CN107814849B - Method for removing sodium chloride in tapioca starch polysaccharide iron complex liquid - Google Patents

Abstract

A method for removing sodium chloride in cassava starch polysaccharide iron compound liquid comprises the following steps: adding cassava starch and water into a reaction kettle, heating and adjusting the pH value, adding a hydrogen peroxide solution to degrade the cassava starch to obtain an oligosaccharide solution with the weight-average molecular weight of 3K-27 KDa, and then adding a ferric trichloride solution and alkali to perform a complex reaction to obtain a cassava starch polysaccharide iron liquid; b, carrying out ultrafiltration on the cassava starch polysaccharide iron liquid prepared in the step A, intercepting a small molecular cassava starch polysaccharide iron compound with the molecular weight of 2.5K-200KDa, removing part of sodium chloride and C, carrying out nanofiltration on the permeate liquid obtained in the step B, intercepting a small molecular cassava starch polysaccharide iron compound with the molecular weight of 200Da by using a nanofiltration membrane, removing the sodium chloride and D, combining the intercepted liquids obtained in the step B and the step C, carrying out spray drying to obtain a solid cassava starch polysaccharide iron compound, and directly discharging the nanofiltration permeate liquid. The method has the advantages of simple process, energy conservation, environmental protection, mild condition and easy continuous production; the concentration of sodium chloride in the cassava starch polysaccharide iron compound liquid can be reduced; the recovery rate of the cassava starch polysaccharide-iron compound is more than 99%, and the removal rate of sodium chloride is more than 98%.

Description

Method for removing sodium chloride in tapioca starch polysaccharide iron complex liquid

technical field

The invention relates to a method for removing sodium chloride in tapioca starch polysaccharide iron complex liquid, in particular to a method for removing sodium chloride in tapioca starch polysaccharide iron complex liquid by applying ultrafiltration and nanofiltration membrane combination technology sodium chloride and concentration.

Background technique

As an iron supplement, polysaccharide iron complex has the characteristics of good stability and little irritation to the stomach and intestines. The polysaccharide itself has various biological activities and is easy to be absorbed and utilized by humans and animals. Certain iron polysaccharides such as iron dextran have been widely used clinically. The polysaccharide iron complex is composed of two parts: sugar group and glycosyl iron. The sugar group can be dextran (dextran), tapioca starch sugar, chitosan, sucrose, plant polysaccharide, etc. Plant polysaccharide iron complexes have become a hot spot in the pharmaceutical industry because of their unique health-care functions. The tapioca starch polysaccharide iron complexes using tapioca starch degradation products, tapioca starch polysaccharides as ligands, have a large source of raw materials and low prices, and the preparation process is simple. , the effect of iron supplementation on animals is remarkable and has attracted the attention of the breeding industry. The polysaccharide iron complex is actually a general term for a polymer polysaccharide iron complex with a wide molecular weight distribution. It is prepared by the reaction of polysaccharide and ferric chloride. A large amount of sodium chloride (10~20%wt), if it is directly concentrated and dried to prepare dry polysaccharide iron products, because it contains a large amount of sodium chloride and does not meet the requirements for use, it is especially not suitable for the configuration of injections, and sodium chloride is easy to use. Moisture absorption makes the product easy to agglomerate, which is not conducive to preservation. Therefore, the sodium chloride in the polysaccharide iron complex must be removed.

In the traditional process, alcohols such as ethanol can be used as a precipitant to separate the sodium chloride in the polysaccharide-iron complex. The operation process of this method is relatively complicated. Ethanol is a flammable and explosive substance, and there are potential safety hazards in production. The recovery of ethanol requires a large amount of consumption. steam, the production cost is higher.

Chinese patent CN101585887 discloses a method for desalting and concentrating an aqueous solution of iron dextran complex by applying nanofiltration technology. The method first uses a microfiltration membrane for pretreatment and then uses a nanofiltration membrane for concentration. The method for removing sodium chloride and concentrating the ferric dextran reaction completion liquid stock solution within the scope, for the tapioca starch polysaccharide obtained by the reaction of tapioca starch polysaccharide obtained by hydrogen oxide degradation and ferric trichloride reaction with tapioca starch as raw material The removal of sodium chloride and concentration of the complex reaction completion liquid are not suitable for two main reasons: 1. The molecular weight distribution of tapioca starch polysaccharides degraded by hydrogen peroxide is very wide. According to different degradation processes, the molecular weight distribution ranges from several thousand to 2. The pore size of the microfiltration membrane is generally 0.1 to 1 μm, and it can only retain particles with a particle size larger than 0.1 μm in the solution, and the impurities brought by the tapioca starch polysaccharide iron complex molecules and tapioca starch raw materials can only be retained. Such as vegetable protein can not be intercepted. When these microfiltration membrane-treated tapioca starch polysaccharide iron complex reaction completion liquids are nanofiltered to remove salt by nanofiltration membranes with low permeation flux, the osmotic pressure is very large, and impurities in the solution are also easy to cause nanofiltration membranes. Blockage, resulting in high pressure of nanofiltration operation, difficult to carry out nanofiltration operation smoothly, and low nanofiltration efficiency. Chinese patent CN103224571B discloses a method for desalting and concentrating an aqueous solution of a crude polysaccharide iron complex by using an ultrafiltration membrane separation technology with a molecular weight cut-off of 5K~150KDa. This method is also not suitable for the removal of sodium chloride and concentration of the cassava starch polysaccharide-iron complex reaction completion liquid obtained by the reaction of tapioca starch polysaccharide obtained by hydrogen oxide degradation and ferric trichloride using tapioca starch as raw material, because the The molecular weight of the polysaccharide iron intercepted by the method is greater than 5KDa, while the tapioca starch polysaccharide obtained by acid degradation with tapioca starch as the raw material and the ferric trichloride reacted to obtain the tapioca starch polysaccharide iron complex with a wider molecular weight distribution range, according to different preparations Process, the distribution of the weight-average molecular weight of the obtained polysaccharide iron is generally between 3K-27KDa, or even wider, and the molecular weight of some tapioca starch polysaccharide-iron complexes is less than 5KDa. If this method is used for desalination and concentration, there will be two unfavorable effects. Consequences: 1. Tapioca starch polysaccharide iron complexes with molecular weight less than 5KDa will pass through the ultrafiltration membrane, resulting in a decrease in the yield of tapioca starch polysaccharide iron complexes. The polysaccharide iron recovery rate of the patented method is only greater than 95%; The processed tapioca starch polysaccharide iron complex contains a high carbon source, which leads to a high content of COD in the permeate, which cannot be directly discharged. It must be further processed to make the COD of the solution meet the discharge standard before discharge. Therefore, there is no ideal process for removing sodium chloride and concentrating the reaction completion liquid of tapioca starch polysaccharide-iron complex synthesized by the reaction of tapioca starch polysaccharide obtained by hydrogen oxide degradation and iron reaction with tapioca starch as raw material. The combined technology of ultrafiltration and nanofiltration proposed in the present invention can better solve the above problems. For the tapioca starch polysaccharide obtained by acid degradation with tapioca starch as raw material, the tapioca starch polysaccharide iron compound synthesized by the reaction of ferric chloride The reaction completion liquid has good sodium chloride removal and concentration effect, simple and safe operation process, energy saving and environmental protection, mild conditions, easy continuous production, the recovery rate of tapioca starch polysaccharide iron complex is greater than 99%, and the removal rate of sodium chloride is greater than 98%. , the nanofiltration permeate can be directly discharged, and there is no similar report at home and abroad.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for removing sodium chloride and concentrating tapioca starch polysaccharide iron complex liquid by applying ultrafiltration and nanofiltration membrane combination technology, and this method can reduce the completion liquid of tapioca starch polysaccharide iron complex synthesis reaction At the same time, the concentration of cassava starch polysaccharide iron complex is increased, and the COD concentration of the nanofiltration permeate is low, which can be directly discharged. The invention has the advantages of simple and safe operation process, energy saving and environmental protection, mild conditions, easy continuous production, high recovery rate of tapioca starch polysaccharide iron complex, and nanofiltration permeate can be directly discharged. The specific technical solutions are:

The method for removing sodium chloride in tapioca starch polysaccharide iron complex liquid involves the application of ultrafiltration and nanofiltration membrane combination technology to remove sodium chloride and concentrate the tapioca starch polysaccharide iron complex liquid, including the following steps:

Step A, adding tapioca starch and water into the reactor, heating to 50-80 ° C, adding alkali to adjust the pH value to neutrality, adding hydrogen peroxide solution to degrade the tapioca starch at a constant temperature, to obtain the cassava with a weight average molecular weight of 3K-27KDa starch oligosaccharide solution, then add ferric chloride solution and sodium hydroxide solution simultaneously, carry out complexation reaction, obtain tapioca starch polysaccharide iron complex synthesis reaction completion liquid; tapioca starch: hydrogen peroxide: water ratio is 0.25— 0.30:0.05—0.12:1;

In step B, the tapioca starch polysaccharide iron complex liquid obtained in step A is subjected to ultrafiltration with an ultrafiltration membrane assembly, the molecular weight cut-off of the ultrafiltration membrane assembly is 2.5K~200KDa, the tapioca starch polysaccharide iron complex is intercepted by the ultrafiltration membrane, and the permeation The passing liquid is an aqueous solution containing small molecular tapioca starch polysaccharide iron complexes and sodium chloride, and the concentration and purity of tapioca starch polysaccharide iron complexes in the intercepted liquid are improved; the temperature of the feed liquid during the ultrafiltration process is 10 ~ 60 ℃, and the pressure is 0.1 ~ 1.0MPa;

In step C, the permeate of step B is subjected to nanofiltration with a nanofiltration membrane module, the molecular weight cut-off of the nanofiltration membrane is 200 Da, the nanofiltration interception liquid is a small molecule tapioca starch polysaccharide iron complex, and the nanofiltration permeate is chloride. The sodium aqueous solution, the concentration and purity of the small-molecule tapioca starch polysaccharide iron complex in the intercepted liquid are improved; in step D, the intercepted liquids of step B and step C are combined, and the solid tapioca starch polysaccharide iron complex is obtained by spray drying, and the permeate is filtered by nanofiltration. can be discharged directly. During the nanofiltration process, the temperature of the feed liquid is 10-60 °C, and the pressure is 0.1-3.0 MPa.

In the synthesis process of tapioca starch polysaccharide iron complex, tapioca starch polysaccharide is obtained from tapioca starch through hydrogen oxide degradation. During the degradation process of tapioca starch, tapioca starch polysaccharide with a wide range of molecular weight distribution will be produced, and its weight-average molecular weight distribution is generally in Between thousands and hundreds of thousands, the microfiltration membrane has no interception effect on these tapioca starch polysaccharide iron complex molecules due to the large pore size. Therefore, the microfiltration process cannot separate the tapioca starch polysaccharide iron complex molecules with chlorine. Sodium separated. Although the tapioca starch polysaccharide iron complex molecules can be separated from sodium chloride by the nanofiltration process, the water flux of the nanofiltration membrane is much lower than that of the microfiltration membrane and the ultrafiltration membrane, and the operating pressure is high. When the tapioca starch polysaccharide iron complex is When the concentration of cassava starch is high and the cassava starch raw material contains impurities such as vegetable protein, it will inevitably lead to high osmotic pressure of the solution, high operating pressure, and the phenomenon of film blocking may occur. When the iron complex synthesis reaction completion liquid is subjected to nanofiltration separation and concentration, the operating pressure is high, the separation efficiency is low, and even the nanofiltration operation cannot be carried out smoothly.

When only the ultrafiltration membrane is used to filter the completion liquid of the synthesis reaction of tapioca starch polysaccharide iron complex, although sodium chloride can pass through the ultrafiltration membrane to realize the separation of tapioca starch polysaccharide iron complex and sodium chloride, due to the ultrafiltration membrane The intercepted molecular weight is large, and some small-molecule tapioca starch polysaccharide iron complexes will pass through the ultrafiltration membrane together with sodium chloride and enter the permeate side, which will cause the loss of tapioca starch polysaccharide iron complexes, and the recovery rate On the other hand, this part of the small molecule tapioca starch polysaccharide iron complex that has passed through has a high COD concentration and a dark color, which is easy to deteriorate and corrupt, and cannot be directly discharged. It must be treated first to make the COD content lower than the wastewater discharge standard. emissions, which will incur additional treatment costs.

The use of ultrafiltration and nanofiltration membrane combination technology just solves the above problems and can play the respective advantages of ultrafiltration and nanofiltration. First, the sodium chloride is removed by the ultrafiltration membrane, and most of the tapioca starch polysaccharide iron complexes are retained. Due to the large flux of the ultrafiltration membrane and the low operating pressure, the efficiency of separation and removal of sodium chloride is very high. At the same time, the other impurities brought by the cassava starch raw material, such as vegetable protein, are retained, which is very beneficial to the subsequent nanofiltration separation operation. The osmotic pressure of sodium chloride and low-concentration small-molecule tapioca starch polysaccharide iron complexes that pass through the ultrafiltration membrane is low, and the previous ultrafiltration membrane has already blocked the impurities that may cause the nanofiltration operation. When the nanofiltration membrane is used for the nanofiltration separation of sodium chloride and small molecule tapioca starch polysaccharide iron complex, because the operating pressure is low, the nanofiltration operation can be carried out efficiently and smoothly, and the nanofiltration permeate is almost free of tapioca starch polysaccharide iron complex. The sodium chloride aqueous solution of the compound has a very low COD concentration and can be discharged directly, and the nanofiltration retentate is a concentrated aqueous solution of small molecule tapioca starch polysaccharide iron complex. The result of the combination of ultrafiltration and nanofiltration is to give full play to the advantages of both, so that the operation of separating sodium chloride from the tapioca starch polysaccharide iron complex liquid can be carried out efficiently, and the recovery rate of the tapioca starch polysaccharide iron complex is high, which can reach 99% % or more, the removal rate of sodium chloride is more than 98%.

The above-mentioned ultrafiltration membranes are inorganic ceramic membranes and organic polymer membranes, and the membrane materials include but are not limited to aluminum oxide, titanium oxide, zirconium oxide, cellulose acetate, sulfonated polysulfone, polyethersulfone, sulfonated polyethersulfone, polyethersulfone, etc. Amide, polyimide, polypiperazine and polyvinyl alcohol; the components of the ultrafiltration membrane are tubular, coiled or hollow fiber type, and the molecular weight cut off of the ultrafiltration membrane is 2.5K ~ 200KDa;

The above nanofiltration membrane is an organic composite membrane, and the membrane material is cellulose acetate, sulfonated polysulfone, polyamide, polyethersulfone, sulfonated polyethersulfone, polypiperazine or polyvinyl alcohol; Tubular type, the molecular weight cut-off of nanofiltration membrane is 200～800Da;

Among them, ultrafiltration and nanofiltration can adopt cross-flow filtration mode.

Outstanding substantive features and significant advancements of the present invention:

1. The method for removing sodium chloride in the tapioca starch polysaccharide iron complex liquid of the present invention has simple and safe operation process, energy saving and environmental protection, mild conditions and easy continuous production. The prepared cassava polysaccharide iron can be used as an iron supplement for aquaculture such as cattle, sheep, pigs or poultry, as an injection for injection, or as a feed additive as an oral liquid for cattle, sheep, and pigs, or added to the feed. , to promote the source of iron for poultry and livestock, safe and reliable, without any side effects.

2. The present invention can reduce the sodium chloride concentration in the tapioca starch polysaccharide iron complex liquid, improve the concentration of the tapioca starch polysaccharide iron complex, the total recovery rate of the tapioca starch polysaccharide iron complex is greater than 99%, and the removal rate of sodium chloride is greater than 99%. 98%, the total amount of COD in the nanofiltration permeate is small, the concentration is low, and it can be directly discharged without polluting the environment.

3. The inventors have studied that the chemical properties of tapioca starch belong to carbohydrates, and it can also be regarded as a condensation polymer of glucose. linked polymer compounds. The main structural feature of starch is that there are 1.4-glycosides between glucose units, and almost every glucose unit has C6 primary hydroxyl group and C2, C3 two secondary hydroxyl groups. The cassava starch molecule contains a large number of hydroxyl groups, and its chemical properties are active, so it is not easy to obtain suitable oligosaccharides with a weight average molecular weight of 4000-27000 Da by acid hydrolysis or enzymatic hydrolysis; therefore, the combination of ultrafiltration and nanofiltration membrane technology is used to remove cassava polysaccharide iron. The sodium chloride in the solution replaces the previous ethanol or methanol solvent method to remove sodium chloride, avoids the use of ethanol or methanol such as flammable and explosive materials, and eliminates hidden dangers in production safety.

4. Utilizing the cassava that can be planted in large quantities in the south, with abundant resources, new products have been developed and the ability of comprehensive utilization of cassava has been improved.

Description of drawings

Figure 1 is a schematic diagram of the process flow for removing sodium chloride and concentrating the tapioca starch polysaccharide iron complex liquid using the combination of ultrafiltration and nanofiltration. 1. Feed tank, 2. Feed valve A, 3. Feed pump A, 4. Ultrafiltration membrane module, 5. Check valve A, 6. Feed tank, 7. Feed valve B, 8. Feed Feed pump B, 9. Nanofiltration membrane module, 10. Check valve B.

Detailed ways

The present invention will be further described below with reference to the embodiments, and the protection scope of the subject matter involved in the present invention is not limited to these embodiments.

Description of the accompanying drawings:

The tapioca starch polysaccharide iron complex synthesis reaction completion liquid is put into the feed liquid tank 1, and there is a feed valve 2A at the outlet below the feed liquid tank 1, and is connected with the feed pump 3A, and the feed pump 3A synthesizes the tapioca starch polysaccharide iron complex. The reaction completion liquid is injected into the ultrafiltration membrane assembly 4 for ultrafiltration, and the ultrafiltrate enters the ultrafiltration material liquid tank 6. There is a feed valve 7B below the ultrafiltration material liquid tank 6, which is connected to the feeding pump 8B and hits the nanofiltration membrane assembly. 9. There is a reflux valve 5A above the ultrafiltration membrane module 4 to push the ultrafiltration water back to the feed liquid tank 1; there is also a reflux valve 10B above the nanofiltration membrane module 9 to push the nanofiltration water back to the ultrafiltration feed liquid tank 6.

Example 1

In the enamel reaction kettle, start stirring, add 750 kg of water and 220 kg of tapioca starch respectively, heat up to 60 ° C, add 75 kg of 27.5% hydrogen peroxide solution, then heat up to 60 ° C, maintain a constant temperature, and carry out oxidation reaction for 60 minutes, adding 29% sodium hydroxide seasoning solution with a pH value of 7.6 to obtain a tapioca starch polysaccharide solution with a weight-average molecular weight of 3K-27KDa, continue heating to 90°C, maintain a constant temperature, and simultaneously add 39.0% trisodium glutamate within 3 hours. 520 liters of ferric chloride solution and 560 liters of 29.0% sodium hydroxide solution were added, and the pH value of the complex reaction solution was adjusted to 7.3 with 20% hydrochloric acid to obtain a complete solution of the synthesis reaction of tapioca starch polysaccharide iron complex.

In the enamel reaction kettle, start stirring, add water, tapioca starch and hydrogen peroxide solution respectively, raise the temperature to 60°C, keep the constant temperature for reaction for a period of time, and obtain a tapioca starch polysaccharide solution with a weight average molecular weight of 3K-27KDa, continue to keep warm, and at the same time The ferric chloride solution and the sodium hydroxide solution are added for reaction to obtain the completion liquid of the synthesis reaction of the tapioca starch polysaccharide iron complex.

The cassava tapioca starch polysaccharide iron complex liquid is treated with the device shown in Figure 1, the ultrafiltration membrane module installed on the device is a multi-channel tubular ceramic ultrafiltration membrane module, the membrane support layer material is alumina, and the membrane layer material is zirconia , the molecular weight cut off of the membrane is 2500Da, and the operation mode is cross-flow filtration. 1000kg of the synthetic reaction completion liquid (sodium chloride content of 15.0%wt, iron content of 45.0mg/ml, solution density of 1.21g/ml) was subjected to an ultrafiltration operation at 45°C and a pressure of 0.40MPa, and when the permeate reached 500kg, Add 500 kg of deionized water to the concentrated solution, and continue to carry out ultrafiltration. When the permeate reaches 1000 kg, continue to add deionized water to the feed tank, and control the rate of water addition to be equal to the amount of ultrafiltration permeate until the permeate reaches 1000 kg. When the filtered liquid reaches 4000kg, the ultrafiltration operation is stopped. 500 kg of ultrafiltration intercepted liquid (concentrated liquid) (solution density 1.17g/ml) was obtained, wherein the sodium chloride concentration was 0.25wt%, the iron content was 78.30mg/ml, and the iron recovery rate was 89.90%. The color of the permeate is dark brown, the iron content is 1.10 mg/ml, the sodium chloride content is 3.72 wt %, and the COD concentration is 25500 mg/kg.

The above-mentioned ultrafiltration permeate containing 4000 kg of sodium chloride and small molecule tapioca starch polysaccharide iron complex was placed in the nanofiltration membrane device shown in Figure 1 for nanofiltration operation. The filter membrane module is roll type, the nanofiltration membrane material is sulfonated polyethersulfone, the temperature is controlled not to be higher than 50℃, and the operating pressure is controlled to be not higher than 2.0MPa. When the permeate reaches 3500kg, add deionized water to the feed tank. Water 3500kg, continue nanofiltration operation, when the total amount of permeate reaches 7150kg, stop nanofiltration. 50 kg of nanofiltration interception concentrate (solution density 1.17g/ml) was obtained, in which the iron content was 87.20 mg/ml, and the sodium chloride concentration was 0.046 wt%. The ultrafiltration and nanofiltration interception concentrates totaled tapioca starch polysaccharide iron complexes The recovery rate was 99.9%, and the sodium chloride removal rate was 99.0%. The iron content in the permeate is zero and the COD concentration is 60 mg/kg, which can be directly discharged.

Example 2-Example 9, except the process steps are the same as Example 1. Keeping the sodium chloride content 15.0 wt% in the completion liquid of the tapioca starch polysaccharide iron complex synthesis reaction, the ultrafiltration membrane module and the nanofiltration membrane module are under the same conditions as Example 1, change the temperature and the operating pressure of the treatment solution, and obtain Data are as follows:

Claims (7)

1. remove the method for sodium chloride in the tapioca starch polysaccharide iron complex liquid, is characterized in that, comprises the steps: A. Add tapioca starch and water to the reactor, heat to 50-80°C, add alkali to adjust the pH value to neutrality, add hydrogen peroxide solution to degrade the tapioca starch at a constant temperature, and obtain tapioca starch with a weight average molecular weight of 3K-27KDa oligosaccharide solution, then add ferric chloride solution and sodium hydroxide solution simultaneously, carry out complexation reaction, obtain tapioca starch polysaccharide iron complex synthesis reaction completion liquid; tapioca starch: hydrogen peroxide: the mass ratio of water is 0.0%. 25—0.30:0.05—0.12:1; B, the tapioca starch polysaccharide iron complex synthesis reaction completion liquid obtained in step A is subjected to ultrafiltration with an ultrafiltration membrane module, and the tapioca starch polysaccharide iron complex is intercepted by the ultrafiltration membrane, and water can be added for ultrafiltration and concentration at the same time. The liquid is an aqueous solution containing small molecular tapioca starch polysaccharide iron complex and sodium chloride; the ultrafiltration membrane molecular weight cut off is 2.5K～200KDa; the operating temperature in the ultrafiltration operation steps is 10～60 ℃, The operating pressure is 0.1～1.0MPa; C, the permeate of step B is subjected to nanofiltration with a nanofiltration membrane module, the nanofiltration effluent is a small molecule tapioca starch polysaccharide iron complex, and water can be added simultaneously for nanofiltration and concentration, and the nanofiltration permeate is sodium chloride aqueous solution; the molecular weight cut-off of the nanofiltration membrane is 200-800 Da; the operating temperature in the nanofiltration operation steps is 10-60° C., and the operating pressure is 0.1-3.0 MPa; D, combine the intercepted liquids of step B and step C, and obtain solid tapioca starch polysaccharide iron complex through spray drying, and the nanofiltration permeate can be directly discharged; the combination of ultrafiltration and nanofiltration membrane can make the removal rate of sodium chloride greater than 98%, the recovery rate of tapioca starch polysaccharide iron complex is greater than 99%; The cassava starch polysaccharide iron complex synthesis reaction is completed, and the liquid iron content is 20-60 mg/ml, and the sodium chloride concentration is 8-25 wt %. 2. the method for removing sodium chloride in the tapioca starch polysaccharide iron complex liquid according to claim 1, is characterized in that, described tapioca starch polysaccharide iron complex is to take tapioca starch as raw material, and obtains with hydrogen peroxide degradation The tapioca starch polysaccharide is then reacted with ferric chloride to obtain the tapioca starch polysaccharide iron complex. 3. the method for removing sodium chloride in the tapioca starch polysaccharide iron complex liquid according to claim 1, is characterized in that, described ultrafiltration membrane is inorganic ceramic membrane and organic polymer membrane, and membrane material comprises aluminium oxide, Titanium oxide, zirconium oxide, cellulose acetate, sulfonated polysulfone, polyethersulfone, sulfonated polyethersulfone, polyamide, polyimide, polypiperazine, and polyvinyl alcohol. 4. the method for removing sodium chloride in the tapioca starch polysaccharide iron complex liquid according to claim 3, is characterized in that, the assembly of ultrafiltration membrane is tubular type, roll type or hollow fiber type, and filtration mode is cross-flow filtration . 5. the method for removing sodium chloride in tapioca starch polysaccharide iron complex liquid according to claim 1, is characterized in that, described nanofiltration membrane is organic composite membrane, and membrane material is cellulose acetate, sulfonated polysulfone , polyamide, polyethersulfone, sulfonated polyethersulfone, polypiperazine or polyvinyl alcohol. 6. The method for removing sodium chloride in the tapioca starch polysaccharide iron complex liquid according to claim 5, wherein the nanofiltration membrane assembly is a roll type or a tubular type, and the filtration mode is cross-flow filtration. 7. the method for removing sodium chloride in the tapioca starch polysaccharide iron complex liquid according to claim 1, is characterized in that, the obtained tapioca starch polysaccharide iron complex can be used as the iron supplement for breeding poultry and livestock.

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