Particles for incorporating perfluorinated surfactants

Abstract

The present invention relates to the preparation of adsorbent resins for binding perfluorinated surfactants, wherein the method comprises a pure external coating of a commercial ion exchanger or a complete coating of porous polymer particles with an amino-containing polymer, followed by modification of the polymer with a functionalized ligand.

Description

[0001] This application is a divisional application of the invention patent application with application date of March 13, 2020, application number 202080020770.6, and invention name “Particles with biocidal coating”. Technical Field

[0002] The present invention relates to the preparation of adsorbent resins for incorporating perfluorinated surfactants, wherein the process comprises the pure external coating of commercial ion exchangers or the complete coating of porous polymer particles with amino group-containing polymers and subsequent modification of the polymers with functionalized ligands. Background Art

[0003] According to a report from the World Economic Forum (2015), water crisis is defined as the number one global risk that will affect the entire global population.

[0004] The World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) also highlight that 663 million people in the world currently lack access to clean drinking water, and 2.4 billion people use water sources of insufficient quality (as of 2015).

[0005] The overall situation has several causes, among which the continued population growth, the reduction of water sources due to climate change and global warming and the increasing contamination of water sources by industrial waste may be mentioned here. Therefore, improving the quality of drinking water and reducing water pollution are of decisive importance.

[0006] Drinking water sources can be contaminated with a variety of pollutants. These include chemicals, bacteria, micropollutants and heavy metals. For health reasons, these contaminants must be removed from the water before drinking.

[0007] In order to obtain safe and clean drinking water, there are several possible methods for removing contaminants. The most common technology is mechanical filtration, which is achieved using different technologies and processes. The contaminants must be filtered with the help of filters, membranes, etc. with a defined pore size smaller than the contaminants.

[0008] Reverse osmosis is one of these filtration methods where a large portion of the water to be filtered is discarded as waste (approximately 90%), with high operating costs (e.g., electricity requirements). Given the depletion of water resources in today's world, it is important to develop cost-effective and water-saving drinking water filtration technologies.

[0009] It is now obvious that none of the technologies available on the market can cover all areas of the possible range of pollutants alone. This also applies to the resins supplied by instrAction GmbH, which for example cannot remove "chlorine" from water. Therefore, an intelligent and novel combination of known purification technologies (such as activated carbon for "chlorine") with innovative adsorbent resins for removing heavy metals, anions of higher oxidation state acids or lower oxidation state acids, micropollutants and bacteria is needed.

[0010] At a given contaminant distribution and a desired consumption rate, the productivity depends essentially on the residence time required in the adsorbent resin bed. For example, small particles are preferred here because the diffusion paths for the contaminants are short, however, on the other hand this increases the back pressure in an undesirable manner. Larger particles may require a larger bed, because a small bed may be difficult to stably fill with large particles; on the other hand, they are likely to require a longer residence time due to the longer diffusion paths.

[0011] Regarding the competing technologies available in the market, reverse osmosis (RO) is the most widely used technology. According to a 2017 market study by GrandView Research (Market Research Reports & Consulting), it has a market share of about 44% in the field of drinking water treatment. Global sales in 2016 totaled about 210 million units.

[0012] A serious disadvantage of RO modules is that they have a very low yield. Only about 10-20% of the incoming water is actually purified and available to the customer. Another disadvantage is the need for electricity for the required pumps and water quality: RO systems supply pure water without the necessary salts, which then have to be added with salts (such as calcium and magnesium) again.

[0013] The disadvantage of very high energy consumption is common to distillation processes. In addition, here, as in the case of reverse osmosis, health-promoting elements are also removed, resulting in distilled water that is not suitable for long-term consumption and important components such as magnesium salts must be added again in a subsequent step.

[0014] Water purifiers that combine several filtration technologies in a single unit / cartridge require complex plumbing with corresponding valves or connectors which are however prone to the possibility of malfunctioning and starting to leak etc. Furthermore, the connections are precisely the points where bacteria etc. have a particularly good chance to grow due to the flow conditions.

[0015] Known filter media used on the market are, for example, activated carbon, which is used as a granular packed bed in a filter cartridge with linear throughflow or as a pressed hollow cylinder with radial throughflow. Summary of the invention

[0016] According to a first aspect of the present disclosure, there is provided a method for preparing particles incorporating a perfluorinated surfactant, wherein the method comprises the following steps:

[0017] (a) providing an aqueous suspension comprising a polyamine, a crosslinking agent and a porous organic or inorganic support material in the form of particles in a mixer at a temperature of 10° C. or less to coat the support material with the polyamine;

[0018] (b) crosslinking the polyamine in the pores of the support material and simultaneously removing water.

[0019] According to a second aspect of the present disclosure, there is provided a porous particle prepared by the method according to the first aspect of the present disclosure.

[0020] According to a third aspect of the present disclosure, there is provided use of the porous particles according to the second aspect of the present disclosure or the porous particles prepared according to the method of the first aspect of the present disclosure for binding or removing perfluorinated surfactants in drinking water. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Glycidyl-2,2,3,3,4,4,5,5-octafluoropentyl ether,

[0022] Figure 2 : One of the two structural isomers of absorbents for perfluorinated surfactants (R = polymer),

[0023] Figure 3 : Chromatographic breakthrough curve on PV 150772 (instrAction resin batch: batch number ND 150201); breakthrough was not achieved until about 900 min later or 220 mg PFOA / mL resin. DETAILED DESCRIPTION

[0024] Potentially toxic micropollutants are increasingly becoming a focus of public and expert attention.

[0025] This applies in particular to perfluorinated surfactants (eg perfluorooctanoic acid), which are not or barely biodegradable and therefore have a very high persistence (“Sachstandsbericht ADONA und perfluorierte Substanzen” [“Evaluation Report ADONA and Perfluorinated Substances”], source: Bavarian State Office for Health and Food Safety).

[0026] There are a number of very inefficient and expensive methods for removing perfluorinated surfactants from drinking water, such as, for example, filtration through activated carbon, which has only a very low capacity for this type of contaminant, or membrane processes, which, although they provide clean drinking water, simultaneously produce large amounts of wastewater containing perfluorinated surfactants in concentrated form. Furthermore, they must be disposed of at a certain cost (usually incinerated), or they re-enter the wastewater. To the best of our knowledge, there are currently no selective adsorbents with a high capacity for perfluorinated surfactants.

[0027] The object arising from this was to modify and further develop the known resins in such a way that, in addition to heavy metals and bacteria, they also remove perfluorinated surfactants from drinking water.

[0028] As shown in the technical solution of this article, this problem has been solved.

[0029] The problem is solved by a method for preparing particles incorporating a perfluorinated surfactant, the method comprising the following steps:

[0030] (a) providing an aqueous suspension containing a polyamine, a crosslinking agent and a particulate porous organic or inorganic support material in a mixer at a temperature of less than or equal to 10° C. to coat the support material with the polyamine;

[0031] (b) Crosslinking of the polyamine in the pores of the support material while removing water.

[0032] According to the present invention, it is preferred that steps (a) and (b) are repeated at least once.

[0033] According to a preferred embodiment of the process, the crosslinking is carried out in a stirred reactor.

[0034] It has been found that the polyamines are advantageously used in a non-desalting state.

[0035] According to another embodiment of the present invention, the organic carrier material is selected from polystyrene, polymethacrylate or polyacrylate.

[0036] The organic support material is particularly preferably polystyrene.

[0037] According to a further embodiment, the organic support polymer is a strong or weak anion exchanger coated with a polymer only on its outer surface. Strong anion exchangers are those organic polymers having sulfonic acid groups. Weak anion exchangers are polymers having carboxylic acid groups.

[0038] The support material may also be an inorganic polymer selected from silica gel or hydroxyapatite.

[0039] Furthermore, it is preferred if the polyamine is polyvinylamine.

[0040] According to another embodiment of the method of the present invention, it is preferred that the polyamine in the pores and / or on the surface of the coated particles is glycidyl-2,2,3,3,4,4,5,5-octafluoropentyl ether

[0041]

[0042] coated, which are modified in the side chains.

[0043] Another object of the present invention is the porous particles prepared by the above process.

[0044] Preferably, the porous particles contain a substituent

[0045]

[0046] Wherein R is the polymer polyvinylamine.

[0047] Therefore, another object of the present invention is also to use the porous particles as described above or prepared by the method described above for binding or removing perfluorinated surfactants from drinking water.

[0048] Resins that can remove heavy metals (WO2015EP01754, WO2016EP78787) and bacteria (DE102017007273.6) from drinking water are known. Here, amino polymers are fixed on corresponding supports and reacted with bifunctional crosslinkers to form a stable three-dimensional network. Therefore, the resin is suitable both as a filter for heavy metals in drinking water purification plants and as a filter for "polizé filter" for removing heavy metals at the end of the purification cascade of an orthogonal method.

[0049] In the first step of resin preparation, the desired coating polymer, polyvinylformamide, is prepared and hydrolyzed by sodium hydroxide solution in a polymer-analogous reaction to form polyvinylamine (PVAm). The reagents are then removed and the product isolated by time-consuming and cost-intensive cross-flow filtration. This desalinated polymer solution is now used in the second step to coat the support material.

[0050] The aim arising from environmental issues (reduction of energy consumption and wastewater volumes) and market demands for drinking water purification systems is to simplify the preparation processes and to make them cheaper and more resource-efficient.

[0051] So far, only the so-called The particles can successfully remove bacteria from solutions treated on the basis of silica gel or without a carrier (DE102017007273.6). The preparation and detection of activity are disclosed in DE102017007273.6. It describes the coating of silica gel particles (as a template) with undesalted polymers, the subsequent dissolution of inorganic carriers and their antibacterial activity.

[0052] For particles based on organic supports (e.g. polystyrene), there has been no known corresponding activity so far. Now surprisingly, this activity could be established on polystyrene-based resins prepared according to the new method. This observation is surprising, since polystyrene generally tends to form a pronounced biofilm and certainly cannot remove bacteria. Apparently, the new coating ensures that bacteria do not grow on the polystyrene surface, but rather force the bacteria to leave the substrate (here drinking water).

[0053] A series of objectives arising from the above reasons are to develop and further develop the known resins with the following goals:

[0054] Simplify the current preparation methods used to prepare instrAction MetCap and BacCap resins, reduce waste streams, expand the product range by combining the performance of ion exchangers with adsorbent resins prepared for binding perfluorinated surfactants, which represent a growing problem in drinking water treatment. In addition, it will be very advantageous to expand the product range to organic supports such as polystyrene, as they are inexpensively available in different specifications regarding particle size and pore size. Polystyrene has good application mechanical properties and is well established on the market.

[0055] Simplification of the preparation process using polystyrene-based resins is achieved by omitting the desalting step of the polymer hydrolysate and by further process changes particularly concerning the addition of the carrier polymer and drying to form the polymer solution.

[0056] Surprisingly, it is possible to prepare the polymer solution without prior desalting by immobilization on porous polystyrene particles. and This is all the more surprising since in earlier studies it was found that the rate of deposition or immobilization of the polymer on the porous support depends significantly on the salt content of the polymer hydrolysate.

[0057] By adjusting the coating method (e.g., multiple coatings, Drying in a ploughshare mixer, introducing a new washing strategy) can save the complex and expensive process step of desalting the polymer hydrolysate without having to accept product efficiency limitations.

[0058] In summary, it can be said that changing the preparation process, in particular dispensing with the desalination by membrane filtration and extending to organic support materials, brings decisive advantages.

[0059] The polymer content is now determined by batch calculation during the polymerization. The authors were surprised that the coating and pre-crosslinking by ethylene glycol diglycidyl ether in a vacuum shovel dryer functioned exactly the same as a salt-free PVAm polymer solution. The salts contained were then partially dissolved during the preparation of the suspension for post-crosslinking. After the silica gel of the support was brought into solution with the aid of sodium hydroxide solution, all salts (silicates, formates, chlorides, etc.) were rinsed out of the crosslinked pure organic template material. The resulting T or The T material has the same properties as the adsorbent resin according to the PVA polymer preparation method using desalination. This is the first improvement of this method, which comes as a big surprise, since it was generally assumed until now (which is also supported by data in the literature) that the volume requirements of the high concentration of salt in the polymer solution would prevent the particles from being effectively and completely filled with polymer, simply due to their size.

[0060] The second approach involves coating commercially available strong or weak ion exchangers with an antimicrobial PVA polymer shell.

[0061] Commercially available ion exchangers, in particular the cation exchangers used here, usually have acidic groups covalently bonded to a polymer support (e.g. polystyrene, acrylates, etc.). The acidic groups are carboxylic acids or carboxylates in the case of weak ion exchangers or sulfonic acids or sulfonates in the case of strong ion exchangers. Both types are used to soften drinking water.

[0062] In order to provide these ion exchangers with antimicrobial properties without significantly reducing their softening capacity, only an external coating of the particles is sought without modifying the acid groups in the particle pores, where most of the load-bearing capacity is located.

[0063] This object is achieved by using corresponding polymers, which cannot penetrate into the pores of the ion exchanger particles due to their size and their hydrodynamic radius. In the case of commercially available ion exchangers, the pore diameters are in the range of from 20 nm to 100 nm. For polymers with a size of 10,000-20,000 g / mol, these pores are impermeable.

[0064] In this method, in a preferred embodiment, only 2-25% of the outer portion of the particle is coated, measured at the particle radius. More preferably, only 2-10% of the outer portion of the particle is coated, measured at the particle radius. Most preferably, only 2-5% of the outer portion of the particle is coated, measured at the radius.

[0065] After hydrolysis of the amide groups of the polyvinylamine with sodium hydroxide solution and subsequent neutralization with hydrochloric acid, the polymer contains about 15-25% by weight of salts in the form of sodium formate and sodium chloride. In the case of unsalted polymer, the polymer content of the aqueous solution corresponds to 9-13% by weight.

[0066] In the methods (or processes) to date, salts are removed in a complicated manner by reverse osmosis and polymers with a salt content of less than 2.5% by weight are used. The new method allows this complicated and expensive desalination step to be omitted. Therefore, for the new method, it is preferred to use partially desalted polymers with a salt content of 2.5-15% by weight. It is more preferred to use partially desalted polymers with a salt content of 10-15% by weight. It is most preferred to use non-desalted polymers with a salt content of 15-25% by weight.

[0067] Example 1

[0068] 1712 g of wet carrier material, Lewatit S1567 ion exchanger, was directly transferred to the VT5 plowshare mixer. The ion exchanger was then dried at 80°C for 60 minutes. The moisture loss was determined by weighing the dried ion exchanger. 380 g of water was removed. The product temperature in the dryer was adjusted to 10°C. The mixer was operated at 180 rpm. Once the product temperature in the mixing drum reached 10°C, 225 g of ion exchanger, undesalted polyvinylamine solution batch: PC 18007 (polymer content 10%) cooled to 10°C, and 1 g of ethylene glycol diglycidyl ether (EGDGE) [2224-15-9] were weighed into a container, and deionized water was added until a total volume of 350 ml was reached. The mixture was placed in a mixer for 10 minutes and mixed at 10°C for 1 hour. The polymer adsorbate was then crosslinked at 80°C and 50 mbar under reduced pressure for 2 hours. The polymer-coated ion exchanger was then cooled to room temperature.

[0069] The particles were then transferred to a suitable suction filter and washed with the following solvents (BV = bed volume): 3 BV 0.1 M NaOH, 3 BV deionized water, 3 BV 0.2 M HCl, 3 BV water, 6 BV 0.1 M NaOH, 6 BV deionized water. The product BacCap was obtained as water-wet particles.

[0070] Example 2

[0071] 3 L of Lewatit S 8227 from Lanxess were washed with 15 L of deionized water on a glass frit with a porosity of 3. Then 2270 g of wet ion exchanger were weighed and placed in in a VT 5 vacuum shovel dryer. The ion exchanger was dried for 2 h at a jacket temperature of 80°C and a pressure of 30 mbar and a rotation speed of 57 rpm. After drying, 915 g of the dried ion exchanger were poured back into the VT 5 vacuum shovel dryer. The jacket temperature was adjusted to 4°C and, when the product temperature was below 20°C, 600 ml of deionized water were conveyed within 15 minutes by a peristaltic pump to the mixer operated at a rotation speed of 180 rpm. For coating, a batch of 227 g of polyvinylamine solution (polymer content 10%): PC 18007 and 227 g of deionized water were weighed into a container. As a crosslinker, 9.20 g of ethylene glycol diglycidyl ether (EGDGE) [2224-15-9] were weighed into another container. The crosslinker was added to the polymer solution and mixed thoroughly. The mixture was then conveyed to the Mixer. Adjust the mixer rotation speed to 240 rpm and keep the jacket temperature at 4°C. After addition, continue mixing at 240 rpm for 15 min. Then adjust the jacket temperature on the dryer to 80°C and reduce the rotation speed control to 120 rpm.

[0072] The particles were then cooled to room temperature again before being transferred to a suitable suction filter and washed with the following solvents: 3 BV 0.1 M NaOH, 3 BV deionized water, 3 BV 0.1 M HCl, 6 BV water. The BacCap product was obtained as water-wet particles.

[0073] Example 3

[0074] 500 g of carrier material, namely sulfonated polystyrene PRC 15035 (average pore size) with a water absorption capacity of 1.35 mL / g, was added. Average particle size 500μm) Direct inhalation VT5 plowshare mixer. The product temperature in the dryer was adjusted to 10°C. The mixer was operated at 180 rpm. Once the product temperature in the mixing drum reached 10°C, 225 g of a batch of undesalted polyvinylamine solution: PC16012 (polymer content 12%) cooled to 10°C, 20 g of ethylene glycol diglycidyl ether (EGDGE) CAS No. [2224-15-9] and 430 g of deionized water were weighed into a container. The mixture was placed in the mixer for 10 minutes and mixed at 10°C for 1 hour. The polymer adsorbate was then crosslinked at 65°C. The product was then cooled to room temperature. The particles were then transferred to a suitable suction filter and washed with the following solvents: 3BV 1M NaOH, 3BV deionized water, 3BV 2M HCl, 3BV water, 6BV 1M NaOH, 6BV deionized water. 1297 g of product was obtained as water-wet particles. Anion capacity (AIC): 471 μmol / g.

[0075] Example 4

[0076] Instructions for the preparation of cross-linked polymer porous particles with a particle size of 100 μm (Batch: BV 18007): First, prepare the polymer adsorbent: 750 g of carrier material, silica gel (AGC Si-Tech Co. MS gel D-200-100 batch: 164M00711) is directly transferred to the VT5 plowshare mixer. The product temperature was adjusted to 10°C. The mixer was operated at 180 rpm. As soon as the product temperature in the mixing drum reached 10°C, 1125 g of a batch of undesalted polyvinylamine solution: PC 18007 (polymer content 10%), cooled to 10°C, were weighed into a container and 23.2 g of ethylene glycol diglycidyl ether (EGDGE) CAS No. [2224-15-9] were added. The mixture was placed in the mixer for 10 minutes and mixed at 10°C for 1 hour. The polymer adsorbate was then dried at 80°C and 50 mbar (about 2 hours). The coated silica gel was then cooled to 10°C. For the second coating, 750 g of polymer solution PC 18007 (polymer content 10%) cooled to 10°C were weighed into a container and 15 g of ethylene glycol diglycidyl ether (EGDGE) CAS No. [2224-15-9] were added. The polymer solution was poured into the mixing drum within 5 minutes. The polymer adsorbate was mixed at 10°C for 30 minutes. The temperature in the mixer was raised again to 65°C for 1 h. 3 L of deionized water were added to the polymer adsorbate. This suspension was used for crosslinking. The coated silica gel suspended in water was transferred to a 10-l glass reactor with automatic temperature control. The suspension was stirred and heated to 80°C. Then, 317 g of epichlorohydrin CAS No. [106-89-8] were added within 20 minutes, so that the temperature in the reactor did not exceed 85°C. Then, 211 g of 1,2-diaminoethane [107-15-3] was added dropwise within 20 minutes. Then, 317 g of epichlorohydrin CAS No. [106-89-8] was added a second time within 20 minutes, and then 211 g of 1,2-diaminoethane CAS No. [107-15-3] was added again. Finally, 317 g of epichlorohydrin CAS No. [106-89-8] was finally added and the reaction was stirred at 85°C for 1 hour. The reaction mixture was then cooled to 25°C, 1500 ml of 50% NaOH was added, and the reaction mixture was stirred for 12 hours. The template particles were then transferred to a suitable suction filter and washed with the following solvents: 3BV 1M NaOH, 3BV deionized water, 3BV 2M HCl, 3BV water, 6BV 1M NaOH and 6BV deionized water. The product was obtained in the form of a wet cake.

[0077] Example 5

[0078] The adsorbent resin prepared according to Example 1, Example 3 or Example 4 is suspended in a solvent such as DMF. Then, 110 mol% of glycidyl-2,2,3,3,4,4,5,5-octafluoropentyl-ether (based on the amino groups of the starting resin, Figure 2 ) is added to the stirred resin suspension, and the suspension is stirred at 70°C for 12 hours. The suspension is then rinsed with the following solvents using a syringe: 3BV DMF, 3BV n-heptane, 3BV 1M HCl in DMF, 3BV 1M NaOH in DMF, and 3BV DMF. A 50% suspension in DMF is then prepared again. In the second reaction step, 110 mol% glycidyl-2,2,3,3,4,4,5,5-octafluoropentyl ether is again added to the suspension. The reaction mixture is then stirred at 70°C for 12h. The adsorbent resin is then rinsed with the following solvents: 3BV DMF, 3BV n-heptane, 3BV 1M HCl in DMF, 3BV 1M NaOH in DMF, and 3BV MeOH. The adsorbent resin can then be vacuum dried to constant weight. The structure of the adsorbent resin is in Figure 1Shown in.

[0079] Example 6

[0080] As prepared in Example 5, the adsorbent resin and activated carbon ( 45 μm) and commercially available 15C-18 chromatography gel (Kromasil, C18, 10 μm) were each poured into an HPLC column with dimensions of 33.5×4 mm, the column was sealed, and they were then analyzed frontally. For this purpose, a 100 ppm aqueous solution of perfluorooctanoic acid was prepared and pumped through the column until the capacity was exhausted. The breakthrough was measured by UV spectroscopy at 205 nm.

[0081] The following table (Table 1) gives the PFOA adsorbent capacities measured on three adsorbents:

[0082] Table 1. PFOA capacity of the perfluorinated surfactant selective instrAction gel ND 150201 compared to commercially available adsorbents

[0083]

[0084] As shown in Table 1, on the instrAction phase (Batch ND 150201), the PFOA adsorbent capacity was approximately 3-4 times greater than that of activated carbon. The commercially available RP18 gel did not show adsorption of PFOA.

[0085] The breakthrough curve of positive analysis is Figure 3 Shown in.

Claims

1. A method for preparing particles conjugated with perfluorinated surfactants, wherein the method comprises the following steps: (a) Providing an aqueous suspension comprising a polyamine, a crosslinking agent, and a porous organic or inorganic carrier material in the form of particles in a mixer at a temperature less than or equal to 10 °C to coat the carrier material with the polyamine; (b) Crosslinking the polyamine in the pores of the carrier material and simultaneously removing water; Among them, the polyamine in the pores and / or on the surface of the coated particles uses glycidyl-2,2,3,3,4,4,5,5-octafluoropentyl ether on the side chain for modification.

2. The method according to claim 1, wherein steps a) and b) are repeated at least once.

3. The method according to claim 1 or 2, wherein the crosslinking is carried out in a stirred reactor.

4. The method according to claim 1 or 2, wherein the polyamine is used in a non-desalted state.

5. The method according to claim 1 or 2, wherein the organic carrier material is polystyrene, polymethacrylate, or polyacrylate.

6. The method according to claim 1 or 2, wherein the carrier material is an inorganic polymer selected from silica gel and hydroxyapatite.

7. The method according to claim 1 or 2, wherein the polyamine is polyvinylamine.

8. Porous particles prepared by the method according to any one of claims 1-7.

9. The porous particles according to claim 8, wherein the porous particles comprise substituents wherein R is the polymer polyvinylamine.

10. Use of the porous particles according to claim 8 or 9 or the porous particles prepared by the method according to any one of claims 1 to 7 for binding or removing perfluorinated surfactants in drinking water.

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