JP5733691B2 - Method for continuous recovery of particle components in solution - Google Patents

Description

  The present invention utilizes a phenomenon in which particle components in an aqueous solution aggregate at a liquid-liquid interface formed by an aqueous solution (aqueous phase) in which the particle component as a target substance exists and a solvent (solvent phase) that does not mix with water. The present invention relates to a method for continuously collecting particle components in a solution without using a filter or a centrifuge.

  A filter filtration method is usually used for collecting the particle components in the solution. The filter filtration method has a merit that it can be easily performed by a simple operation, but the filter causes clogging, and is not suitable for continuously treating a solution. In addition, since the filter is usually a consumable item, there are problems of cost and generation of waste. Furthermore, since some of the dissolved components may be adsorbed by the filter, it may not be possible to meet the need to collect only the particle components separately.

Recently, a continuous centrifugation method, which is a filterless technique, is often used as a method for collecting particle components in place of the filter filtration method (see, for example, Patent Document 1). In the continuous centrifugation method, particle components can be collected by continuously treating an aqueous solution. However, an apparatus using a continuous centrifugation method is not inexpensive, has a disadvantage that it has a long processing time and a large running cost, is not compact and lightweight, and does not have a large processing capacity.
JP 09-085120 A

  Although the conventional device using the filterless particle component recovery method (centrifugation method) by centrifugal separation enables continuous particle component recovery, the amount of processing (processing capacity) per unit time is not large. In addition, since a long centrifugal force is required, the running cost is high, and the device itself is not compact and lightweight. That is, its use is limited in terms of cost effectiveness and size / weight. Moreover, even if the particle component can be recovered, the dissolved component cannot be recovered. However, there is a high need to simultaneously collect and remove dissolved components as well as particle components in the solution. For example, it is a case where it is desired to remove all harmful components simultaneously without distinguishing between particle components and dissolved components. On the other hand, there is a need to separately collect dissolved components and particle components simultaneously. For example, from the viewpoint of component separation for the purpose of purification. There is not yet known a method for separating and simultaneously recovering dissolved components and particle components using only one method without combining two or more methods.

  Technology for recovering particulate components in solution has high needs in various industries. One is the need to remove particulate components as harmful substances. Some particle components are harmful to human bodies and living organisms, and such particle components need to be efficiently recovered and removed. Moreover, even if the particle component itself is harmless, it may be harmful by adsorbing harmful substances. On the other hand, there is a need to recover the particle component as a product. Fine particles such as metals and plastics are important as materials for various devices, but since they are often manufactured using reactions in solution, technology is needed to efficiently recover the generated fine particles from the solution. It becomes. Furthermore, the application to the coprecipitation method which is one of the analysis methods of the trace component in a solution can be considered. The coprecipitation method is a method of separating and recovering a trace amount of a target component contained in a solution as a precipitate, but it takes a long time (for example, several days) to sufficiently settle the precipitate. Therefore, there is a need to quickly collect particulate components that are precipitates without waiting for sedimentation.

  An object of the present invention is to provide a method for continuously and rapidly recovering particle components in a solution without using a filter or a centrifuge by utilizing the aggregation phenomenon of the particle components at the liquid-liquid interface. It is in.

  Another object of the present invention is to provide a method for recovering a particle component suspended in an aqueous solution and simultaneously recovering a component (for example, metal ion) dissolved in the aqueous solution by solvent extraction (liquid-liquid extraction). There is.

  A method for continuously recovering particle components in a solution according to one aspect of the present invention includes an aqueous solution at a liquid-liquid interface formed by an aqueous solution (aqueous phase) in which a target particle component is suspended and a solvent (solvent phase) that is not mixed with water. The particle component in the aqueous solution is continuously collected without a filter by utilizing the phenomenon that the particle component in the solution aggregates. In this case, in order to promote the aggregation of the particle component at the liquid-liquid interface, it is preferable that the aqueous phase and the solvent phase are mixed and emulsified (emulsion).

  In the method for continuously recovering particle components in solution according to another aspect of the present invention, the particle component in the aqueous phase aggregates at the liquid-liquid interface, and the dissolved component in the aqueous phase is extracted into the solvent phase through the liquid-liquid interface. It is characterized in that both the particle component and the dissolved component in the aqueous phase are recovered simultaneously using the liquid-liquid extraction phenomenon. In the case of simultaneously recovering dissolved metal ions and the like by using in combination with liquid-liquid extraction, an organic ligand called an extractant may be added to the solvent.

  The apparatus using the method according to the present invention has much higher processing capacity than the conventional continuous centrifugal apparatus, and the running cost, initial cost and maintenance cost are significantly smaller and more compact. . Therefore, utilization in various plants can be expected. In addition, the method of the present invention has a remarkable effect that is not found in the conventional method, in which not only the particle components but also the liquid-liquid extraction method can be used together, so that dissolved components can be recovered at the same time.

  The method for continuously recovering particle components in solution according to the present invention will be described in detail below with reference to the drawings. First, refer to FIG. 1 and FIG. FIG. 1 shows an example of the aggregation phenomenon of particle components at the liquid-liquid interface, which is the principle of the present invention. FIG. 2 shows an example of a specific apparatus for carrying out the continuous recovery method for particle components in a solution according to the present invention.

Please refer to FIG. Prepare a suspended aqueous solution containing a large amount of iron oxide Fe ₂ O ₃ as a particle component in a test tube (see Fig. 1 (a)), and then gently add isooctane (see Fig. 1 (b)). The sample was shaken by hand for 10 seconds and allowed to stand for 1 minute (see FIG. 1C). Through this series of operations, iron oxide Fe ₂ O ₃ aggregated at the liquid-liquid interface, and the suspended aqueous solution was purified. At this time, the aggregation of the particle component at the liquid-liquid interface can be promoted by mixing the aqueous phase and the solvent phase into an emulsion (emulsion).

Next, based on FIG. 2, the continuous collection method of the particle | grain component in a solution which concerns on this invention is demonstrated concretely. The emulsion flow apparatus 10 shown in FIG. 2 includes a first head part 11 for ejecting an aqueous phase, a second head part 12 for ejecting a solvent phase, a column part 13 for generating an emulsion flow, and above and below the column part. It is composed of an apparatus main body composed of the installed phase separation units (upper phase separation unit 14 and lower phase separation unit 15) and a liquid feed pump 16 (one duplex unit or two single units). The head portions (11, 12) are not necessarily in contact with the liquid phase (aqueous phase, solvent phase, or emulsion mixed phase). A water sample in the reservoir 20 is sent to the emulsion flow device 10 via a conduit 21. The first head portion 11 is a cylinder whose both ends are open, a cylinder whose one end is covered with a 1 μm to 5 mm mesh or a sheet having a hole, a cylinder which is closed at one end, its closed part or its periphery. A structure in which an appropriate number of holes having a diameter of 1 μm to 5 mm are formed in both of the parts, or a structure in which the perforated cylinder is further covered with a sheet having a hole of 1 μm to 1 mm or a hole, or 10 μm to 1 mm. It has a structure in which a porous body (for example, sintered glass) having a pore size is bonded to a cylinder. The second head unit 12 has a structure similar to that of the first head unit 11, but the size of the hole or mesh of the second head unit 12 is the size of the hole or mesh of the first head unit 11. It may be different from the size. In the upper phase separation unit 14 and the lower phase separation unit 15, phase separation is performed by utilizing a sudden volume increase in a portion through which the emulsion flow passes, but the container need not necessarily be a container having a larger diameter than the column 13. A container having a smaller volume than the column part 13 and having a narrow mouth may be inserted into the part 13.

  Next, the operation of the apparatus shown in FIG. 2 will be described. The water sample from the reservoir 20 is supplied to the first head portion 11 of the emulsion flow apparatus 10 by a liquid feed pump 16 provided in a conduit 21 that connects the reservoir 20 of the water sample containing the particle component and the emulsion flow apparatus 10. It is ejected through the cylinder and into the solvent phase. At the same time, droplets in which the solvent phase is refined are ejected so as to face the flow of the aqueous phase through the cylinder which is the second head portion 12 of the emulsion flow apparatus 10. Thereby, in the column part 13 of the emulsion flow apparatus 10, the flow (it calls an emulsion flow) which consists of a mixed phase (emulsion mixed phase) of a water phase and a solvent phase generate | occur | produces. When the emulsion mixed phase reaches the phase separation section (14, 15) of the emulsion flow apparatus 10, the state of the emulsion flow is released and the phase is separated into an aqueous phase and a solvent phase. A solvent phase collects in the upper phase separation unit 14, and an aqueous phase collects in the lower phase separation unit 15. The clean solvent phase in the upper phase separation unit 14 is circulated through the second head unit 12. Moreover, the clean aqueous phase in the lower phase separation part 15 is taken out as waste water after processing. The cylinder of the head part (11, 12) is not necessarily a cylinder, and may be a square cylinder, for example. Further, the shapes of the column portion 13 and the phase separation portions 14 and 15 are not necessarily cylindrical, and may be, for example, a quadrangular prism shape.

  As the emulsion flow occurs in the column part 13, the particle component 31 in the water sample comes to adhere to the inner wall of the column part 13. The particle component that has aggregated at the liquid-liquid interface whose area has been remarkably increased by emulsification stays inside the emulsion flow, which is an emulsion mixed phase, without transferring to either the aqueous phase or the solvent phase. This is because it adheres to the vessel wall after repeated circulation. The particle component 31 adhering to the inner wall of the column part can be recovered using, for example, a piston 30 as shown in FIG.

Specific examples are shown below. The small and medium-sized emulsion flow devices shown in FIGS. 3 and 4 (both 70 cm in height) were manufactured, and the experiment for collecting only the particle component and the experiment for simultaneously collecting the particle component and the dissolved component were conducted. While performing performance evaluation, it compared with the result by the conventional method (continuous centrifugation method). As the particle component, aluminum oxide Al ₂ O ₃ particles classified into a particle diameter of 20 μm to 25 μm were used, and ytterbium Yb (trivalent ion) was used as the dissolved component. In addition, this invention is not restrict | limited at all by these Examples.

In the examples shown below, particles that can be recovered by using aluminum oxide Al ₂ O ₃ particles that have been sized by classification and collecting and measuring the weight of particles remaining in the aqueous phase after treatment by filtration. The ratio (recovery rate) was determined. The particle classification method and how to obtain the recovery rate are shown below.
<Aluminum oxide Al ₂ O ₃ particle classification method>

Commercially available aluminum oxide Al ₂ O ₃ was classified in the following manner.
1) Aluminum oxide Al ₂ O ₃ was dried overnight in a desiccator containing phosphorus pentoxide.
2) Classification was performed using two types of stainless steel sieves (20 μm and 25 μm).
First, particles having a size of 25 μm or more were removed using a 25 μm sieve (collecting particles that passed through the sieve).
-Furthermore, particles having a size of 20 μm or less were removed using a 20 μm sieve (collecting the particles remaining on the sieve). Therefore, the aluminum oxide Al ₂ O ₃ particles were classified only to a size of 20 μm or more and 25 μm or less.
<How to find the recovery rate of aluminum oxide Al ₂ O ₃ particles>

Aluminum oxide Al ₂ O ₃ particles not recovered by the apparatus and remaining in the aqueous phase were measured by a filtration method. As the filter, a polycarbonate filter (0.2 μm) having no weight change due to water contact was used.
1) The empty weight of the filter was measured.
2) Aluminum oxide Al ₂ O ₃ particles contained in _{2 to 3} L of aqueous phase were separated by a filter.
3) The filter was dried for about 1 day in a desiccator containing silica gel.
4) The filter weight was measured, and the difference from the empty weight was taken as the weight of the remaining aluminum oxide Al ₂ O ₃ particles. Assuming that the Al ₂ O ₃ concentration (calculated from the amount added) in the untreated solution is a (mg / L) and the remaining Al ₂ O ₃ concentration is b (mg / L), the recovery rate = (ab) / a × 100 (%).

  Experiments on recovery of particulate components in aqueous solution using a small device

Please refer to FIG. Using a small emulsion flow apparatus 10a (apparatus volume = 3 L, apparatus weight = 2 kg), an experiment was conducted to recover aluminum oxide Al ₂ O ₃ particles. Specifically, we prepared a 20 L nitric acid aqueous solution (pH 2) mixed with 0.02 M aluminum oxide Al ₂ O ₃ particles (particle size 20 μm to 25 μm), and used a small emulsion flow with 1 L isooctane arranged. Then, a recovery experiment of the particle component was conducted. FIG. 3 (a) is a photograph of the small emulsion flow apparatus used at this time. The first head portion 11 of this apparatus has a structure in which ten holes with a diameter of 1 mm are formed around a polypropylene tube with one end closed, and the second head portion 12 is a sintered glass plate having a hole diameter of 40 μm. The structure is bonded to a cylinder. In addition, a container with a narrow mouth was inserted above the column unit 13 and used as the upper phase separation unit 14 so as to reliably deliver a clean solvent phase while avoiding the emulsion (FIG. 3 (b). )). As the lower phase separation part 15, a container having a diameter larger than that of the column part 13 was used by being coupled to the lower part of the column part 13.

In order to treat 20 L of nitric acid aqueous solution containing aluminum oxide Al ₂ O ₃ as a particle component using the above small emulsion flow device, the flow rate of the aqueous phase to be sent is 20 L / hour, and the flow rate of the solvent phase to be circulated is When set to 20 L / hour, the processing time required 60 minutes (processing capacity of 20 L / hour), almost 100% (99.5% or more: the decimal point is not accurate from the point of measurement error) Al ₂ Al ₂ O ₃ particles could be recovered.

  Experiments on recovery of particulate components in aqueous solution using medium-sized equipment

Please refer to FIG. FIG. 4 shows a medium emulsion flow apparatus 10b. The medium-sized device referred to here means a device whose device volume is about three times that of the device shown in (Example 1). In this experiment, the medium emulsion flow apparatus (apparatus volume = 9 L, apparatus weight = 4 kg) shown in FIG. 4 (a) was used. The first head portion 11 of this apparatus has a structure in which six holes with a diameter of 4.8 mm are formed around a polypropylene tube with one end closed, and the second head portion 12 is a sintered glass plate having a hole diameter of 40 μm. The structure is bonded to a cylinder. In addition, a container with a narrow mouth was inserted above the column unit 13 and used as the upper phase separation unit 14 so that a clean solvent phase could be reliably delivered while avoiding the emulsion (FIG. 4B). )). As the lower phase separation part 15, a container having a diameter larger than that of the column part 13 was used by being coupled to the lower part of the column part 13. This apparatus was found to have a processing capacity approximately 10 times that used in (Example 1).

Prepare a 200 L aqueous nitric acid solution (pH 2) mixed with 0.02 M aluminum oxide Al ₂ O ₃ particles (particle size 20 μm to 25 μm), and use a medium emulsion flow device with 2 L isooctane in place. A component recovery experiment was conducted. The flow rate of the aqueous phase to be sent was set to 228 L / hour, the flow rate of the solvent phase to be circulated was set to 30 L / hour, and the treatment of the 200 L aqueous solution was completed in 53 minutes (processing capacity of 228 L / hour). As a result, almost 100% of the aluminum oxide Al ₂ O ₃ particles were recovered as in (Example 1). That is, even when the treatment capacity of the solution was significantly increased from 20 L / hour (Example 1) to 228 L / hour (Example 2), there was almost no change in the recovery rate of aluminum oxide Al ₂ O ₃ . From the above, it was found that the emulsion flow apparatus can be easily enlarged while maintaining its performance.

It has also been found that the size of the hole formed in the head part (first head part 11) for ejecting the aqueous phase is not so important. That is, it was found that a solution containing a particle component having a large size can be processed without causing clogging if the hole of the first head portion 11 is enlarged. In addition, since the particle | grain component in an aqueous phase was not distributed at all to a solvent phase, it turned out that the 2nd head part 12 does not have worry about clogging.
(Comparative Example 1) Comparison with continuous centrifugation

Using a commercially available apparatus (H-660 type continuous centrifuge manufactured by Kokusan Co., Ltd.), an experiment was conducted to recover the classified aluminum oxide Al ₂ O ₃ particles used in the above examples from an aqueous solution. The rotor speed at this time was 15,000 rpm, and when the aqueous suspension was treated at 23 L / hour, almost 100% of aluminum oxide Al ₂ O ₃ particles (99.5% or more: from the point of measurement miscalculation, the decimal point is not accurate. Not) It took 52 minutes to process the 20 L suspension (23 L / hour throughput). The size of the H-660 type continuous centrifuge is 650 (width) × 650 (depth) × 870 (height) mm, the apparatus volume is 368 L, and the weight is 160 kg.

  Experiments on simultaneous recovery of particulate and dissolved components in aqueous solution

In (Example 1) and (Example 2), pure isooctane was used as a solvent phase, but by adding an appropriate extractant thereto, dissolved metal ions can be recovered together with the particle components in a fractional manner. Can do. In (Example 3), 0.02 M aluminum oxide Al ₂ O ₃ as a particle component and 10 L of nitric acid aqueous solution at pH 2 containing 6 × 10 ⁻⁶ M ytterbium Yb (trivalent ion) as a dissolved component are 10 The experiment was conducted using the above medium emulsion flow apparatus in which 2 L of isooctane containing mM bis (2-ethylhexyl) phosphate: DEHPA (extractant) was placed. As a result, almost 100% of the aluminum oxide Al ₂ O ₃ as a particle component and about 98% of ytterbium Yb as a dissolved component could be recovered separately. In this experiment as well, using the medium-sized device shown in Fig. 4 (a), the flow rate of the water phase to be sent was set to 231 L / h, the flow rate of the solvent phase to be circulated was set to 30 L / h, and 200 L of aqueous solution was treated. Finished in 52 minutes (231 L / hour processing capacity). FIG. 5 is a photograph of the state of aluminum oxide Al ₂ O ₃ particles adhering in large quantities to the column part after performing the recovery operation in this example.

  The particle collection performance of the emulsion flow apparatus used in the present invention is almost the same as that of a continuous centrifuge. In addition, since there is no power unit that requires a large number of heavy metal parts, the emulsion flow apparatus is lightweight and does not have a restriction that a solution containing an acid cannot be handled. Furthermore, in the method of the present invention, a solvent that does not mix with water such as alkane (for example, kerosene) is used as the solvent. Therefore, in combination with the liquid-liquid extraction method, dissolved components dissolved in the solution can be simultaneously dissolved. It can be collected and removed. In the case of simultaneously recovering the dissolved components together with the particle components, an extractant may be added to the solvent alkane. However, by using an extractant that has low solubility in water and easily decomposes in the environment, Can be a small method.

  The apparatus using the method according to the present invention can recover and remove particulate components in a solution continuously and without a filter, and does not need to apply mechanical external force such as centrifugal force. Running cost is small. In addition, the simple structure makes it easy to handle, has low initial costs, low maintenance costs, and is compact. For example, in comparison with a commercially available device using a conventional continuous centrifugation method (for example, Hoku-C type H-660 continuous centrifuge manufactured by Kokusan Co., Ltd.), the emulsion flow device has about 1/40 of the volume and weight of the device. It has a processing capacity of about 10 times, and conversely, the running cost, initial cost and maintenance cost are all estimated to be 1/10 or less (see Example 2 and Comparative Example 1).

  As described above, this method is excellent in all aspects such as cost-effectiveness, performance and ease of handling, compactness, and consideration for the environment, and can be expected to be used in various industries. For example, recovery / removal technology for harmful particulate components contained in factory wastewater, etc., or particulate components that are harmful by adsorbing harmful substances, and water purification technology that simultaneously removes harmful dissolved components together with particulate components, It can be a revolutionary low-cost technology that has never been seen before in various applications, such as the recovery of fine particle materials produced using in-solution reactions and the rapid coprecipitation method used in the analysis of trace components. In addition, the utility value as environmental purification technology can be greatly expected.

Is a photograph for explaining the agglomeration of the liquid-liquid interface of the iron oxide Fe ₂ O ₃ particles. It is the schematic which shows an example of the apparatus for enforcing the continuous collection method of the particle | grain component in a solution of this invention. It is a whole block diagram which shows the small experimental instrument of the emulsion flow apparatus used with the apparatus shown by FIG. It is a whole block diagram which shows the medium-sized laboratory instrument of the emulsion flow apparatus used with the apparatus shown by FIG. Is a diagram showing a state of aluminum oxide Al ₂ O ₃ deposited on a column of laboratory instruments emulsion flow apparatus used in the apparatus shown in FIG.

Explanation of symbols

10: Emulsion flow device 11: First head part 12: Second head part 13: Column part 14: Upper phase separation part 15: Lower phase separation part 16: Liquid feed pump 20: Reservoir 21: Conduit 30: Suspended particle trapping Piston 31 for collecting: Adhering suspended particles

Claims (2)

A method of continuously recovering particle components in a solution using an emulsion flow apparatus provided with a column part where an emulsion flow occurs and a phase separation part installed above and below the column part,
An aqueous phase, which is an aqueous solution containing a particle component, is ejected into the column part, and at the same time as the ejection of the aqueous phase, droplets obtained by refining a solvent phase that does not mix with water face the ejection of the aqueous phase. Generating an emulsion flow consisting of a mixed phase of the aqueous phase and the solvent phase in the column portion by jetting into the column portion;
When the emulsion flow reaches the phase separation part from the column part, the state of the emulsion flow is released, and the water phase and the solvent phase are phase-separated; A method for continuously recovering particle components in solution, comprising the step of recovering the particle components in the aqueous solution aggregated at the liquid-liquid interface formed by the phase and the solvent phase. The method according to claim 1, wherein the particle component in the aqueous solution is recovered by spraying into the column portion so as to face the spray of the aqueous phase while circulating the solvent phase after phase separation. A method for continuously recovering particle components in a solution.

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