JP2018035427A - Manufacturing method of platinum nanocolloid, single nano platinum colloid solution narrow in particle size distribution and high in stability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a platinum nanocolloid solution having no aggregate for long time.SOLUTION: There are provided a manufacturing method of a platinum nanocolloidal solution containing 100% of the platinum nanocolloid solution in a range of particle diameter of 4.1 nm±1.9 nm, regardless of high concentration even after 4 or more months or 10 or more months have passed after manufacturing at a particle size distribution measurement point, and the platinum nanocolloidal solution capable of keeping a transparent state over 1 year or more and having easiness of storage control without aggregation and deposition for long time when manufactured by the manufacturing method.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a single platinum nanocolloid aqueous solution having a narrow particle size distribution width.

  In order to prevent agglomeration of platinum colloid, a protective agent is generally used. However, in JP 2009-228067 A, the pH of an aqueous solution is adjusted to 7.0 to 8.5 without a protective agent such as a surfactant. However, a method for producing a platinum colloid that does not aggregate for more than one month by adjusting the production conditions of electrical conductivity is shown. JP 2011-195931 discloses a platinum nanoparticle aqueous solution, a platinum nanoparticle carrier, and a method for producing the same, which can be stably dispersed without aggregation of platinum nanoparticles. The period of not aggregating is not specifically shown. Japanese Patent Application Laid-Open No. 2002-285207 discloses that a platinum support obtained using a platinum colloid aqueous solution can be used for various applications such as a redox catalyst. As a use of platinum nanocolloid, there are many products that are expected to have health and beauty effects, but no disclosure of a method for producing an aqueous solution of platinum nanocolloid that can be stored without agglomeration for a long period of time has been found. In the case of gold colloid, it is described in Non-Patent Document 1 that gold colloid synthesized by Thomas Graham is still stored at the British National Laboratory even after 150 years.

  However, when the platinum nanocolloid does not contain a protective agent, the platinum nanocolloid aqueous solution that has been agglomerated and aggregated by repeating the collision of the nanoparticles due to Brownian motion, and has been aggregated and precipitated once. However, since it is difficult to return to the nanocolloid state, and platinum is an expensive noble metal in itself, there is a problem that precautions are required in the storage management of the platinum nanocolloid aqueous solution.

  In addition, even if you purchase a platinum nanocolloid aqueous solution, strict storage and management are necessary so that it does not agglomerate, and the running cost increases due to the inability to stock for a long period, such as the need to keep the expiration date after opening There was a problem such as.

  Various methods for stabilizing nanocolloids have been developed as measures to improve this, but methods that prevent aggregation by charging the surface of the nanocolloid in solution and methods that prevent aggregation using additives such as surfactants are generally used. Is. However, depending on the type of additive, there are cases where the resulting colloidal characteristics are greatly affected, and there is a problem that attention is required for its use.

JP2011-195931A JP 2009-228067 A JP 2002-285207 A JP-A-57-149801

"Nano colloid synthesis, physical properties, and functions" edited by Toshiharu Teranishi, Tsukasa Shimamoto and Mami Yamada, published by Modern Science Co., Ltd.

  The problem to be solved is to develop platinum nanocolloids that improve from the manufacturing process and do not aggregate for a long time.

In the present invention, hydrogen peroxide [H ₂ O ₂ ] is added to an aqueous solution mainly composed of hexachloroplatinic acid hexahydrate [H ₂ Cl ₆ Pt · 6H ₂ O], which is one type of chloroplatinic acid, The main feature is that it is a platinum nanocolloid aqueous solution manufactured by adding an organic reducing agent in the final step while performing temperature control and aqueous solution color control.

  The platinum nanocolloid aqueous solution of the present invention can be used in the follow-up observation and particle size distribution measurement at room temperature for a long period of more than six months or one year at the time of specification preparation. There is an advantage that it can be stored for a long time because it does not aggregate and no sediment is seen. Furthermore, the platinum nanocolloid aqueous solution of the present invention can be used for various applications by using sugar alcohol, which is a naturally derived food additive, and has an advantage that it is particularly suitable for applications that touch the human body. .

FIG. 1 is a photograph of the aqueous platinum nanocolloid solution of the present invention. FIG. 2 is a graph obtained by measuring the particle size distribution of the platinum nanocolloid aqueous solution 1 (500 ppm) of the present invention after 10 months at the time of measuring the particle size distribution. FIG. 3 is a graph obtained by measuring the particle size distribution of the platinum nanocolloid aqueous solution 2 (500 ppm) of the present invention after 4 months at the time of measuring the particle size distribution. FIG. 4 is a sample photograph used for a comparative test of formaldehyde decomposition performance of a commercially available tungsten trioxide aqueous solution having visible light response characteristics and a tungsten trioxide aqueous solution to which the platinum nanocolloid aqueous solution of the present invention is added. Example 1 For comparison, it is a photograph at the start when 0.5 g of hexachloroplatinic acid hexahydrate and 500 ml of water without adding hydrogen peroxide and stirring with a magnetic star are added. It is the photograph of the aqueous solution after progress for 15 minutes after the start of stirring of the aqueous solution of FIG. It is the photograph of the aqueous solution after 30-minute progress after the stirring start of the aqueous solution of FIG. 6 is a photograph of the aqueous solution after 45 minutes from the start of stirring of the aqueous solution in FIG. 5.

(Manufacturing method 1)
The first step of hexachloroplatinic acid hexahydrate _{[H 2} PtCl ₆ · 6H 2 O] 0.5g of water _{[H 2} O] 500 ml (= 1000 ppm) was placed in a beaker and stirred with a magnetic hot stirrer, peroxide An aqueous solution is made by adding 20 ml of a 3% solution of hydrogen (H ₂ O ₂ ).
It was heated increase the temperature of the aqueous solution of the second step 20 ° C. to 25 ° C. to 80 ° C. to 90 ° C., further added 200ml of water _{[H 2} O].
A third step of trisodium citrate _{[C 6 H 5 Na 3 O 7} · 2H 2 O ] 1% solution was added 50 ml, once to adjust the temperature of the aqueous solution to the current temperature 65 ° C. to 70 ° C..
Step 4 Heating and maintaining the temperature at 95 ° C. to 98 ° C. (boiling state) for about 10 minutes while stirring while observing the color of the aqueous solution, the yellow aqueous solution suddenly changed to a reddish golden color After confirming this, 260 ml of water [H ₂ O] is added, and the temperature of the aqueous solution is adjusted to 65 ° C to 70 ° C.
5th step 40 ml of 1% sugar alcohol solution is added, and the temperature of the aqueous solution is lowered by natural cooling.
Step 6 Stirring is continued for an additional 1-2 hours for the purpose of removing excess oxygen in the remaining hydrogen peroxide [H ₂ O ₂ ].

In the third step, trisodium citrate is preferred, but organic reducing agents of C _{4 to} C ₆ such as polyvinylpyrrolidone (C ₄ H ₇ ON) and sodium ascorbate (C ₆ H ₇ NaO ₆ ) are also the same. Can be used.

Among the sugar alcohols used in the fifth step, pentitol [C ₅ H ₇ (OH) ₅ ] and hexitol [C ₆ H ₈ (OH) ₆ ] are particularly prominent, among which mannitol and sorbitol. Galactitol is suitable. Instead of using various surfactants for the stabilization treatment that does not aggregate and settle for a long time so as not to lead to particle growth from collision due to Brownian motion of nanoparticles, instead of using various surfactants, the aqueous solution of platinum nanocolloid of the present invention is used. Is suitable for various uses by using naturally derived sugar alcohols.

(Manufacturing method 2)
The first step of hexachloroplatinic acid hexahydrate _{[H 2} PtCl ₆ · 6H 2 O] 0.1g of water _{[H 2} O] 100 ml (= 1000 ppm) was placed in a beaker and stirred with a magnetic hot stirrer, peroxide An aqueous solution is made with 10 ml of a 2% solution of hydrogen (H ₂ O ₂ ).
Was heated increase the temperature of the aqueous solution of the second step 20 ° C. to 25 ° C. to 80 ° C. to 90 ° C., further added 80ml of water _{[H 2} O].
Third step 20 ml of 1% aqueous solution of ascorbic acid [C ₆ H ₈ O ₆ ] is added, and the temperature of the aqueous solution is once adjusted to a current temperature of 65 ° C to 70 ° C.
Step 4 Heating and maintaining the temperature at 95 ° C. to 98 ° C. (boiling state) for about 10 minutes while stirring while observing the color of the aqueous solution, the yellow aqueous solution suddenly changed to a reddish golden color After confirming this, 50 ml of water [H ₂ O] is added, and the temperature of the aqueous solution is adjusted to 65 ° C to 70 ° C.
Fifth Step If the stirring is continued for 1 to 2 hours for the purpose of removing excess oxygen in the remaining hydrogen peroxide [H ₂ O ₂ ], 250 ml of a platinum nanocolloid aqueous solution having a concentration of 400 ppm can be produced. The pH value of the aqueous solution is about 3.5.

In the third step of the production method 2 described above, instead of ascorbic acid, 20 ml of a 1% aqueous solution of malic acid (C ₄ H ₆ O ₅ ) that is a C _{4 to} C ₆ fruit acid, citric acid (C ₆ H ₈ O ₇ ) Even when 20 ml of 1% aqueous solution or 30 ml of polyvinylpyrrolidone (C ₄ H ₇ ON) as an organic reducing agent is used, a 400 ppm platinum nanocolloid aqueous solution having a pH value of 3.5 to 4.0 Can be manufactured.

Like the production method 2, a desired effect may be obtained even if the step of stabilizing the platinum nanocolloid aqueous solution with sugar alcohol is not inserted between the fourth step and the fifth step. In order to prevent agglomeration and sedimentation for a long period of time even from preventing collision due to collision, the pentitol [C ₅ H] is particularly used as a sugar alcohol for the nano-state stabilization treatment of the aqueous solution. ₇ (OH) ₅ ] and hexitol [C ₆ H ₈ (OH) ₆ ] are effective, but among them, mannitol, sorbitol, and galactitol are preferably added.

(Particle size distribution)
FIG. 1 is a photograph of an aqueous solution of platinum nanocolloid used for particle size distribution measurement. In the container, the actual color is a golden transparent liquid. The platinum nanocolloid aqueous solution 1 in the right container in FIG. 1 was manufactured on July 27, 2015, and the platinum nanocolloid aqueous solution 2 in the left container was manufactured on January 26, 2016. It is a thing. The particle size distribution was measured by using a dynamic light scattering (DLS) particle size distribution measuring device manufactured by Microtrack Bell Co., Ltd. Since the particle size distribution measurement was on May 24, 2016, FIG. 2 is a graph showing the particle size distribution of the aqueous platinum nanocolloid solution 1 (500 ppm) of the present invention that has already passed 10 months at the time of particle size measurement. FIG. 3 shows the particle size distribution of the aqueous platinum nanocolloid solution 2 (500 ppm) of the present invention that has already passed 4 months at the time of particle size measurement.

  From FIG. 2, the platinum nanocolloid aqueous solution 1 of the present invention has no aggregation / sedimentation even though 10 months have passed, and the particle diameter is 100% within the range of 4.1 nm ± 1.9 nm. FIG. 3 shows that the platinum nanocolloid aqueous solution 2 of the present invention has no agglomeration / sedimentation and the particle size is 4.2 nm ± 2.2 nm even though 4 months have passed. It is shown that it is included in the range of 100%.

In order to investigate the ease of aggregation of the aqueous solution of hexachloroplatinic acid hexahydrate without adding hydrogen peroxide, 0.5 g of hexachloroplatinic acid hexahydrate and 500 ml of water were added and stirred with a magnetic stirrer 7 FIGS. 5 to 8 show photographs substituted for drawings of the state changes. FIG. 5 is a photograph immediately after the start of stirring, FIG. 6 is a photograph of 15 minutes after the start of stirring, FIG. 7 is a photograph of 30 minutes after the start of stirring, and FIG. 8 is a photograph of 45 minutes after the start of stirring. It is.
The aqueous solution of FIG. 5 is almost transparent, but in FIG. 6 at the time when 15 minutes passed, it had the same degree of transparency as the platinum nanocolloid aqueous solution of the present invention. Then, in FIG. 8 when 45 minutes have passed since the aggregation started, it can be seen that the aqueous solution is in a black opaque state and the aqueous solution of hexachloroplatinic acid hexahydrate tends to aggregate.

Add 20 ml of the platinum nanocolloid aqueous solution (500 ppm) of the present invention to 230 ml of a commercially available tungsten trioxide aqueous solution (concentration 0.1 wt%) and 230 ml of the commercially available tungsten trioxide aqueous solution (concentration 0.1 wt%). Two types of aqueous solutions adjusted to 250 ml were prepared and a formaldehyde removal performance comparison test was conducted. As shown in FIG. 4, sample 1 and sample 2 were prepared in which an amount of about 20 g / m ² was evenly applied with a sponge to one side surface of a commercial wallpaper (no photocatalytic function) 10 cm long × 10 cm wide × 1 mm thick. . Sample 1 is a wallpaper sample obtained by applying a commercially available tungsten trioxide aqueous solution, and sample 2 is a wallpaper sample obtained by applying an aqueous solution obtained by adding the platinum nanocolloid aqueous solution of the present invention to a commercially available tungsten trioxide aqueous solution. Put each sample in a 5 liter Tedlar bag (Omi Odo Air Service Co., Ltd.), inject 3 liters of formaldehyde gas, which is the measurement target gas adjusted to an initial concentration of 40 ppm, and fluorescent light (1000 lux [lx]) After standing still under irradiation, the initial concentration, the formaldehyde concentration after 2, 4 and 6 hours were measured with a detector tube. The gas detector tube used was manufactured by Gastec Co., Ltd., and the detector tube number 91L was used, and a short formaldehyde detector tube was used.

  Table 1 shows the formaldehyde removal performance test of Sample 1 and Sample 2. In order to examine the effect of adsorption on a Tedlar bag or the like, a blank (blank test) was also performed to measure the formaldehyde concentration. From this result, in the case of only commercially available tungsten trioxide of sample 1, the formaldehyde concentration after 2 hours is 6.2 ppm, and after 4 hours and 6 hours, it becomes 5 ppm or less near the detection limit of the detector tube. On the other hand, the sample 2 to which the platinum nanocolloid aqueous solution of the present invention was added became 5 ppm or less near the detection limit of the detector tube after 2 hours, and the formaldehyde removal performance was only the tungsten trioxide aqueous solution. It can be seen that the comparison is improved. In addition, the formaldehyde concentration in the blank (blank test) is not substantially changed, and it is considered that there is no adsorption to the Tedlar bag, etc. The numerical values in Table 1 indicate the formaldehyde removal performance of Sample 1 and Sample 2 by the visible light activity. It is thought that.

  Hexachloroplatinic acid hexahydrate, which is a raw material for the aqueous platinum nanocolloid solution of the present invention, is 3 to 4 times more expensive than the price of platinum itself of 4,004 yen / g (as of August 16, 2016). When a platinum nanocolloid aqueous solution is produced from the raw material, if the nanocolloid state can be maintained without agglomerating for a long period of time, it can greatly contribute to the reduction of maintenance costs. The platinum nanocolloid aqueous solution of the present invention uses a product that has passed from 4 months to 10 months from its production at the time of particle size distribution measurement, and 12 months from its production at the time of the patent application, but sediment is observed. In other words, a transparent aqueous solution is maintained. Further, as shown in Example 1, it can be considered that if it is used as a modifying substance for the visible light active photocatalyst, it can contribute to the improvement of visible light activity characteristics.

  Deodorant and antibacterial functions include pet odor, nonenal, indoor cigarette odor, sock and underwear odor, toilet, closet, clog box odor, bedding, deutan odor, antibacterial, allergic mold It can be expected to be applied to the decomposition and removal of allergens such as mites, mites and pollen, and the sterilization of Escherichia coli, Staphylococcus aureus, O-157, avian influenza, thers, norovirus, and other bacteria. Furthermore, the modification to titanium oxide or tungsten oxide can be applied to the antifouling of the outer wall of the building and the decomposition and removal of harmful gases such as formaldehyde and acetaldehyde in the room. In addition, even when stored at room temperature, it can maintain a nanocolloidal state that does not aggregate or settle for a long period of time, so it can be immediately provided as an aqueous solution of platinum nanocolloid when needed for construction, which is highly cost-effective It can be said.

1 Platinum nanocolloid aqueous solution manufactured on July 27, 2015 2 Platinum nanocolloid aqueous solution manufactured on January 26, 2016 3 Wall paper coated only with a commercially available tungsten trioxide aqueous solution (Sample 1)
4 Wall paper coated with an aqueous solution of platinum nanocolloid solution of the present invention added to a commercially available tungsten trioxide aqueous solution (Sample 2)
5 Beaker 6 Thermometer 7 Magnet Hot Stirrer 8 Rotor 9 Glass Plate

Claims (6)

A method for producing an aqueous platinum nanocolloid solution in which chloroplatinic acid is reduced with a C _{4 to} C ₆ fruit acid or an organic reducing agent exhibiting C _{4 to} C ₆ reducing properties while adjusting the temperature in the presence of hydrogen peroxide. Chloroplatinic acid in the presence of hydrogen peroxide, while adjusting the temperature, is reduced with an organic reducing agent indicating reduction of fruit acids or C ₄ -C ₆ of C ₄ -C _6, treating stabilized with a sugar alcohol A method for producing an aqueous platinum nanocolloid solution. The method for producing an aqueous platinum nanocolloid solution according to claim 1 or 2, wherein the C _{4 to} C ₆ fruit acid is malic acid, ascorbic acid or citric acid. The method for producing an aqueous platinum nanocolloid solution according to claim 1 or 2, wherein the C _{4 to} C ₆ organic reducing agent is trisodium citrate, polyvinylpyrrolidone or sodium ascorbate. The range of the particle size distribution after the lapse of 10 months or more after the production is in the vicinity of the particle size of 4.0 ± 2.0 nm, and no sedimentation / aggregation is observed. Platinum nanocolloid aqueous solution. The platinum nanocolloid aqueous solution according to claim 5, which is added to a photocatalyst to improve visible light activity.