JPS626841B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a flocculant made of cationically modified guar gum with improved flocculating effect. Conventionally, various flocculants have been known as flocculants for sedimenting and separating suspended substances contained in various types of suspended water. For example, high molecular weight polyacrylamide, cationically modified polyacrylamide,
Organic flocculants such as anion-modified polyacrylamide and cation-modified dicyandiamide-formaldehyde condensate, and inorganic flocculants such as aluminum sulfate and sodium aluminate are generally used. Although inorganic flocculants are generally inexpensive,
On the other hand, organic flocculants such as those described above have a relatively good flocculating effect, but they generally have safety problems. According to JP-A-47-1961, a cationically modified starch is proposed as a flocculant. Although it has increased safety compared to commercially available organic flocculants, its flocculating effect is not satisfactory. The present inventors have conducted extensive research to develop a flocculant with excellent safety and flocculating effects, and as a result, they have developed a flocculant that uses guar gum as a base material and introduces a specific amount of quaternary nitrogen-containing groups into this flocculant. The present inventors have found that the present invention is suitable for the purpose and have completed the present invention. That is, according to the present invention, in guar gum, at least a part of the hydroxyl groups contained therein are
general formula (In the formula, R ¹ , R ² and R ₃ are each an alkyl group having 1 to 3 carbon atoms, and X represents a monovalent anion.) A flocculant made of cationically modified guar gum having a nitrogen content of 2% by weight or more is provided. The cationically modified guar gum according to the present invention can be produced by reacting guar gum with a glycidyltrialkylammonium salt or a 3-halogeno-2-hydroxypropyltrialkylammonium salt. In this case, the reaction is
It is carried out in a suitable solvent, preferably an aqueous alcohol, in the presence of an alkali. Introduction of such a quaternary nitrogen-containing group can be carried out according to a conventionally known method. In the quaternary nitrogen-containing group represented by the above general formula introduced into guar gum in the present invention, specific examples of R ¹ , R ² and R ³ include methyl, ethyl and propyl, particularly methyl group. is preferable.
Specific examples of the anion X include halogen atoms such as chlorine, bromine, and iodine, as well as methyl sulfate, ethyl sulfate, and the like. In the present invention, in order to obtain a cationically modified guar gum with an enhanced flocculating effect, it is necessary to maintain its quaternary nitrogen content at 2.0% by weight or more; It is too small to achieve the intended purpose. The flocculant made of cationically modified guar gum according to the present invention is extremely superior in both safety and flocculating effect. That is, since the flocculant according to the present invention is highly safe, it will not cause any pollution even if it remains in the treatment liquid. In addition, its flocculating effect, especially its flocculating effect on inorganic substances, is equivalent to or better than that of cation-modified polyacrylamide, which has been commonly used in the past.Furthermore, its flocculating effect on anionic surfactants is higher than that of conventional flocculants. It has been significantly enhanced. Furthermore, when using the flocculant of the present invention, since its flocculant ability is high, a large flocculating effect can be obtained with a small amount, and its flocculant-sedimentation properties are good, so
The advantage is that the resulting treatment liquid has high transparency. The flocculant according to the invention can be used alone or in combination with other flocculants, and it is also possible to apply the flocculant according to the invention after treatment with other flocculants. The flocculant according to the present invention can be applied to the treatment of various suspensions, such as sewage treatment, paper pipe waste liquid treatment, general factory wastewater treatment, etc., and in particular, the treatment of wastewater containing anionic surfactants. It has a great effect on Next, the present invention will be explained in more detail by reference examples and examples. Reference example [Manufacture of flocculant] Add 150 g of 80% by weight aqueous 2-propanol solution,
After adding 9.9 g of a 15% by weight aqueous sodium hydroxide solution and dissolving it uniformly, 37.5 g of guar gum was added with stirring and dispersed. Next, 33.7 g of glycidyltrimethylammonium chloride was added as a 75% by weight aqueous solution, heated, and reacted at 50° C. for 3 hours. After the reaction is complete, 80 g of concentrated hydrochloric acid is dissolved.
150 g of a wt % aqueous 2-propanol solution was added, and a neutralization reaction was carried out at room temperature for 1 hour. After neutralization, the product is separated and dried under reduced pressure to remove the reaction product.
50.2g was obtained. The nitrogen content of the cationized quar gum thus obtained was 4.1% by weight (sample number GUG-1).
Based on this nitrogen content, the degree of substitution of hydroxyl groups by quaternary ammonium groups was determined to be 0.85. Similarly, the nitrogen content was 3.2% by weight (GUG-
2), 2.1% by weight (GUG-3), 1.8% by weight (GUG
-4) and 1.3% by weight (GUG-5) of cationized guar gum were produced. Also, for comparison,
A cationized starch (ST) of 3.87% by weight (degree of substitution 0.77) was produced. Example 1 Using the various samples shown in Reference Examples, a flocculation test was conducted on an aqueous suspension of kaolin powder (passed through 300 meshes). In this case, the test method is as follows. A kaolin suspension with a kaolin content of 5 g was placed in a graduated cylinder with an inner diameter of 2.5 cm and an inner volume of 100 ml, and a sample aqueous solution was added to the cylinder at a concentration of 5 g.
It was added to give a concentration of 1 ppm, and water was further added to bring the total volume to 100 ml. This cylinder for 40 seconds
After stirring by inverting 10 times, the mixture was allowed to stand, and the sedimentation rate of the particles and the turbidity of the supernatant liquid after standing for 10 minutes were measured. The sedimentation velocity was determined by reading the sedimentation surface of the kaolin particles from the scale of the cylinder, dotting the amount of descent of the sedimentation surface on a graph in relation to time, and determining the initial velocity (cm/min) at time 0. The turbid supernatant liquid was collected from the cylinder scale 80 after standing for 10 minutes, and measured using a haze meter (manufactured by Nippon Denshoku Co., Ltd.). The measurement temperature was 25℃, and the PH of the kaolin suspension was
It was 6.0. For comparison, a cationically modified product of commercially available polyacrylamide (sample number
A similar test was conducted using PA). The test results described above are shown in Table 1. Note that the turbidity shown in the table was calculated by setting the value for pure water as 0, and the larger the value, the more severe the turbidity.

[Table] As is clear from the results shown in Table 1, in order to obtain cationized guar gum with good cohesion, the nitrogen content must be at least 2% by weight; It can be seen that the cationized guar gum shown in the figure shows a significantly superior flocculation effect compared to cationized starch, and that the flocculation effect is comparable to that of a commonly used commercially available cation-modified polyacrylamide. Example 2 A flocculation test was conducted on cationized guar gum (GUG-1) in the same manner as in Example 1, and the relationship between the amount added and the flocculation effect was investigated. The results are shown as a graph in the drawing. For comparison, the results obtained when a commercially available product (PA) was used are also shown in the drawing. In the drawing, the horizontal axis is the flocculant GUG-1 or PA
The left vertical axis shows the sedimentation rate (cm/min), and the right vertical axis shows the turbidity (%). In addition, curve-1 and curve-2 show the test results for GUG-1, curve-1 is the sedimentation rate, and curve-2 is the test result for GUG-1.
2 shows the measured value of turbidity. Curve-3 and Curve-4
shows the test results for PA, curve-3 shows the sedimentation rate, and curve-4 shows the measured values of turbidity. From the results shown in this graph, it can be seen that the flocculant GUG-1 according to the present invention has a flocculating effect equal to or higher than that of commercially available PA. Example 3 Among the samples shown in Example 1, GUG-1, GUG
-3 and GUG-4 were selected, and a cohesive force test was conducted against anionic surfactants. The cohesion test in this case is as follows. Put 20 ml of a 0.05% aqueous solution of sodium dodecylbenzenesulfonate (LAS-Na) into a beaker with an internal volume of 200 ml, then add a predetermined amount of a 0.1% aqueous solution of the sample, and then add water so that the total amount is 100 g. A complex between the sample and LAS-Na is formed, and the system becomes cloudy or a precipitate is formed. After stirring this solution for 15 minutes, it was suctioned using paper (No. 5C, manufactured by Toyo Paper Co., Ltd.) to remove the LAS−Na in the solution.
Measure the concentration and turbidity of the solution. The smaller these measured values are, the better the aggregation effect is. Further, for comparison, a similar test was conducted using ST and PA. The results of these tests are shown in Table 2.

【table】

[Table] Yes.
As is clear from the results shown in Table 2, cationized guar gums (GUG-1, GUG-3) with a nitrogen content of 2.0% by weight or more exhibit good aggregation properties with anionic surfactants. Okay, and in this case, the particle size of the composite formed from the anionic surfactant and cationized guar gum is large;
It can be seen that it is easily removed by filtration and that the liquid has high clarity. Example 4 GUG-1, GUG-3, and GUG shown in Example 1
-4 was combined with an inorganic flocculant (aluminum sulfate), and a cohesive force test for the anionic surfactant was conducted in the same manner as in Example 3. in this case,
Aluminum sulfate was added to the sample in the form of a 1% aqueous solution.
After stirring the solution containing the complex with LAS-Na for 15 minutes, add it to the solution (addition amount 1 ml). Add 5 drops of aqueous solution and adjust its pH to 8.5
Adjusted to ±0.3. For comparison, a similar test was conducted using ST and PA instead of GUG. The test results are shown in Table 3.

【table】

[Table] Yes.
As is clear from the results shown in Table 3, the combined use of aluminum sulfate increases the cohesive force of each sample toward the anionic surfactant, but even in this case, the nitrogen content is 2.0% by weight or more. Cationized guar gum (GUG-1, GUG-3)
It can be seen that this shows a significantly enhanced flocculation effect.

[Brief explanation of the drawing]

The drawing is a graph showing the relationship between the amount of flocculant added and the flocculating effect, where curves 1 and 2 show the results for the flocculant of the present invention, and curves 3 and 4 for the commercially available flocculant.

Claims (1)

[Claims] 1. In guar gum, at least a part of the hydroxyl groups contained therein have the general formula (In the formula, R ¹ , R ² and R ³ are each an alkyl group having 1 to 3 carbon atoms, and X represents a monovalent anion), and the nitrogen A flocculant consisting of cationically modified guar gum having a content of 2% by weight or more.