Reagent and method for judging residual flocculant in washed sand

Abstract

The invention provides a judgment reagent and a judgment method for flocculant residues in washed sand. The judgment reagent comprises the following components in parts by mass: 2-10 parts of a masking agent, 3-6 parts of activated carbon, 15-30 parts of a buffer solution, 1-5 parts of a chromogenic reagent and 30-60 parts of a competitive reaction solution, the judgment method comprises the following steps: taking a sand washing sample, adding water, stirring, sequentially adding the masking agent, the activated carbon, the buffer solution, the color developing reagent and the competitive reaction solution, and judging the flocculant residue by observing whether precipitate is generated or the color is changed. The device has the advantages of rapidness, portability, economy and easiness in operation, and is suitable for field use.

Description

Technical Field

[0001] The invention relates to the technical field of materials engineering, and particularly relates to a reagent and a method for judging the residue of flocculant in washed sand. Background Art

[0002] At present, the use of washed machine-made sand in concrete production has gradually become normal, but there are still some problems in the current situation of the use of flocculants in the washed machine-made sand process. Although flocculants can effectively solve the problems of water resource waste and sewage recycling in the production of washed machine-made sand, the selection of flocculant types and the control of dosage by production enterprises are not stable, resulting in a large residual amount of flocculants in the finished washed sand, which seriously affects the performance of building materials such as concrete. Although the detection technology of flocculants is relatively mature, there are still many problems in the existing detection methods. For example, the sample preparation of the infrared spectroscopy method is complex and the equipment is expensive, and the chemical titration method is complex to operate, and neither is suitable for use in the field environment. Therefore, it is of great practical significance to develop a rapid, simple and field-applicable method for judging the residue of flocculants. Summary of the Invention

[0003] Object of the Invention: The present invention aims to solve the deficiencies of the prior art and provides a reagent and a method for judging the residue of flocculant in washed sand. Through the synergistic effect of a masking agent, activated carbon, buffer solution, chromogenic reagent and competitive reaction solution, the present invention realizes the rapid judgment of the residue of flocculant.

[0004] The technical solution of the present invention is as follows: The components and mass ratio of the reagent for the judgment method of the present invention are: 2-10 parts of masking agent, 3-6 parts of activated carbon, 15-30 parts of buffer solution, 1-5 parts of chromogenic reagent, and 30-60 parts of competitive reaction solution.

[0005] A method for judging the residue of flocculant in washed sand disclosed by the present invention includes the following steps: (1) Take 250 g of washed sand as a sample, pour it into container N, add 500 mL of water and stir evenly to obtain solution A; (2) Add a masking agent to solution A, shake well and let stand for 5 min to obtain solution B; (3) Add activated carbon powder to solution B, stir for 10-20 min and let stand until the solution is clear to obtain solution C; (4) Take 50 mL of the supernatant of solution C into container M, then add a buffer solution to container M, shake well, add a chromogenic solution, shake well again, and let stand for 5 min to obtain solution D; (5) Add the competitive reaction solution to solution D, shake well, and let it stand for 10-15 min to observe whether there is precipitation or color change. If precipitation or color change occurs, it is judged that the washed sand contains flocculant residues; otherwise, it is judged that there is no flocculant.

[0006] Furthermore, the flocculant is anionic polyacrylamide; Furthermore, in step (2), the masking agent is one or more of disodium oxalate tetraacetate, sodium citrate, tartaric acid, potassium sodium tartrate, etc.; Furthermore, in step (3), the activated carbon is powdered activated carbon with a particle size of less than 0.15 mm; Furthermore, in step (4), the buffer solution is one or more of acetate buffer, phosphate buffer, citrate buffer, etc.; Furthermore, in step (4), the color developing solution is one of acid blue, bromophenol blue, dadan yellow and methyl orange; Furthermore, in step (5), the competitive reaction solution is one or two of polyethyleneimine, polydimethylamine, polyethylenediamine, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride.

[0007] Compared with the prior art, the method for determining the residual flocculant in washed sand of the present invention has the following beneficial technical effects: (1) The determination method provided by the present invention has clear steps and is simple to operate. It does not require complex instruments and equipment, and can be completed with only conventional laboratory containers and reagents. Compared with the high-cost instruments or complex operation procedures that may be involved in the prior art, the present invention is more suitable for on-site rapid detection.

[0008] (2) By adding masking agents and activated carbon powder, the influence of other interfering substances (such as metal ions, humic acid, etc.) in washed sand is effectively eliminated, thereby improving the accuracy of detection. At the same time, the use of cationic surfactants in the color development solution and the competitive reaction solution enhances the sensitivity of detection, making precipitation or discoloration easier to observe.

[0009] (3) The polyamines contained in the competitive reaction solution used in this method have a positive charge, while the anionic polyacrylamide to be detected has a negative charge. When a relatively large amount of polyamines in the solution comes into contact with a relatively small amount of polyacrylamide, the concentration effect is aggravated, and the two react to neutralize the charge quickly after mixing to form an insoluble complex. The addition of the buffer solution as a stabilizer ensures that the polyamine reaction reagent has a positive charge, thereby enhancing the reaction efficiency. DETAILED DESCRIPTION

[0010] The present invention will be further described below with reference to specific embodiments.

[0011] Example 1 A method for determining residual flocculant in washed sand comprises the following steps: (1) Take 250 g of washed sand containing 0.05% residual flocculant as a sample, pour it into a container, add 500 mL of water and stir evenly; (2) Add 5 parts of disodium oxalate tetraacetate to the solution in step (1), shake well and let stand for 5 minutes; (3) Add 4 parts of powdered activated carbon (particle size less than 0.15 mm) to the solution in step (2), stir for 15 min and let stand until the solution becomes clear; (4) Take 50 mL of the supernatant from step (3) into another container, add 20 parts of acetate buffer, shake well, add 3 parts of bromophenol blue solution, shake well, and let stand for 5 min; (5) Add 40 parts of polyethyleneimine to the solution in step (4), shake well, let stand, and observe whether there is precipitation or color change.

[0012] Example 2 A method for determining residual flocculant in washed sand comprises the following steps: (1) Take 250 g of washed sand containing 0.05% residual flocculant as a sample, pour it into a container, add 500 mL of water and stir evenly; (2) Add 8 parts of sodium citrate to the solution in step (1), shake well and let stand for 5 minutes; (3) Add 5 parts of powdered activated carbon (particle size less than 0.15 mm) to the solution in step (2), stir for 20 minutes and then let stand until the solution becomes clear; (4) Take 50 mL of the supernatant from step (3) into another container, add 20 parts of phosphate buffer, shake well, add 2 parts of bromophenol blue solution, shake well, and let stand for 5 min; (5) Add 50 parts of polyethyleneimine to the solution in step (4), shake well, let stand, and observe whether there is precipitation or color change.

[0013] Example 3 A method for determining residual flocculant in washed sand comprises the following steps: (1) Take 250 g of washed sand containing 0.05% residual flocculant as a sample, pour it into a container, add 500 mL of water and stir evenly; (2) Add 3 parts of tartaric acid to the solution in step (1), shake well and let stand for 5 minutes; (3) Add 6 parts of powdered activated carbon (particle size less than 0.15 mm) to the solution in step (2), stir for 20 min and let stand until the solution becomes clear; (4) Take 50 mL of the supernatant from step (3) into another container, add 15 parts of citric acid buffer, shake well, add 1 part of Dadan yellow solution, shake well, and let stand for 5 minutes; (5) Add 30 parts of polydimethylamine to the solution in step (4), shake well, let stand, and observe whether there is precipitation or color change.

[0014] Example 4 A method for determining residual flocculant in washed sand comprises the following steps: (1) Take 250 g of washed sand containing 0.05% residual flocculant as a sample, pour it into a container, add 500 mL of water and stir evenly; (2) Add 10 parts of sodium citrate to the solution in step (1), shake well and let stand for 5 minutes; (3) Add 3 parts of powdered activated carbon (particle size less than 0.15 mm) to the solution in step (2), stir for 20 min and let stand until the solution becomes clear; (4) Take 50 mL of the supernatant from step (3) into another container, add 30 parts of phosphate buffer, shake well, add 2 parts of bromophenol blue solution, shake well, and let stand for 5 min; (5) Add a mixture of 40 parts of polyethyleneimine and 10 parts of hexadecyltrimethylammonium bromide to the solution in step (4), shake well and let stand to observe whether there is precipitation or color change.

[0015] Example 5 A method for determining residual flocculant in washed sand comprises the following steps: (1) Take 250 g of washed sand containing 0.05% residual flocculant as a sample, pour it into a container, add 500 mL of water and stir evenly; (2) Add 10 parts of disodium oxalate tetraacetate to the solution in step (1), shake well and let stand for 5 minutes; (3) Add 5 parts of powdered activated carbon (particle size less than 0.15 mm) to the solution in step (2), stir for 15 min and let stand until the solution becomes clear; (4) Take 50 mL of the supernatant from step (3) into another container, add 20 parts of phosphate buffer, shake well, add 2 parts of methyl orange solution, shake well, and let stand for 5 min; (5) Add 50 parts of polyethylenediamine and 10 parts of hexadecyltrimethylammonium chloride to the solution in step (4), shake well and let stand to observe whether there is precipitation or color change.

[0016] Comparative Example 1: The steps of this comparative example are basically the same as those of Example 1, except that the washed sand containing 0.05% residual flocculant is replaced by washed sand containing 0%, 0.01%, 1%, and 2% residual flocculant, respectively.

[0017] Comparative Example 2: The steps of this comparative example are basically the same as those of Example 4, except that the washed sand containing 0.05% residual flocculant is replaced by washed sand containing 0%, 0.01%, 1%, and 2% residual flocculant, respectively.

[0018] Table 1 is the observation results of Examples 1-5 Table 2 is the observation results of Comparative Example 1 Table 3 is the observation results of Comparative Example 2 As can be seen from Table 1, all examples generated precipitation when containing 0.05% residual flocculant, indicating that this method can effectively determine the presence of flocculants. In addition, examples 4 and 5 also showed color changes, further enhancing the accuracy of the determination.

[0019] As shown in Table 2, the results of Comparative Example 1 show that when the residual amount of flocculant is less than 0.01%, the solution remains clear and has no color change; and when the residual amount reaches 1% or more, precipitation appears in the solution. This shows that this method has a certain sensitivity in judging the residual amount of flocculant and can distinguish the residual conditions of different concentrations.

[0020] The results in Table 3 show that even if the residual amount of Example 5 is only 0.01%, the color of the solution will change (the blue color becomes lighter), indicating that this method is more sensitive to the judgment of low-concentration flocculants. This may be due to the fact that the surfactant and polyamine solution in the reaction solution competitively bind with the residual flocculant in the solution, resulting in a slight change in the color of the solution.

[0021] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A reagent for determining the residual flocculant in washed sand, characterized in that: The mass proportions of the components of the determination reagent are: 2-10 parts of masking agent, 3-6 parts of activated carbon, 15-30 parts of buffer solution, 1-5 parts of colorimetric reagent, and 30-60 parts of competitive reaction solution.

2. The reagent for determining the residual flocculant in washed sand according to claim 1, characterized in that: The masking agent is one or more of disodium oxalate tetraacetate, sodium citrate, tartaric acid and potassium sodium tartrate.

3. The reagent for determining the residual flocculant in washed sand according to claim 1, characterized in that: The activated carbon is powdered activated carbon with a particle size less than 0.15 mm.

4. The reagent for determining the residual flocculant in washed sand according to claim 1, characterized in that: The buffer solution is one or more of acetate buffer, phosphate buffer and citrate buffer.

5. The reagent for determining the residual flocculant in washed sand according to claim 1, characterized in that: The color developing reagent is acid blue, bromophenol blue, dadan yellow or methyl orange.

6. The reagent for determining the residual flocculant in washed sand according to claim 1, characterized in that: The competitive reaction solution is one or two of polyethyleneimine, polydimethylamine, polyethylenediamine, hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride.

7. A method for determining residual flocculant in washed sand, characterized in that: The determination reagent according to any one of claims 1 to 6, specifically comprising the following steps: (1) Take 250 g of washed sand as a sample, pour it into container N, add 500 mL of water and stir evenly to obtain solution A; (2) Add masking agent to solution A, shake well and let stand for 5 min to obtain solution B; (3) Add activated carbon powder to solution B, stir for 10-20 min, and let stand until the solution becomes clear to obtain solution C; (4) Take 50 mL of the supernatant of solution C into container M, then add the buffer solution to container M, shake well, add the color developing solution, shake well again, and let stand for 5 min to obtain solution D; (5) Add competitive reaction solution to solution D, shake well and let stand for 10-15 min to observe whether there is precipitation or color change. If precipitation or color change occurs, it is judged that the washed sand contains flocculant residue; otherwise, it is judged that there is no flocculant.

8. The method for determining residual flocculant in washed sand according to claim 7, characterized in that: The flocculant is anionic polyacrylamide.

Images