JP2000000404A - Titanium-containing flocculant for water treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the raw tap water purifying performance of a flocculant by hydrolyzing titanium sulfate in an aq. soln. at a specified pH, deflocculating a formed precipitate of titanium oxide hydrate with hydrochloric acid and using the resultant colloid having a specified average particle diameter as the flocculant. SOLUTION: When a high performance flocculant having-high safety and no problem of coloring is produced, an aq. titanium sulfate soln. is adjusted to pH 3-8 with sodium hydroxide and heated to 60-80 deg.C to precipitate titanium oxide hydrate. This formed precipitate is recovered and washed until it is made free from sulfuric acid radicals. The washed titanium oxide hydrate cake is suspended again in water and 20-45 wt.% hydrochloric acid represented by HCl/TiO2 is added to the suspension. The hydrochloric acid added suspension is aged at 60-95 deg.C for 30-120 min to obtain titanium oxide colloidal particles having 30-70 nm particle diameter. Up to 200 wt.% hydrochloric acid represented by HCl/TiO2 is further added if necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coagulant for water treatment,
In particular, the present invention relates to a flocculant for purification of tap water.

[0002]

2. Description of the Related Art At present, aluminum-based coagulants such as aluminum chloride and aluminum sulfate and iron-based coagulants such as iron chloride and iron sulfate are used for water purification treatment and wastewater treatment. Further, titanium tetrachloride [TiCl ₄ ], titanyl chloride [TiOCl ₂ ], titanium sulfate [Ti (S
O ₄ ) ₂ ], titanyl sulfate, [TiO (S
It is well known that O ₄ )] can be used as a coagulant for water treatment. (JP-A-59-49811,
JP-A-9-168786 and JP-A-9-23937
No. 3, JP-A-10-137508)

[0003]

The causal relationship between aluminum and Alzheimer's dementia has been concerned about aluminum-based coagulants, and the Ministry of Health has been paying attention. Iron-based flocculants are unsuitable for washing and the like due to coloring by iron components. Also,
In the case of titanic acid-based flocculants, the flocculation ability in the neutral pH range is not sufficient, so that it is necessary to use a large amount of an auxiliary agent, and further improvement is required for industrial use. Accordingly, there is a need for safer and higher performance new flocculants as substitutes for these.

[0004]

Means for Solving the Problems The present inventors have selected titanium having high safety and no problem of coloring as a metal species, and have intensively studied the relationship between various titanium compounds and their cohesive ability. As a result, titanium oxide-based colloidal particles generated by performing a special treatment using titanium sulfate as a starting material,
The present inventors have found that they exhibit excellent performance as a novel coagulant for water treatment, and have reached the present invention.

That is, titanium sulfate (T
iO ₂ min: 10 to 30 wt%, H ₂ SO ₄ min: 15 to 45
wt%) and neutralized with 5-20 wt% sodium hydroxide to a pH in the range of 3 to 8 to form a precipitate formed of TiO ₂
60-95% after peptization with 20-45 wt% hydrochloric acid
It was confirmed that titanium oxide-based colloidal particles having a particle diameter of 20 to 70 nm obtained by aging at 30 ° C for 30 to 120 minutes can be used as a coagulant for water treatment to solve the above-mentioned problems. The titanium oxide colloid particles were confirmed to be orthotitanic acid by X-ray diffraction measurement. It was confirmed that the production conditions and characteristics of the titanium oxide-based colloid particles exhibiting the optimum aggregating ability were as follows.

Table 1 Conditions and characteristics of optimum colloidal particles の 中 In titanium sulfate PH value at the time of summation: 3.5-7.0 Aging hydrochloric acid concentration during peptization: 35-45 wt% (vs. TiO ₂ ) Aging time: 40-60 minutes Aging temperature: 70-90 ° C. Potential: -10 to +10 mV Average particle size: 30 to 50 nm Particle size distribution: 30 nm or less 2.0 wt% 30 to 40 nm 48.0 wt% 40 to 50 nm 47.6 wt% 50 nm or more 2.4 wt% ────────────────────────────

The amount of the titanium oxide-based coagulant of the present invention is as follows:
Usually, ₂ to 5 pp as TiO2 to raw water for drinking water
m, preferably 3 ppm, is sufficient, and the method of addition is not particularly limited. In order to enhance the effect of the coagulant, the stirring at the time of adding it to the purified water is preferably as strong as possible, and the coagulation ability is improved by a device such as injection in the middle of a water pipe on the inlet side of the circulation pump. The aggregating ability of the colloidal hydrated titanium oxide of the present invention in raw water of the Yodogawa water system was superior to the sulfate band, and was found to have the same or better aggregating ability as the aluminum-based flocculant.

[0008] The safety data of the titanium-based flocculant of the present invention are as follows, and the safety is high and there is no problem of coloring. LD ₅₀ : 3.321 g / kg (rat) Ames test: negative Carcinogenicity: Listed in Table-3 (W
HO)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to typical examples, but it is not intended that the present invention be limited by the examples described below.

[0010] Table 2 Coagulation test method ─────────────────────────────────── Type of raw water: Elutriated kaolin (Kanto Chemical Co., Ltd.) / Tap water Turbidity: 29.3 degrees pH: 7.2 Alkalinity: 30 mg / L Raw water amount: 500 mL Tester: Jar tester (Miyamoto Riken Co., Ltd. JMD-8) Stirring conditions: Rapid stirring 110 rpm, 10 minutes Slow stirring 40 rpm, 10 minutes Stand still 10 minutes Turbidimeter: SEP-PT-501D manufactured by Mitsubishi Kasei Kogyo Evaluation: Flock sedimentation ○: Good △: Average ×: Poor ─────────────────────────────

Coagulants for comparison: Aluminum sulfate (manufactured by Daimei Chemical Co., Ltd.) Titanium sol (manufactured by Teica Co., Ltd.) Titanium sulfate manufactured by Teika Co., Ltd. is thermally hydrolyzed at 105 ° C., and then the sulfuric acid content is 48 wt% hydroxylated. Neutralized with sodium, washed with water, 10 wt% of orthotitanic acid peptized with 35 wt% hydrochloric acid
% Sol CR seed (manufactured by Teica Co., Ltd.) Titanium sulfate manufactured by Teika Co. is thermally hydrolyzed at 105 ° C., and the resulting orthotitanic acid is mixed with 48 wt% sodium hydroxide and heated to 100 ° C. to form an amorphous material. (Amorphous). Product washed with water and peptized with 35 wt% hydrochloric acid ・ Coagulant of the present invention (Example 1, a product jointly developed by Teica and Daimei Chemical Co.) After neutralization with titanium sulfate, pH: 4.0 Hydrochloric acid concentration: 35 wt%, Colloidal hydrated titanium oxide formed at a temperature of 80 ° C

Example 1 Relationship between hydrolysis pH value and coagulation ability In a 50 L enamel beaker equipped with a paddle-type stirrer, 9 L of 12 wt% sodium hydroxide (ρ = 1.13) was added at room temperature, and then titanium sulfate (Taika Co., Ltd.) TiO ₂ : 250 g / L,
(Total H ₂ SO ₄ : 400 g / L), 10 L are added with stirring. Immediately after completion of the addition, the pH value is adjusted to the value shown in Table 3 with 48 wt% sodium hydroxide or 98 wt% sulfuric acid, and the mixture is further heated at 70 ° C. for 30 minutes, and then washed with filtered water to obtain hydrated titanium oxide. The amount of washing water is twice as much as the cake, and the sulfate content is 2% wt or less. Peptization is TiO ₂
Water and 475 mL were added to adjust the concentration to 5 wt%, and 35% hydrochloric acid and 25 mL to 35 wt% with respect to TiO ₂ were added, followed by treatment at 85 ° C. for 40 minutes.

The obtained colloid solution is BROOKHA
VEN INSTRUMENT B1-90 PAR
The particle size distribution and the average particle size were measured using a TICLE Sizer particle sizer.

Table 3 shows the results of the agglutination test. Table 3 Results of relationship between hydrolysis pH value and aggregation ability (addition amount: 3 ppm as TiO ₂ ) ───── Sample pH average particle size Supernatant turbidity Sedimentation Remarks (nm) (degree) ─────────────────────────── １ 12 <60 nm-× poor hydrolysis 23 〃 1.0 △ 34 △ 0.5 ○ 45 〃 0.7 ○ 56 〃 0.9 △ 67 ７ 1.0 △ 78 〃 2.5 △ 89 〃-× ──────────────────────────────────

As is apparent from Table 3, the coagulation ability of the product of the present invention is excellent in supernatant turbidity and sedimentation when the pH value during hydrolysis is in the range of 3 to 8. When the pH is 2 or less, the hydrolysis is insufficient, and when the pH is 9 or more, the aggregation ability is low.

Example 2 Relationship between Hydrochloric Acid Concentration and Temperature during Peptization and Coagulation Ability A 170 g hydrated titanium oxide cake of Example 1 was slurried with 475 mL of tap water using a 1 L glass beaker equipped with a stirrer. , Concentrated hydrochloric acid and TiO ₂ : 5
wt%, and HCl based on TiO ₂ : 15,25,3
Five samples of 5, 45, 55 wt% were prepared in 0.5 L each. Transfer to a glass three-necked flask and heat up: 60 minutes, aging time: 40 minutes, aging temperature: 70, 80, 90
Peptized at 0 ° C.

Table 1 shows the experimental results. Table 4 Relationship between hydrochloric acid concentration and temperature during peptization and coagulation ability (addition amount: 3 ppm as TiO ₂ ) ────────────────────────── ────── Aging temperature 70 ° C 80 ° C 90 ° C Hydrochloric acid concentration Aggregation ability (wt% to TiO ₂ ) Superficial turbidity Precipitating Superficial turbidity Precipitating Superficial turbidity Precipitating 159.0 × 7 0 × 5.0 × 25 3.5 △ 3.0 △ 2.0 ２351.0 1.0〇0.5〇1.3〇450.8 0.8 ○ 0.7〇3.0 △ 55 △ 7.0 × 6.5 × 9.2 × ─────────────────────────────────

The ripening temperature and the hydrochloric acid concentration at which the optimum flocculating ability was developed were respectively 70 to 90 ° C. and 35 to 45 wt%.

Example 3 Relationship between the amount of added hydrochloric acid and the coagulation ability after aging 170 g of the hydrated titanium oxide cake of Example 1 was slurried with 475 mL of tap water using a 1 L glass beaker equipped with a stirrer. In addition, TiO ₂ was adjusted to 5 wt% and HCl to 35 wt% with respect to TiO ₂ . The mixture was transferred to a glass three-necked flask, heated to 80 ° C. for 60 minutes, aged at this temperature for 40 minutes, and peptized. Each of concentrated hydrochloric acid to the peptized slurry against TiO ₂ 0,50,100,150,200,250,300wt
% Was added.

Table 5 Relationship between the amount of hydrochloric acid added after aging and the coagulation ability (3 ppm as TiO ₂ added)量 Amount of hydrochloric acid added Particle size Aggregation ability (wt.% Vs. TiO ₂ ) (nm) Supernatant turbidity (degree) Precipitation ───────────────── ────────────── 0 1.0 ○ 50 0.4 ○ 100 0.8 １５０ 150 0.7 ２００ 200 1.0 ○ 250 27 × 300 28 × ─────凝集 Addition of 0 to 200 wt% of hydrochloric acid to the deflocculated slurry improves the coagulation ability.

Example 4 Agglomeration ability to Yodogawa raw water Conditions for producing colloidal hydrated titanium oxide Production conditions for hydrated titanium oxide: Same as in Example 1 Neutralization pH: 4.0 Peptization conditions: Examples 2 and 3 Same as above Concentration of hydrochloric acid during aging: 35 wt% Temperature: 80 ° C Hydrochloric acid addition amount: 0 wt%, 50 wt%

Table 6 Aggregation ability for Yodogawa raw water Addition amount (as TiO ₂ ) ─ flocculant 3ppm 5ppm ───────────────────── supernatant turbidity sedimentation supernatant turbidity sedimentation ────────────水 和 Colloidal hydrated titanium oxide 0.3 ○ 0.3 ○ Hydrochloric acid addition amount = 0 wt% Colloidal hydrated titanium oxide 0.3% 4 ○ 0.3 ○ Amount of hydrochloric acid added = 50wt% Aluminum sulfate 0.4 ○ 1.2 △ ────────────────────────────水 和 Colloidal hydrated titanium oxide can replace aluminum sulfate, which is used in large quantities as an inorganic coagulant, both in terms of performance and economy.

Example 5 Relationship between Particle Size and Aggregation Ability in Each Treatment Process Sample: Colloidal hydrated titanium oxide in each process was washed with clean water using Ti
O ₂ = 0.15 wt% adjusted Particle size distribution analyzer: B1-9 manufactured by BROOKHAVEN INSTRUMENT
0 PARTICLE SIZER Measurement of ζ-potential of colloidal hydrated titanium oxide for each treatment step Raw water amount: 500 mL Coagulant addition amount: 10 ppm (as TiO ₂ ) Measuring instrument: laser-zeta-electrometer (Otsuka Electronics) LEZA
Type) Table 7 Relationship between particle size, ζ-potential and coagulation ability by treatment process (addition amount 3ppm as TiO ₂ ) ────────────────────────試 料 Sample size by process ζ-potential turbidity sedimentation (nm) (mV) (degree) ──────────────────── ────────────── Cake + water 233-19.10 30 × cake + water + 35 wt% hydrochloric acid 248.6 △ peptizing ripening solution 54 0.8 ○ peptizing ripening solution + 150 wt% hydrochloric acid 43 +11.720.5 ○ Peptizing ripening solution + 200wt% hydrochloric acid 300.6 ○ Titania sol 64-3.95 20 × CR seed 58-3.96 20 × ──────────────チ Titanyl sulfate 400-700> 30 × ────────────────────── ──コ ロ イ ド The apparent particle size of the colloid particles is reduced by the hydrochloric acid treatment. Further, the hydrochloric acid additive of the colloidal hydrated titanium oxide has a positive potential in raw water.

Example 6 Table 8 Relationship between Raw Water Stirring Conditions and Aggregation Ability Stirring Conditions Rotational Speed (Ppm) Rotation time (min) ──────────────────────────── 1 Rapid stirring 110 10 2 〃 180 53 3 １８０ 180 10 Slow Rapid stirring 40 10 Static -10 ────────────────────────────

The above stirring conditions and aggregating ability were tested to obtain the results shown in Table 9. Table 9 Results of agglutination test (addition amount = 3ppm as TiO ₂ ) ──────────────────────── Stirring conditions Turbidity (degree) Precipitation ── ────────────────────── 1 1.4 △ 2 1.2 △ 3 0.4 ○ ○回 転 The number of revolutions of rapid stirring increases, and the aggregating ability increases as the stirring time increases.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuo Iwane 3-6-1, Hiroruro-cho, Chuo-ku, Osaka-shi, Osaka Inside Teika Co., Ltd. (72) Inventor Hideaki Fujisawa 3585 No. 385 Minamiminowa-mura, Kamiina-gun, Nagano Prefecture Within Chemical Industry Co., Ltd. (72) Inventor Mitaro Tanaka 4- 7-30 Joko Higashi-en, Nishinomiya-shi, Hyogo F-term (reference) 4D015 BA03 BA08 BA10 CA14 DA30 DC03 EA04 EA32 EA35 4D062 BA03 BA08 BA10 CA14 DA30 DC03 EA04 EA32 EA35

Claims (3)

[Claims] 1. A titanium system for water treatment comprising a colloid having an average particle diameter of 20 to 70 nm obtained by hydrolyzing titanium sulfate in an aqueous solution at pH 3 to 8 and peptizing the resulting precipitate of hydrated titanium oxide with hydrochloric acid. Flocculant. (A) a step of adjusting the pH of the aqueous solution of titanium sulfate to 3 to 8 with sodium hydroxide; (b) a step of heating the solution to 60 to 80 ° C. to precipitate hydrated titanium oxide; ) A step of collecting the formed precipitate of hydrated titanium oxide and washing with water until substantially free of sulfate groups; (d) suspending the washed hydrated titanium oxide cake in water again, and adding HCl / TiO ₂ to the suspension. 20 to 45 wt
(E) adding the hydrochloric acid-added suspension to the suspension at 60 to 95 ° C. for 3 hours.
Aging for 0-120 minutes; (f) optionally ₂₀₀ w, expressed as HCl / TiO ₂
The process for producing a flocculant according to claim 1, further comprising the step of adding hydrochloric acid up to t%. 3. A method for purifying water, particularly tap water, wherein the flocculant of claim 1 is added to raw water at ₂ ppm or more as TiO ₂ and stirred, and the generated floc is separated from the supernatant.