromium hydrolytic reagent, which can be reused. Solutions of gelatin obtained with the first dialysis, can be used for desalting or concentrating and dried as described previously.

As shown in detail on technological scheme of figure 2, the process which is the subject of the present invention relates to a continuous process and includes the following stages:

a) acid hydrolysis of waste in the processing of raw hides and skins with the help of organic acids at temperatures up to 100°C;

b) dilution water material obtained after the first hydrolysis;

c) extraction of crude gelatin from solution obtained after hydrolysis by mechanical filtration, with non-hydrolyzed products, if they are repeated hydrolysis;

d) isolation of gelatin by dialysis through a selective membrane for clarification and separation from the salts of chromium;

e) desalting of gelatin by filtration XP is modirzadeh balance through the resin;

f) concentrating, cooling and drying the obtained gelatin and water reuse;

g) isolation of salts of chromium by diafiltration through the membrane is selective to the salts of chromium, with separation from the hydrolysis of the reagent from the first stage;

h) the concentration of hydrolytic reagent through a selective membrane with its recovery and reuse water;

i) the concentration of salts of chromium, obtained by diafiltration and regeneration of ion-exchange filters, by evaporation under vacuum to remove chromium salts and reuse of water.

The main production stages of this method are: acid hydrolysis of waste in the processing of tanned hides and skins; extraction of crude gelatin from solution by filtration of the hydrolysate; Department of gelatin from chromium and clarification by dialysis, diafiltration solution containing salts of chromium.

Optional stages that are included in the technological scheme of figure 2, described in detail below. Main stages described above.

Department of gelatin by dialysis

A solution of the crude gelatin, obtained by mechanical filtration, optionally may be subjected to dialysis before desalting. Adding water to individual portions dialysis allows you to simultaneously remove acidic hydrolysis reagents and salts of chromium is from aqueous solution and to reduce the ash content without noticeable loss of protein. For dialysis applied porous membrane with a molecular sieve from 1000 to 30,000 daltons, which inhibit protein molecules approximately 50,000 daltons, and ignore such charged low-molecular substances, such as salts of chromium and acid. The acidic solution after dialysis is collected and directed to the selection of hydrolytic reagent, and salts of chromium.

Department of salts of chromium by diafiltration

Containing chromium salt and hydrolysis reagent solutions collected after dialysis, put diafiltration through selective membranes for the separation of salts of chromium from hydrolytic reagent. If diafiltration as a filter applied porous membrane with a molecular sieve of 200 to 500 daltons, holding up the two - and trivalent ions and miss molecules with low charge type hydrolytic reagent. After appropriate concentration gather both factions. Get a hydrolytic reagent with output up to 70%.

The concentration of hydrolytic reagent

Hydrolysis reagent is isolated and used again for hydrolysis after concentration, which is carried out using membranes for reverse osmosis or vacuum evaporators. The obtained water re-use.

The concentration of chromium salts

Solutions of chromium salts containing trivalent chromium and obtained diafiltration and wash smo is at the stage of demineralization, concentrated by evaporation under vacuum, as described previously. Get the concentrate, which manufacturers chromium salts are used for tanning. Water re-use.

To improve the efficiency of selection, from the point of view of industry, primarily chromium, and then hydrolysing reagent proposed method after desalting optionally includes a special kind of regeneration of the ion exchanger, designed for:

- reduce consumption of reagents used for regeneration of ion-exchange filters;

- more concentrated solution of salts of chromium, which do not require further concentration, decreases the volume of the concentrate solution and conserve energy.

As shown in the flowsheet figure 3, the proposed method is a continuous process and includes the following stages:

a) acid hydrolysis of waste in the processing of raw hides and skins with the help of organic acids at temperatures up to 100°C;

b) dilution water material obtained after the first hydrolysis;

c) extraction of crude gelatin from solution obtained after hydrolysis by mechanical filtration, with non-hydrolyzed products, if they are repeated hydrolysis;

d) desalination of gelatin by filtering chromiferous mod is and through the resin;

e) selective regeneration of ion-exchange filters;

f) concentrating, cooling and drying the obtained gelatin and water reuse.

Optional stages that are included in the technological scheme of figure 3, described in detail below. Main stages described above.

Selective regeneration of ion-exchange filters

When ion-exchange filters lose their ability to retain salt, they must be regenerated with the help of adequately diluted acidic or alkaline regenerant solutions and subsequent washing. Adopted our methodology is to allocate three regeneration fractions, referred to as head, middle and tail, where:

- head fraction depleted regenerating means and chrome salts;

- the average fraction depleted regenerating means, but enriched with salts of chromium and forms a concentrated fraction;

- tail fraction enriched with regenerating means and depleted in chromium salts.

Head and tail fractions are combined and after adding fresh regenerant used to fill a regenerant in the following cycles of regeneration.

The middle fraction consists of a solution containing from 2 to 4% of chromium, and does not require additional concentration.

The consumption of regenerating means (as alkaline, the acid) is reduced by approximately 50%, and the volume of flushing water, which still contains salts of chromium and therefore should be concentrated, is reduced by about 70%.

A continuous method of obtaining gelatin and complete extraction of salts of chromium, together with hydrolytic reagent and water, which consists of all the stages described above, also includes the following stages, as shown in the flowsheet figure 4:

a) acid hydrolysis of waste in the processing of raw hides and skins with the help of organic acids at temperatures up to 100°C;

b) dilution water material obtained after the first hydrolysis;

c) extraction of crude gelatin from solution obtained after hydrolysis by mechanical filtration, with non-hydrolyzed products, if they are repeated hydrolysis;

d) isolation of gelatin by dialysis through a selective membrane for clarification and separation from the salts of chromium;

e) isolation of chromium by diafiltration through the membrane is selective to the salts of chromium, with separation from the hydrolysis of the reagent from the first stage;

f) the concentration of hydrolytic reagent through a selective membrane with its recovery and reuse water;

g) desalting of gelatin by filtration chromium residue through the resin;

h) concentration, drying and cooling is dedicated gelatin;

i) from irately regeneration of ion-exchange filters;

(j) the concentration of salts of chromium, obtained by diafiltration and regeneration of ion-exchange filters, by evaporation under vacuum to remove chromium salts and reuse of water.

Information confirming the possibility of carrying out the invention

The following examples relating to the receipt of gelatin and extraction of chromium salts and hydrolysis of the reagent on the basis of the proposed method, provides for the disclosure of the present invention but not to limit.

Example 1

Acid hydrolysis, filtration and desalting

In the reactor 100 l contributed waste to the treatment (10 kg)containing 56% moisture and approximately 2% of trivalent chromium, along with a 20-30% solution of citric acid (6 kg) and distilled water (34 kg). Waste during processing was stirred at room temperature for several hours and was stirred with an anchor stirrer. The reaction mass was heated up to 20°under stirring with an anchor stirrer and a weak transmission of air for better mixing. Hydrolysis was launched steam in the jacket of the reactor. After 2 hours of heating at 80-90°hydrolysis of waste when processing has completed. The resulting product was diluted with distilled water in the ratio 1:1 by weight, getting solution (90 l) at a temperature of 60°containing 9% of glue.

Before Phi is trevanian, which was conducted using the built-in felt bag filter 100 μm instead of centrifuges, first conducted preliminary filtration through bag filter 400 μm, and optionally diluted with 50°With in a separate reactor.

After filtration through a filter of 100 μm was obtained a solution of the hydrolysate and about 3-4% of unreacted residue (in terms of dry weight).

The efficiency of hydrolysis was 83% by weight of the raw waste.

A solution of gelatin obtained by acid hydrolysis and filtration were subjected to desalting, passing through two columns filled with weak anionoobmennika and strong cation-exchanger, respectively (150 ml). In particular, gelatin (380 ml) was diluted with distilled water (1:1) and was passed through two columns filled with anion exchange resin A100 and cation exchange resin S (150 ml), washed and heated to 80°With water. This operation was performed using a diluted gelatin at 50°and passing 5 times the column volume. The resulting solution was concentrated under vacuum.

After desalting received a solution of gelatin with a dry weight of 16%; beats. weight to 1.034 at 40°and viscosity 115,4 mPas at 40°C.

After drying obtained gelatin with indicator bloom 421; viscosity 127 mPas; the content of Cr(III) to 0.15% by weight; a moisture content of 17%; ash content at 560°: 1,1%; lemon is the first acid was not determined.

Example 2

Acid hydrolysis, filtration and desalting

In a laboratory flask made waste treatment (50 g)containing 56% moisture and about 2% of trivalent chromium, together with 9-10% solution of lactic acid (400 ml). After stirring the mass for several hours at room temperature with stirring with an anchor stirrer was subjected to hydrolysis (96%) at about 90°C for 30 min, and then diluted with distilled water (1:1) at room temperature and filtered through a gauze filter type drymad. The solution was passed through a column Packed with a mixture ion exchanger and heated water up to 80°C. the Solution was concentrated and dried, obtaining gelatin with indicator bloom 370; the content of Cr(III) 0.2% by weight; ash content of 1.5% and a moisture content of 10%.

Example 3

Dialysis, concentration and drying of gelatin

The gelatin solution obtained after filtration in Example 1, was collected in a container and provided the temperature is about 50°C. the Solution was subjected to dialysis in the setting ultrafiltration using a membrane with a limit exceptions 6,000 for the Department of gelatin from the hydrolysis reagent and chromium. After the volume of dialysate (gelatin) was reduced by 50%, individual portions was added osmosis purified water at 50°With the ratio of 1:2 for the best dialysis citric acid and chromium. Under the volume once more decreased. After dialysis received:

- gelatin containing 0.2% citric acid and 0.01% chromium;

- dialysis solution containing 0.2% of citric acid and 0.005% chromium.

Obtained in the dialysis solution of gelatin was concentrated, receiving semi-solid gelatin containing 12.5% of dry matter, as well as distilled water, which was recuperable.

Semi-solid gelatin was utverjdali, crushed and dried. When this was received gelatin with output relative hydrolyzed waste when processing 30%; indicator bloom 324; a moisture content of 3%; viscosity by Ostwald: 177 mPas at 12.5 percent; the content of citric acid 5%, Cr(III) 0.2% by weight; ash content at 560°From 2.1%.

Example 4

Diafiltrate citric acid

Dialysis solution obtained by dialysis of gelatin in Example 3 was concentrated in the plant for nanofiltration using a membrane with a limit exceptions 200-300, receiving the penetrating phase, devoid of chrome, but containing a small amount of citric acid. This number is small, because there is periodic process, and a continuous process in a stationary mode, you can get a greater amount of citric acid. After diafiltration received: penetrating phase (permeate), devoid of chromium and containing 0,02% citric acid; held-phase (retentate)containing 1.4% of citric acid and 0,039% chromium.

P is obtained by diafiltration penetrating phase was concentrated in a reverse osmosis system, receiving the following:

held-phase (retentate)containing 0.3% of citric acid;

purified reverse osmosis water containing 30 ppm (mg/l) residual citric acid.

Example 5

Acid hydrolysis, filtration and dialysis

In a laboratory flask made waste treatment (50 g)containing 56% moisture and about 2% of trivalent chromium, together with 4-5% solution of lactic acid (800 ml). This mass was subjected to hydrolysis (99%) at about 50°C for 30 hours, with stirring anchor stirrer, was diluted with distilled water (1:1) at room temperature and filtered through a gauze filter type drymad. The filtered solution deliberately by ultrafiltration in dialysis cell against distilled water (3 l) at 50°C. the Solution was concentrated and dried, obtaining gelatin with indicator bloom 370; the content of Cr(III) 0.4 percent by weight; ash content 2%; moisture 8%.

Example 6

Selective regeneration of the resin in the columns

After desalting of the sample gelatin as in Example 1, a column of anion exchange resin was regenerated with a solution consisting of 30% NaOH and heated to 60°With distilled water in the ratio 1:5. The column was washed with distilled water, first at low speed and then at high speed. Eluate collected so as to obtain the average fraction (concentrated eluate), enriched trejbal ntim chrome.

Head and tail fractions containing aqueous eluate and the eluate depleted in Cr, respectively, were United motherly liquid, which can be reused for regeneration of the anion at the subsequent stages: head + tail fraction is 40% of the volume; the Cr content Is 0.04%; NaOH 0.7 percent.

"Average" fraction concentrate, which can be used in the production of chromium salts: the average fraction of 10% of the volume; the content of Cr: 0,2%; NaOH: 0,3%.

Example 7

Acid hydrolysis, filtration, dialysis, desalting, diafiltrate and selective regeneration

In the reactor 200 l contributed waste to the treatment (10 kg)containing 56% moisture and approximately 2% of trivalent chromium, along with a 20-30% solution of citric acid (6 kg) and distilled water (34 kg). Waste during processing of stirring at room temperature for several hours and was stirred with an anchor stirrer. The reaction mass was heated up to 20°under stirring with an anchor stirrer and a weak transmission of air for better mixing. Hydrolysis was launched steam in the jacket of the reactor. After 2 hours of heating at 80-90°hydrolysis of waste when processing has completed. The resulting product was diluted with distilled water in the ratio 1:1 by weight, getting solution (90 l) at a temperature of 60°containing 9% of glue.

Before filtration is a Finance, which was conducted using the built-in felt bag filter 100 μm and not centrifuge, first conducted preliminary filtration through bag filter 400 μm, and optionally diluted with 50°With in a separate reactor.

After filtration through a filter of 100 μm was obtained a solution of the hydrolysate and about 3-4% of unreacted residue (in terms of dry weight).

The efficiency of hydrolysis was 83% of the weight of raw waste during processing. The gelatin solution obtained after filtration was collected in a container and brought up to 50°C. the Solution was subjected to dialysis in the setting ultrafiltration using a membrane with a limit exceptions 6,000 for the Department of gelatin from the hydrolysis reagent and chromium. After the volume of dialysate (gelatin) was reduced by approximately 50%, individual portions was added osmosis purified water at 50°With the ratio of 1:2 to enhance dialysis citric acid and chromium. At the end of the volume is further decreased. After dialysis received:

gelatin containing 0.2% citric acid and 0.01% chromium;

dialysis solution containing 0.2% of citric acid and 0.005% chromium.

Part of the solution of gelatin, obtained by dialysis, was subjected to desalting, passing through two columns, respectively, filled with a weak anionoobmennika and strong cation-exchanger (10 ml). In particular, gelatin (400 ml) was diluted with distilled water (1:1) and was passed through two columns filled with anion exchange resin A100 and cation exchange resin S (150 ml), washed and heated to 80°With water. This operation was performed using a diluted gelatin at 50°and passing 5 times the column volume. The resulting solution was concentrated under vacuum.

After drying the solution obtained gelatin with indicator bloom 436; viscosity 153 mPas; the content of Cr(III) to 0.12% by weight; a moisture content of 17%; ash content at 560°S: 1,5%; citric acid was not determined.

Dialysis solution obtained by dialysis of gelatin, concentrated in the plant for nanofiltration using a membrane with a limit exceptions 200-300, receiving the penetrating phase, devoid of chrome, but containing a small amount of citric acid. This number is small, because there is periodic process, and a continuous process in a stationary mode, you can get a greater amount of citric acid. After diafiltration received:

- penetration phase (permeate), devoid of chromium and containing 0,02% citric acid;

- held-phase (retentate)containing 1.4% of citric acid and 0,039% chromium.

Obtained diafiltration penetrating phase was concentrated in a reverse osmosis system, receiving the following:

- held-phase (retentate), with whom containing a series of 0.3% of citric acid;

- osmosis purified water containing 30 ppm (mg/l) residual citric acid.

After desalting of the sample of gelatin column with anion exchange resin was regenerated with a solution consisting of 30% NaOH and heated to 60°With distilled water in the ratio 1:5. The column was washed with distilled water, first at low speed and then at high speed. Eluate collected so as to obtain the average fraction (concentrated eluate), enriched trivalent chromium.

Head and tail fractions containing aqueous eluate and the eluate depleted in Cr, respectively, were United motherly liquid, which can be reused for regeneration of the anion at the subsequent stages: head + tail fraction is 40% of the volume; the Cr content Is 0.04%; NaOH 0.7 percent.

"Average" fraction concentrate, which can be used in the production of chromium salts: the average fraction of 10% of the volume; a content of Cr Of 0.2%NaOH and 0.3%.

Example 8

Acid hydrolysis using lactic and formic acid, filtration and dialysis

In a laboratory flask were introduced 50 g of waste in the processing of leather, containing 56% moisture and about 1.2% trivalent chromium, 350 ml of 9-10% solution of formic acid and 50 ml of 9% solution of lactic acid. After stirring for 1 hour at room temperature, with stirring with an anchor stirrer, this mass was subjected to hydro is studied by 80% at about 90° C for 30 minutes, After hydrolysis, this mass was diluted with distilled water (1:1) at room temperature and filtered through a gauze filter type drymad, then filtered solution deliberately by ultrafiltration in dialysis cell against distilled water (about 2 l) at 50°finally, the solution was passed through a column Packed with a mixture ion exchanger, pre-heated to 80°With water. After concentration and drying of the solution was obtained gelatin with indicator bloom 360; the content of Cr(III) 0.2% by weight; ash content of 1.55%; moisture content of 10%.

Example 9

Acid hydrolysis using citric and sulfuric acid, filtration and desalting

In a laboratory flask were introduced 50 g of waste in the processing of leather, containing 41% moisture and about 2% of trivalent chromium, 550 ml of 2.5% solution of sulfuric acid and 50 ml of a 6.5% solution of citric acid. This mass was subjected to hydrolysis at 85% at about 90°C for 90 min, with stirring anchor stirrer. After hydrolysis, this mass was diluted with distilled water 1:1 at room temperature and filtered through a gauze filter type drymad, then the filtered solution was diluted again 1:1 and twice absoluely at 50°C, passing through two columns filled with a weak anion exchange resin and a strong cation exchange resin (150 ml) and pre-heated to 80�B0; Water.

After concentration and drying of the solution was obtained gelatin with indicator bloom 336; content of Cr(III) to 0.15% by weight; ash content of 1.1%; moisture content of 10%.

Example 10

Hydrolysis using disodium salt of EDTA and sulfuric acid, filtration and desalting

In a laboratory flask were introduced 50 g of waste during processing, containing 41% moisture and about 16% of trivalent chromium, 350 ml of 2.5% solution of sulfuric acid and 350 ml of 2.5% solution of disodium salt of EDTA. This mass was subjected to hydrolysis in 80% about 90°C for 60 min, stirring with an anchor stirrer. After hydrolysis, this mass was diluted with distilled water 1:1 at room temperature and filtered through a gauze filter type drymad, then the filtered solution was diluted again 1:1 and twice absoluely at 50°C, passing through two columns filled with a weak anion exchange resin and a strong cation exchange resin (150 ml) and pre-heated to 80°With water.

After concentration and drying of the solution was obtained gelatin with indicator bloom 320; Cr(III): 0,17% by weight; ash content of 1.2%; a moisture content of 13%.

The proposed method fully meets the above objectives of the invention: development of industrial methods, allowing to extract from the waste in the processing of tanned hides and skins by-products (collagen gelatin and chrome), which is possible to recover and reuse in industrial production, thereby minimizing the problem of disposal of waste; obtaining quality products with great economic value for subsequent use in industry; develop a method that does not have harmful consequences for the environment, which, thus, provides for full utilization of by-products (hydrolysis reagents, regenerating means and wastewater) and does not produce polluting emissions.

It should be noted that provided by the invention and the necessary process of acid hydrolysis proceeds very quickly and gives the hydrolysate with a yield of about 80% relative to the raw waste in the processing stages without alkali treatment. Finally, this hydrolysis provides obtaining gelatin satisfactory quality, which in any case takes measure of the resistance of the bloom is not less than 300, and is not accompanied by the formation of gaseous waste. Non-hydrolyzed residue waste in the processing of tanned hides and skins may be directed to further hydrolysis. This operation can be repeated until a complete or exhaustive hydrolysis of the source material without compromising the quality of gelatin. The following cycles of hydrolysis, in fact, provide technical gelatin with similar technical characteristics.

The hydrolysate containing gelatin, hydrolysis is eagent and salts of chromium, subjected to successive operations of the division with three main ingredients: gelatin, regenerated hydrolytic reagent, and salts of chromium in solution.

All products undergo further processing and selection, in particular gelatin goes on sale; chrome salts used on the production of chromium salts for tanning, therefore, they have industrial application; hydrolytic reagent, regenerating means for ion exchangers and the water is continually recirculated.

It is very important that this method does not apply polluting reagents and do not form liquid or gaseous emissions, therefore, it is environmentally friendly. Only drying of gelatin causes some loss of water. A different, but no less important feature of this method in relation to the impact on the environment unlike ways of getting protein hydrolyzed by alkaline hydrolysis is that when degradation aminogroup not formed ammonia.

Various variations and modifications can be made without departing from the spirit and within the new concept of the present invention. Thus, the proposed method may be subject to modification and improvement of specialists in this field in accordance with the technical knowledge and experience in this field, as well as with the normal evolution of the industry.

1. The method of obtaining gelatin and extraction of salts of chromium from waste in the processing of tanned hides and skins, including at least the following stages:

acid hydrolysis using organic acids at temperatures above room temperature and up to 100°C;

extraction of the crude gelatin after hydrolysis by filtration;

the division of technical gelatin and salts of chromium by desalting.

2. The method according to claim 1, in which at the stage of acid hydrolysis

apply organic acid which is selected from the group consisting of monocarboxylic, polycarboxylic, hydroxy acids, their salts and mixtures;

acids are used in a ratio of from 10 to 80% relative to the weight of waste during processing with an average moisture content of about 55%;

water is used in the ratio from 4-fold to 10-fold relative to the weight of waste with an average moisture content of about 55%;

the mass is heated to a temperature of from 50 to 100°C.

3. The method according to claim 1, in which organic acids are used in combination with inorganic acids at a ratio of inorganic acids of from 5 to 20% by weight of waste with an average moisture content of about 55%.

4. The method according to claim 1, in which organic acids are formic, lactic, citric, EDTA, tartaric acid, their salts and/or see the sea.

5. The method according to claim 3, in which the inorganic acid is selected from the group consisting of sulfuric and phosphoric acids.

6. The method according to claim 2, in which the duration of stay of the mass under conditions of elevated temperature is from 0.5 to 30 p.m.

7. The method according to claim 1, in which extraction of crude gelatin occurs by filtration mass after dilution.

8. The method according to claim 7, in which the filtering for the extraction of crude gelatin occurs through mechanical filtration units, selected from a number of centrifugal separators, drum filters, bag filters, filter presses, rotary separators.

9. The method according to claim 1, wherein the acid hydrolysis and filtration is repeated until complete extraction of gelatin.

10. The method according to claim 1, in which separation of gelatin and salts of chromium occurs by desalting in one or several stages on the ion exchange resin selective to trivalent chromium.

11. The method according to claim 1, further comprising the stage of:

separation of gelatin and chromium salts by dialysis after filtration;

secretion of salts of chromium by diafiltration after dialysis with additional extraction and reuse of hydrolytic reagent.

12. The method according to claim 11, in which the dialysis is conducted through the porous membrane with a molecular sieve from 1000 to 30,000 daltons.

13. The method according to claim 11, in which diafiltrate is conducted through the porous membrane with a molecular sieve of 200 to 500 daltons.

14. The method according to claim 1, additionally including

selective regeneration of ion exchangers for the complete removal of chromium.

15. The method according to 14, in which the selective regeneration of ion exchangers is using acidic and alkaline regenerant solutions and subsequent cleaning, you get a head fraction depleted in regenerating means and salts of chromium, average fraction depleted in regenerating means, but enriched with salts of chromium and forming a concentrated phase extraction of chromium, and a tail fraction enriched with regenerating means and depleted in chromium salts.

16. The method according to item 15, in which the head fraction depleted in regenerating means and salts of chromium, and a tail fraction enriched with regenerating means and depleted in chromium salts are pooled to obtain a regenerating means for reuse in subsequent regeneration of ion exchangers.

17. The method according to any one of claims 1 to 16, in which the solutions of gelatin after desalting collect and concentrate.

18. The method according to any of § § 11-16, in which the gelatin solutions after dialysis collect and concentrate.

19. The method according to any one of claims 1 to 16, in which the solutions of salts of chromium on the Le desalting ion exchangers collect and concentrate.

20. The method according to any of § § 11-16, in which the solutions of salts of chromium after diafiltration exchangers collect and concentrate.

21. The method according to any of p-16, in which the solutions of salts of chromium after the election regeneration of ion exchangers collect and concentrate.

22. The method according to any one of claims 1 to 16, in which the phase containing the hydrolysis reagent after desalting, collect and use again.

23. The method according to any of § § 11-16, in which the phase containing the hydrolysis reagent after diafiltration, collect and use again.

24. The method according to 17, in which the water collected in the concentration of gelatin used again.

25. The method according to p in which water collected at concentration of gelatin used again.

26. The method according to claim 19, in which the water collected in the concentration of salts of chromium, re-use.

27. The method according to claim 20, in which the water collected in the concentration of salts of chromium, re-use.

28. The method according to item 21, in which the water collected in the concentration of salts of chromium, re-use.

29. The method of obtaining gelatin and extraction of salts of chromium from waste in the processing of tanned hides and skins, which includes stages:

acid hydrolysis using organic acids at temperatures above room temperature and up to 100°C;

extraction of the crude Gelati is by filtration and after acid hydrolysis;

separation of gelatin and chromium salts by dialysis after filtration;

the division of technical gelatin and salts of chromium by desalting after dialysis;

selective regeneration of ion exchangers for the complete removal of chromium;

secretion of salts of chromium by diafiltration after dialysis with additional extraction and reuse of hydrolytic reagent.

30. The method according to clause 29, in which the solutions of gelatin after desalting and/or dialysis collect and concentrate.

31. The method according to clause 29, in which the solutions of salts of chromium after demineralization, and/or diafiltration and/or selective regeneration of ion exchangers collect and concentrate.

32. The method according to clause 29, wherein the phase containing the hydrolysis reagent after desalting and/or diafiltration, collect and use again.

33. The method according to item 30, in which the water collected in the concentration of gelatin used again.

34. The method according to p, in which the water collected in the concentration of salts of chromium, re-use.



 

Same patents:
The invention relates to methods for the regeneration of spent solutions containing toxic chromium compounds, for example, leather and fur industries

The invention relates to the leather industry and can be used in the processing of irreversible collagen chrome tanning waste, mainly of chrome shavings, to obtain an additional source of protein raw materials in the production of gelatin, mezdrovogo glue and protein hydrolysate

The invention relates to light industry and can be used in cosmetics, the production of adhesives and other industries
The invention relates to food industry, in particular, to the production of gelatin adhesives, paints and varnishes based on it, pharmaceuticals, photo paper

The invention relates to methods for processing collagen refuse to produce collagen solutions used in veterinary medicine, medicine, pharmaceutical and cosmetic industries

The invention relates to the food industry

The invention relates to the food industry

FIELD: skin industry, in particular reprocessing of offal waste.

SUBSTANCE: offal waste is ground and treated with enzyme preparation in amount of 0.1-0.5 % based on waste mass at 60-75°C for 2-4 hours. As enzyme preparation protolichetherm obtained from Bacillus Licheniformis is used. Method of present invention is useful in production of adhesive, gelatin, and feed supplement.

EFFECT: protein hydrolyzate of improved quality.

2 tbl, 1 ex

The invention relates to the leather industry, in particular to a technology for production of proteins from tannery waste chrome tanning

FIELD: skin industry, in particular reprocessing of offal waste.

SUBSTANCE: offal waste is ground and treated with enzyme preparation in amount of 0.1-0.5 % based on waste mass at 60-75°C for 2-4 hours. As enzyme preparation protolichetherm obtained from Bacillus Licheniformis is used. Method of present invention is useful in production of adhesive, gelatin, and feed supplement.

EFFECT: protein hydrolyzate of improved quality.

2 tbl, 1 ex

FIELD: leather industry.

SUBSTANCE: according to first embodiment of invention, method envisages acid hydrolysis by means of organic acids at temperature higher than room temperature and up to 100°C, extraction of crude gelatin after hydrolysis by way of filtration, and separation of low-grade gelatin and salts through desalting operation. Second embodiment is the same as above except that separation of gelatin and chromium salts is effected using dialysis. Further, ion exchangers are subjected to exhaustive regeneration to ensure complete recovery of chromium and isolation of chromium salts via diafiltration after dialysis with additional isolation and reuse of hydrolysis reagent.

EFFECT: increased yield of gelatin simultaneously with recovery of chromium salts under friendly environmental conditions.

34 cl, 4 dwg, 10 ex

FIELD: chemistry.

SUBSTANCE: method involves washing collagen-containing material, crushing, boiling, separating the broth, filtering, evaporating and drying. After washing, the material is rinsed with an anolyte of an electrochemically activated solution with pH 2.5-6. Collagen is extracted by enzymatic hydrolysis of the material. The hydrolysis process is carried out with a catholyte of an electrochemically activated solution with pH 7.5-8.5 for 2-2.5 hours until achieving degree of hydrolysis on solubility of the material of 45.5-48.5 wt % of the material. The gelatine broth is evaporated to content of dry substances of 15-20% and then dried in foamed state with foam layer thickness of 2-4 mm with relative air humidity of 50-60% for 3-4 hours.

EFFECT: cutting duration of the process of extracting collagen and drying the broth, obtaining an end product with high protein content, low content of moisture and sols, and improved organoleptic properties.

3 tbl, 3 ex

FIELD: leather industry.

SUBSTANCE: according to first embodiment of invention, method envisages acid hydrolysis by means of organic acids at temperature higher than room temperature and up to 100°C, extraction of crude gelatin after hydrolysis by way of filtration, and separation of low-grade gelatin and salts through desalting operation. Second embodiment is the same as above except that separation of gelatin and chromium salts is effected using dialysis. Further, ion exchangers are subjected to exhaustive regeneration to ensure complete recovery of chromium and isolation of chromium salts via diafiltration after dialysis with additional isolation and reuse of hydrolysis reagent.

EFFECT: increased yield of gelatin simultaneously with recovery of chromium salts under friendly environmental conditions.

34 cl, 4 dwg, 10 ex

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