CN1192979C - Organic-inorganic composite flocculant and its preparing process - Google Patents

Abstract

The present invention relates to an organic-inorganic composite flocculant and a production method thereof. The flocculant comprises a polymer of dicyanodiamine and formaldehyde, polyaluminum sulfate chloride and/or aluminium calcium chloride polysulfide. The production method comprise the following technological steps: hydrolytic reaction, polymerization reaction and polycondensation reaction. The technological steps which can be carried out in sequence can also be carried out in the sequence of the hydrolytic reaction, the polycondensation reaction and the polymerization reaction or the sequence of the polycondensation reaction, the hydrolytic reaction and the polymerization reaction. The flocculant has the advantages of the existing inorganic flocculant and organic flocculant, and is especially suitable for treating waste water with high alkalinity and high chromaticity. The production method and the technology of the flocculant are simple, and conventional equipment is used without the discharge of three kinds of waste.

Description

Organic-inorganic composite flocculant and its production method

Technical field

The invention belongs to the field of flocculants, in particular to a flocculant for waste water treatment and a production method thereof.

Background technique

Flocculants have been widely used in wastewater treatment. As far as the existing flocculants are concerned, they can be divided into two categories: inorganic flocculants and organic flocculants according to their chemical composition. Among the inorganic flocculants, inorganic polymer flocculants are dominant, such as polysulfuric ferric chloride, polyphosphoric ferric chloride, polyferric silicate, polyferric phosphate and other iron salts and polyferric aluminum chloride, polysilicon Aluminum salt flocculants such as aluminum sulfate and aluminum polyphosphate sulfate. Although this type of flocculant can effectively disinfect, sterilize, and purify wastewater, it has disadvantages such as large dosage, low efficiency, and high scum generation. The main varieties of organic polymer flocculants are polyacrylamide (PAM), polymethacrylate-acrylonitrile copolymer, polyester polyamine, polyvinyl benzyl quaternary ammonium salt, etc., which are combined with inorganic polymer flocculants Compared with it, it has the advantages of small dosage, strong flocculation ability, high efficiency, and less scum generation, but the disadvantage is that the waste residue has a high moisture content and the generated sewage volume is relatively large.

Contents of Invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide an organic-inorganic composite flocculant and its production method. This flocculant has the advantages of existing inorganic flocculants and organic flocculants, and is especially suitable for high alkalinity 1. The treatment of high chroma wastewater, the production method is simple, the conventional equipment is used, and there is no waste gas, waste water, and waste residue discharge.

The organic-inorganic composite flocculant provided by the present invention includes a polymer of dicyandiamide and formaldehyde and polyaluminum calcium chloride calcium, which is transparent and viscous. The general chemical formula of the polymer of dicyandiamide and formaldehyde is [ C ₃ H ₆ N ₄ O] _n , 5≤n≤10 and an integer.

The production method of the above-mentioned composite flocculant is to compound organic flocculant and inorganic flocculant by "one-bath synthesis method". There are two specific processes.

1. The first process

1. Raw materials and their formula (mass fraction)

Aluminum sulfate 5～15%

Calcium chloride 10～20%

Dicyandiamide 2～8%

Formaldehyde 2～9%

Water balance

2. Process steps and process parameters

The following process steps are sequentially included, and each process step is carried out under normal pressure.

(1) Hydrolysis reaction

Put the aluminum sulfate into water at 50-65°C, and hydrolyze it under stirring. After the aluminum sulfate is dissolved, adjust the pH value of the solution with acid or alkali, and control the pH value at 1.0-3.0.

(2) Polymerization reaction

Calcium chloride is added to the hydrolyzate of aluminum sulfate under stirring, the temperature is raised to 90°C-100°C, and then a polymerization accelerator is added, and the reaction time is 1-3 hours.

(3) Polycondensation reaction

Add the solvating agent and dicyandiamide to the above solution under stirring, add formaldehyde after dissolution, and react at 90°C-100°C for 5-hours to obtain the product.

In this process, the acid used to adjust the pH value of the hydrolysis solution is an organic acid or an inorganic acid. The organic acid can be formic acid, acetic acid, oxalic acid, tartaric acid, or citric acid. The inorganic acid can be sulfuric acid, hydrochloric acid, or phosphoric acid. Sodium hydroxide, the polymerization accelerator is water glass or rare earth salt solution, the addition of water glass is 1～2% (mass fraction), the rare earth salt solution can be light rare earth salts such as cerium salt, and its addition is 0.1～0.2% (mass fraction); the solvating agent is an inorganic ammonium salt, which can be selected from ammonium sulfate or ammonium chloride or ammonium bisulfate or ammonium dihydrogen phosphate, etc., and its addition is 1 to 2% (mass fraction).

2. The second process

1. Raw materials and their formula (mass fraction)

Aluminum salt 10～30%

Dicyandiamide 6～15%

Formaldehyde 8～16%

Water balance

2. Process steps and process parameters

The process steps include hydrolysis reaction, polymerization reaction and polycondensation reaction. The above process steps have two sequences, one sequence is polycondensation reaction → hydrolysis and polymerization reaction, and the other sequence is hydrolysis reaction → polycondensation and polymerization reaction. Each process step is in Under normal pressure.

(1) Polycondensation reaction → hydrolysis and polymerization reaction

A. Polycondensation reaction

First, heat the water to 90°C-100°C and add acid to adjust the pH value, the pH is controlled at 1.0-2.0, then add dicyandiamide under stirring, add formaldehyde after it is dissolved, and keep warm at 90°C-100°C for 4-5 Hours to complete the polycondensation reaction.

B. Hydrolysis and polymerization reaction

Add the aluminum salt into the solution obtained by the polycondensation reaction under stirring, then lower the temperature of the solution to 80°C-90°C and keep it warm for 2-3 hours to obtain the product.

(2) Hydrolysis → Polycondensation and Polymerization

A. Hydrolysis reaction

Firstly, the water is heated to 90°C-100°C and acid is added to adjust the pH value, the pH value is controlled at 0.5-1.0, and then the aluminum salt is added under stirring, and the hydrolysis solution is obtained after the aluminum salt dissolves.

B. Polycondensation and polymerization reactions

Add dicyandiamine to the above hydrolysis solution under stirring, add formaldehyde for 0.5-1 hour of dissolution reaction, and react at 90°C-100°C for 5-7 hours to obtain the product.

In the process, the aluminum salt is aluminum sulfate or aluminum chloride; the acid used to adjust the pH value of the water is an organic acid or an inorganic acid. The organic acid can be formic acid or acetic acid or oxalic acid or tartaric acid or citric acid. The inorganic acid can be sulfuric acid or hydrochloric acid or phosphoric acid etc.

The present invention has the following advantages and positive effects:

1. The consumption of chemicals is low during wastewater treatment, and the amount of compound flocculant added is only 10-800mg/L.

2. The effect of wastewater treatment is ideal. The indicators of treated wastewater are 96% to 100% reduction in SS; 76% to 88% reduction in COD _Cr ; 70% to 82% reduction in BOD; 96% to 100% reduction in chroma . Especially for wastewater with high alkalinity and high chroma, the treated water can be reused.

3. Compared with organic polymer flocculants, the water content of waste residue can be reduced by 40% to 60%, and the volume of sludge can be reduced by 50% to 60%.

4. For wastewater with high alkalinity and high chroma, the treated waste residue can be used as raw materials for synthetic fuels, super absorbents, pigment fillers and other products, turning waste into treasure.

5. The product has good stability, is non-toxic and has a slight fragrance. The use is not restricted by seasons and regions, and it is convenient for storage and transportation.

6. The production process is simple, the production raw materials are easy to obtain, the production cycle is short, the reaction is mild, and the required equipment is conventional equipment, which is convenient for the existing chemical plant to start production.

7. There is no waste gas, waste water and waste residue discharge in the whole process, which is a clean production process without pollution.

Description of drawings

Fig. 1 is a kind of process flow diagram of the production method of the organic-inorganic composite flocculant proposed according to the present invention;

Fig. 2 is the second process flow diagram of the production method of the organic-inorganic composite flocculant proposed according to the present invention;

Fig. 3 is a third process flow chart of the production method of the organic-inorganic composite flocculant proposed according to the present invention.

Detailed ways

The present invention is further illustrated below with examples.

Example 1:

The raw material of this embodiment and formula (mass fraction) thereof:

Aluminum Sulfate 10%

Calcium Chloride 15%

Dicyandiamide 5%

Formaldehyde 5%

Water balance

Process steps and process parameters of the present embodiment:

The process steps and sequence of this embodiment are shown in Figure 1, and each process step is carried out under normal pressure.

(1) Hydrolysis reaction

Add the required water into the reaction kettle, the water temperature is controlled at 60°C, and then add aluminum sulfate under stirring. When the aluminum sulfate is dissolved, test the pH value of the solution, and adjust the pH value to 2.5 with hydrochloric acid or sodium hydroxide.

(2) Polymerization reaction

Calcium chloride is added to the above hydrolyzate under stirring, then the temperature is raised to 95° C. and water glass with a mass fraction of 1.0% is added to promote polymerization. The reaction time is 2 hours.

(3) Polycondensation reaction

Add 1.2% ammonium sulfate solvating agent and dicyandiamide to the solution after the polymerization reaction is completed under stirring, add formaldehyde after dissolution, and keep warm at 95°C for 6 hours to obtain a composite flocculant product.

Example 2:

The raw material of this embodiment and formula (mass fraction) thereof:

Aluminum Chloride 20%

Dicyandiamide 10%

Formaldehyde 10%

Water balance

Process steps and process parameters of the present embodiment:

The process steps and sequence of this embodiment are shown in Figure 2, and each process step is carried out under normal pressure.

(1) Polycondensation reaction

Add the required water into the reaction kettle, control the water temperature at 100°C, add formic acid to adjust the pH value of the water to 1.5, then add dicyandiamide under stirring, add formaldehyde after it is dissolved, and keep it warm at 100°C for 4 hours. Complete the polycondensation reaction.

(2) Hydrolysis and polymerization reaction

Add aluminum chloride to the solution obtained by the polycondensation reaction under stirring, then lower the temperature of the solution to 80°C and keep it warm for 3 hours to obtain the composite flocculant product.

Example 3:

The raw material of this embodiment and formula (mass fraction) thereof:

Aluminum Chloride 15%

Dicyandiamide 8%

Formaldehyde 10%

Water balance

Process steps and process parameters of the present embodiment:

The process steps and sequence of this embodiment are shown in Figure 3, and each process step is carried out under normal pressure.

(1) Hydrolysis reaction

Add the required water into the reaction kettle, control the water temperature at 90°C, add industrial concentrated sulfuric acid to adjust the pH value of the water to 1.0, then add aluminum chloride under stirring, and the hydrolysis solution will be obtained after the aluminum chloride dissolves.

(2) Polycondensation and polymerization reaction

Add dicyandiamide to the above hydrolysis solution under stirring, add formaldehyde at 1 hour of the dissolution reaction, and keep the reaction at 90°C for 7 hours to obtain the composite flocculant product.

Claims (6)

1. An organic-inorganic composite flocculant, characterized in that it comprises a polymer of dicyandiamide and formaldehyde and polyaluminum calcium chloride calcium, which is transparent and viscous. The chemical properties of the polymer of dicyandiamide and formaldehyde The formula is [C ₃ H ₆ N ₄ O] _n , 5≤n≤10 and is an integer. 2. A method for producing an organic-inorganic composite flocculant according to claim 1, characterized in that: (1) Raw materials and their formulations, the following formulations are in mass fraction, Aluminum sulfate 5～15% Calcium Chloride 10～20% Dicyandiamide 2～8% Formaldehyde 2～9% Water balance (2) Process steps and process parameters Include the following process steps in turn, each process step is carried out under normal pressure, A. Hydrolysis reaction Put the aluminum sulfate into water at 50-65°C, and hydrolyze it under stirring. After the aluminum sulfate is dissolved, adjust the pH value of the solution with acid or alkali, and control the pH at 1.0-3.0. B. Polymerization reaction Add calcium chloride to the hydrolyzate of aluminum sulfate under stirring, raise the temperature to 90°C to 100°C, then add a polymerization accelerator, and the reaction time is 1 to 3 hours. C. Polycondensation reaction Add the solvating agent and dicyandiamide to the above solution under stirring, add formaldehyde after dissolution, and react at 90°C to 100°C for 5 to 8 hours to obtain the product. 3. The production method of organic-inorganic composite flocculant according to claim 2, characterized in that the polymerization accelerator is water glass or rare earth salt solution, the amount of water glass added is 1 to 2% by mass fraction, and the amount of rare earth salt solution is The added amount is 0.1-0.2% by mass fraction. 4. The production method of organic-inorganic composite flocculant according to claim 2 or 3, characterized in that the solvating agent is inorganic ammonium salt, and the addition amount is 1-2% by mass fraction. 5. The production method of organic-inorganic composite flocculant according to claim 2 or 3, characterized in that the acid used to adjust the pH value is an organic acid or an inorganic acid. 6. The production method of organic-inorganic composite flocculant according to claim 4, characterized in that the acid used to adjust the pH value is an organic acid or an inorganic acid.

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