Flow reactor comprising a sorption-photocatalytic filling for water purification and the use thereof

Abstract

The subject of the invention is a flow reactor comprising a sorption-photocatalytic filling for water purification and the use thereof for removing dissolved biologically active substances, in particular drugs and opiate substances, as well as heavy metal ions, from water. The reactor comprises a composite filling that consists of the agglomerates of primary natural halloysite particles combined in the form of mesoporous structures, modified with TiO2 nanoparticles and decorated with Cu nanoparticles. The reactor is also characterized in that it comprises a filling of composite halloysite particles selected from the stationary and fluidized one. The energy needed to conduct the photocatalytic process is provided by a source selected from among the LED sources distributed uniformly throughout the reactor space and from an external LED source through a fibre optic system. Preferably, the reactor further comprises a prefiltration system disposed in front of it and an end filter disposed behind it.

Description

[0001] Flow reactor comprising a sorption-photocatalytic filling for water purification and the use thereof

[0002] The object of the present invention is a flow reactor comprising a sorption-photocatalytic bed for water purification and the use thereof for removing dissolved biologically active substances, in particular drugs and opiate substances, as well as heavy metal ions, from water.

[0003] Water is the basic chemical compound which life on Earth is built upon. The ubiquity of this component demonstrates its importance and the need of maintaining the accessibility of water sources. This is particularly true for drinking water.

[0004] According to the World Water Development Report 2020, "Water and climate change", 2.2 billion people lack access to drinking water, and 4.2 billion lack access to sanitation. Over the past 100 years, global water consumption has increased sixfold, and this rising trend continues at about 1% per year as a result of a growing population, industrialization, and irrational consumption. In view of the above, there is an imperative need to rationalize the use of water and improve its quality. One way to improve this is to use high-efficiency methods of purifying water from natural intakes and water subject to recycling processes, which is a necessary step, especially in areas with limited resources.

[0005] As a result of using modern measurement methods, there is a natural identification of potential hazards arising from the presence of biologically active substances in water which pose a potential threat to the health and life of living organisms. For years, the problem went unnoticed, but as a result of the accumulation of certain components that are not subject to natural decomposition, an increase in the production and consumption thereof, the presence of active substances in surface waters constitutes a real problem that must be faced now. In view of the above, new regulations are being put forward, forcing the need to develop new methods for water purification. The modification of the European Drinking Water Directive, Drinking Water Directive DWD 98 / 83 / EC, addresses i) improving accessibility to drinking water, ii) raising drinking water standards, and iii) increasing transparency through access to information on requirements for consumer representatives. The requirements of the Directive entail the development of new solutions leading to the efficient removal of hazardous substances from water. These are already well-known biologically active substances such as metal ions, organic compounds used in or being products of technological processes, microorganisms, viruses, and other particles. Attention is now being drawn to the increasing concentration, in water sent through the water supply system, of pharmaceutical compounds such as contraceptives, oncological drugs, painkillers, opiates, and others, for which reaching a certain level of concentration may pose a significant threat to the population balance and health. Other dissolved components present in the water and hazardous to health are heavy metal ions such as mercury, cadmium, lead, and others.

[0006] The currently applicable water purity standards, specifying the scope of the required tests and setting the level of permissible contaminants, cover selected heavy metals, but do not include the obligation to monitor active pharmaceutical compounds (not required by the provisions set out in the "Regulation on the Quality of Water Intended for Human Consumption" Journal of Laws 2017, item 2294). In recent years, assays carried out within the scope covered by the standards and control tests that the standards do not cover have revealed the presence of compounds of pharmaceutical origin which can be removed by existing processes used in wastewater and water treatment technologies only with fairly limited effectiveness, as these processes and equipment are designed to remove other contaminants. However, the presence of these compounds creates noticeable technological problems, especially in biological processes, including difficulties in maintaining stable operating conditions for activated sludge.

[0007] Existing technologies, currently under development, providing effective elimination of such contaminants, primarily include the use of suitably prepared sorbents, such as modified activated carbon and zeolites, as well as membrane processes. In the case of the latter, organic components or heavy metal compounds remain in the retentate, i.e. a liquid with a high concentration of impurities which is then sent for disposal (recovery and reuse of removed components are not used due to high costs, and for pharmaceutical compounds, production quality requirements according to GMP guidelines preclude this possibility).

[0008] In view of the above, new comprehensive methods for removing substances harmful to human and animal health should be introduced into the system of purifying water intended for consumption. Heavy metal ions can be removed with relatively high efficiency by physical sorption or chemisorption processes. Removal of biologically active organic compounds should be combined with their deactivation by using chemical processes causing a change in the molecular structure of the compound that determines its activity. Photocatalysis is an effective and efficient process that can be used in such an operation.

[0009] Photocatalytic materials, commonly known as photocatalysts, belong to a group of functional materials capable of, among other things, decomposing harmful organic substances, producing hydrogen, or converting CO2 to high-value-added chemicals through their interactions with light [1], The photocatalytic effect is possible due to the reducing action of excited electrons and the oxidizing effect of holes created as a result of photoexcitation. Some of the most promising photocatalytic materials are metaldecorated oxide composite nanoparticles, e.g. titanium oxide (TiC>2) modified with a pair of metals palladium-gold (PdAu) [2,3], Despite the high photostability of TiC>2, its energy gap (band gap) is ~3.2 eV, and in the case of nanoparticles it may be even greater due to the so-called quantum confinement effect. Therefore, pure TiC>2 nanoparticles exhibit activity in the ultraviolet (UV) range which accounts for only ~5% of the solar spectrum, and this, in turn, translates into their low quantum efficiency (understood as % of energy from the full spectrum of solar radiation reaching the surface of the apparatus). Modification of TiC>2 nanoparticles by admixing selected metal ions or creating Ti02 / metal composite nanoparticles leads to a significant increase in the quantum yields of photocatalysis as a result of the following effects: 1) narrowing the TiC>2 band gap and shifting the absorption edge to the visible range, 2) delaying the recombination processes of electrons excited to the conduction band with holes formed in the valence band, 3) effective separation of electrons in the region of the metallic part and holes in the surface acceptor states of TiC>2 [4], The key to achieving the desired effect is a goodquality combination of a metallic nanoparticle and a semiconductor. A solution to this problem can be achieved by using a known method of sono-photochemical deposition [5] [6], This method exploits the synergy of ultrasonic waves and light, is inexpensive, repeatable, and leads to the formation of a high-quality metal-semiconductor composite, i.e. characterized by a permanent bond and uniform distribution of the introduced additives in the porous structure.

[0010] Bearing in mind the previously defined technical problem, the object of the invention is to develop a flow reactor for water purification at the final (most accurate) step of the process sequence - from the source of purified water to the point of water use by the consumer, characterized in that the basic element is a sorption-photocatalytic bed, wherein the sorption process is combined with a photocatalytic reaction leading to chemical decomposition of the sorbed organic, biologically active substances and neutralizing this activity, as well as the sorption of heavy metal ions. The object of the invention is a flow reactor comprising a sorption-photocatalytic bed, characterized in that the filling consists of a composite of aggregated, structurally modified halloysite particles with oxide particles, decorated with metal nanoparticles.

[0011] By “modified halloysite” is meant the primary particle of natural halloysite subjected to a physicochemical process (see Example 1), as a result of which the structure of the particle undergoes stratification, increasing the internal surface by raising the proportion of nanometric micropores, which results in a large value of the specific surface area, which in turn creates favorable conditions for the sorption of various water contaminants, e.g. heavy metal ions and organic compounds. This new product, which is the object of the patent, belongs to the group of so-called structurally high-entropy materials that create exceptional conditions for ion sorption. Consequently, the modified halloysite has mesopores in its structure that increase the near-surface concentration of bioactive substances (drugs) due to the capillary effect, thus leading to an increase in the photocatalytic reaction rate, and nanopores responsible for the sorption of ions. Preferably, the composite bed of the photocatalytic reactor consists of the agglomerates of primary modified halloysite particles with an average equivalent diameter size of 50- 100 micrometers, combined in the form of mesoporous structures with an average equivalent diameter of 1-10 mm and mesoporosity in the range of 50-70%.

[0012] Preferably, the modified halloysite particles with TiC>2 nanoparticles located on their outer surface are additionally decorated with Cu nanoparticles in sizes within the range of IQ- 150 nm for the TiO2 / Cu composite, wherein the mass proportion of Cu nanoparticles on the TiC>2 surface is 1-5%, and the mass fraction of Cu / TiC>2 aggregates on the halloysite particles is in the range of 0.5 to 2%.

[0013] Preferably, the reactor of the present invention comprises a bed of composite halloysite particles selected from the stationary and fluidized one.

[0014] Preferably, the reactor of the present invention comprises light-transparent walls.

[0015] Preferably, the reactor of the present invention comprises walls that are non-transparent to light, wherein the light energy required for photocatalysis comes from a source selected from among the LED sources distributed uniformly throughout the reactor space and from an external LED source through a fiber optic system.

[0016] More preferably, LED light has an electromagnetic radiation wavelength in the range of 360-550 nm. More preferably, LED light has a power of 10-40 W / 1 dm3of the suspended catalytic material.

[0017] More preferably, the luminous flux of LED light with respect to the power unit of the source is 100-150 Im / W.

[0018] Preferably, the reactor of the present invention in the form of a stationary composite filling comprises cylindrical containers filled with composite, with the walls transparent to LED light, uniformly distributed throughout the volume of the reactor.

[0019] Preferably, LED light is provided by means of optical fibers uniformly distributed within the intertubular space.

[0020] Preferably, LED light is provided by a uniform distribution of fiber optic sources throughout the reactor volume to the reactor of the present invention in the form of a fluidized composite filling.

[0021] Preferably, the cross-section of the reactor according to the invention is adapted to the set flow rate of purified water, so that the linear flow rate is 0.02-0.6 m / s.

[0022] Preferably, the reactor of the present invention further comprises a prefiltration system disposed of in front of it that is a non-woven tubular filter with an average porosity of 80%-90% and an average fiber diameter of 1-5 micrometers, wherein composite nanoparticles of transition metal oxides decorated with metal nanoparticles are located on the surfaces of the non-woven filter elements.

[0023] Preferably, the reactor of the present invention further comprises an end filter disposed behind it that is a non-woven tubular filter having a porosity of 80%-90% and an average fiber diameter of 1-5 micrometers.

[0024] Another object of the present invention is the use of the flow reactor comprising a sorption-photocatalytic bed according to the invention for removing dissolved biologically active substances, in particular drugs and opiate substances, as well as heavy metal ions, from water.

[0025] The advantage of the present invention is that the reactor according to the invention comprises a sorption-photocatalytic filling that is a composite of a sorbent and a photocatalytically active material. When selecting the sorbent, apart from its effectiveness against the selected contaminant, its availability, and price are important, taking into account the scale of the process and the possibility of its easy disposal after the process, due to the low leachability of the adsorbed components. An important property of the sorbent is its structure allowing it to locate photocatalytic material particles on the outer surface of the sorbent. Materials that meet these requirements are, among others, various types of aluminosilicates. According to the analyses of structural and sorption properties, as well as economic properties, halloysite is used in the present invention because of its tubular multilayer structure, resulting in a developed specific surface area. Its structural properties result in the experimentally confirmed sorption capacity of cations and anions as well as large-molecular organic compounds. Halloysite is a natural mineral from the kaolin group. Its chemical molecular formula is Al2Si2Os(OH)4-2H2O. The halloysite structure consists of aluminosilicate layers in a 1 :1 ratio and each layer is composed of octahedral aluminum sublayers combined with tetrahedral silicon layers.

[0026] In the case of sorbents, the cost of a suitably prepared sorbent and the sorption capacity are the parameters that determine cost-effectiveness. From a practical point of view, mechanical strength is also an important parameter that can affect the crushing of particles, blocking of the bed with fine dust particles, and significant re-emission of the smallest elements from the bed, which is a common problem with activated carbon beds. Halloysite composites lack the aforementioned disadvantages, i.e. they have good mechanical strength, which is important when high compressive forces are applied to the bed during the flow through the stationary layer, and can be used, for example, as a filler for building materials or polymers. The contaminants are deposited in the sorbent structure in a permanent way - they are strongly bound to the base material in active centers and basically are not leachable under ambient conditions.

[0027] To increase the efficiency of the process, the sorption-reaction element is protected by a prefiltration element that purifies the water. The purpose of prefiltration is to remove the structured forms of matter (solid particles, microorganisms, and viruses) in order to prevent these components blocking the active sites on the surface of the sorbent as well as avoid the increase in resistance to flow through the bed (decrease in permeability) that accompanies deposition.

[0028] The third element of the purification system is the end filter, responsible for removing from the water leaving the sorption-reaction element any re-emission components from the reactor and ensuring the required water quality that meets the requirements of the level of total suspended solids (TSS) and turbidity.

[0029] For a better understanding of the present invention, drawings are provided, wherein: Fig. 1 shows a diagram of the reactor (in cross-section) with a photoactive fluidized bed;

[0030] Fig. 2 shows a diagram of a halloysite particle aggregate;

[0031] Fig. 3 shows a diagram of a halloysite aggregate (composite) particle decorated with TiC>2 and Cu particles;

[0032] Fig. 4 shows a diagram of the reactor (in cross-section) with a photoactive stationary bed;

[0033] Fig. 5 shows a diagram of inserts limiting the bed volume (cross-section).

[0034] Examples

[0035] Example 1

[0036] In the example of halloysite sorption capacity testing, the sorption of metal ions and selected dyes were measured. The tests were carried out in a suspension wherein the sorbent particles present at concentrations ranging from 0.5 to 5 g / L were maintained in a suspended state by stirring. Concentrations of metal ions in the aqueous stock solution were equal to 10-fold of the permissible concentration levels in treated drinking water and were respectively: for Cd - 2 mg / L, for Cu - 1 mg / L, for Cr - 5 mg / L, for Pb - 1 mg / L, for Zn - 10 mg / L. Ion concentrations were determined after a period of 1 to 4 hours (ensuring that equilibrium was reached), which allowed us to determine the sorption capacity of the material against a given contaminant. Laboratory-scale studies indicate the ability to adsorb selected heavy metals, important from the point of view of their occurrence in surface waters and the need to reduce their concentration in drinking water. Already in the case of raw unpurified material, by examining the sorption of heavy metals (including Cd, Cu, Cr, Pb, Zn), results were obtained confirming the ability of halloysite to adsorb the aforementioned metal ions. The raw material used in the first laboratory tests was not subjected to purification, activation, or any other processes affecting its structure. In this state, the highest sorption capacity was obtained with respect to lead ions and it was at a level exceeding the value of 1 mg / g for unpurified raw material. However, studies carried out for the processed halloysite showed a significant influence of secondary treatments modifying the halloysite structure on its sorption capacity in relation to metal ions. Studies conducted for purified halloysite and subjected to external physical interactions aimed at forcing secondary structural changes on the submicron scale showed large differences in sorption capacity. Among other things, the removal of primary contaminants and activation by acting on the sorbent with a sulfuric acid solution at elevated temperatures resulted in a slight decrease in sorption capacity. This gives reason to claim that suitable metallic additives (possibly removed from the structure in the activation step), introduced into the structure in a controlled manner, may contribute to a significant improvement in the sorption capacity of the material. In addition, acting on the structure through thermal freeze-thaw processes of water that the sorbent particles were saturated with resulted in a noticeable improvement in sorption capacity. This was probably the result of layer separation and greater accessibility of active sites in the sorbent volume (improved diffusion transport efficiency). With such a simple procedure, sorption capacity increased significantly. The presented simple modification methods carried out at the initial step of determining the effectiveness of the sorbent and the ease of its modification (adaptation to a given type of contaminant) indicate its great potential for functionalization, aimed at specific applications. Scientific literature of recent years is undeniable proof of this, with the material being of great interest to researchers. Modification methods include various techniques, including chemical methods (e.g. oxidation of TiH2 using H2O2 or TiCk hydrolysis by NH4OH and glycerol), hydrothermal sol-gel synthesis with the application of functional metallic additives incorporated into the sorbent structure. The starting point, however, is suitable preparation - purification, and activation - of the base material. A variety of chemical methods using strong acids, bases, perhydrol, and others serve this purpose. Best results were obtained for the modification using 25% vol. sulfuric acid (aqueous solution) at a temperature of 80°C and for a processing time of 2 hours. The process was carried out in a stirred suspension, from which particles were separated after the process, and then washed repeatedly with deionized water until a neutral pH was reached. Thus, prepared material (modified halloysite) was characterized by a more than 5-fold increase in the specific surface area in relation to the starting raw material (from the value of about 30 to over 160 g / m2) and an increase in the proportion of pores in the range of 0.5-2.0 nm (micropores, probably related to the interlayer space of nanotubes) as well as in the range of 2-50 nm (mesopores, between grains and inside nanotubes).

[0037] Example 2

[0038] For the sorption of dyes, we have conducted the sorption of positively and negatively charged dye molecules, i.e. methylene blue (MB) and methyl orange (MO). Measurements were made for each dye separately and from the mixture thereof. The sorption capacity of individual dyes was 10 mg / g for MB and 4 mg / g for MO, and as for the sorption from the mixture of both dyes, it was 12 mg / g for MB and 2 mg / g for MO. The above results indicate good sorption capacity of halloysite for metal ions and unique sorption properties for various organic compounds. The layered structure of halloysite makes it possible to effectively modify it in order to increase the sorption capacity of the material.

[0039] Example 3

[0040] In the proposed solution the sorption process is associated with the decomposition of the molecular structure of the adsorbed biologically active compounds contained in water through a photocatalytic reaction process on catalyst particles, embedded in the sorbent structure. Such a combination creates conditions for the highly effective degradation of biologically active substances whose concentration in the sorbent area is much higher than their concentration in the stream of purified water.

[0041] There are a number of possible molecular structures that ensure an efficient photocatalytic decomposition process. When analyzing potential structures for our solution, due to the predictable process scale, we were guided by material availability and price. As a result of the analysis, in our solution, we propose using a TiO2 / Cu system in the form of composite nanoparticles. The developed photocatalyst consists of TiC>2 nanoparticles with medium sizes in the range of 10-150 nm, surface-coated with Cu, wherein the mass proportion of Cu is comprised in the range of 1-5%. The composite photocatalyst nanoparticles, on the other hand, are uniformly dispersed on the outer surface of halloysite tubes by sonodiffusion or synthesized directly in its structure. The basic element of the sorption-photocatalytic reactor according to the invention is a composite containing halloysite particles of average diameter size preferably in the range of 0.1-1 mm with nanoparticles of the TiO2 / Cu system with sizes in the range of IQ- 150 nm distributed on their surface. This structure of the composite results in a capillary effect associated with the tubular structure of halloysite particles and high curvature at the interface between the photocatalyst nanoparticles and the catalyst surface, producing a driving force that increases the local concentrations of the removed compounds contained in water at the site where the photocatalytic reaction takes place. All this effect significantly increases the efficiency of the process compared to the conditions existing in the entire volume of purified water. Such primary composites are assembled into a mesoporous structure of a specific size ensuring effective mass transport in the overall photocatalytic process. The TiO2 / Cu system exhibits high activity in the case of photocatalytic degradation of various types of compounds of pharmaceutical origin [7], An example is the photocatalytic degradation of ibuprofen, where it is possible to completely mineralize it by using TiC>2-based nanoparticles, i.e. convert it to CO2 + H2O [8], Achieving high efficiency in the degradation of ibuprofen as well as other compounds of pharmaceutical origin is possible due to the parallel action of the following mechanisms: 1) direct chemisorption of the compound on the surface of the TiC>2 / Cu photocatalyst and its subsequent oxidation by using holes generated in the TiC>2 valence band as a result of photoexcitation; 2) generation of highly oxidizing radicals (mainly hydroxyl -OH) on the surface of the photocatalyst that attack electron-rich regions of the pharmaceutical compound, such as C=C aromatic rings, leading to their decomposition.

[0042] Theoretical studies carried out by the inventors using atomic-scale modeling by the density functional theory (DFT) method show a strong anisotropy of heavy metal adsorption on the halloysite surface. In the case of lead, the difference in adsorption energy on the surface parallel to the aluminosilicate layers relative to the cross-sectional surface of these layers is up to 1 eV. In addition, the results show that the migration of a lead atom between the aluminum silicate layers is characterized by a low barrier of ~0.2 eV showing its potentially high sorption capacity. Due to the spatial separation of the active sites of the mesoporous halloysite structure modified with photocatalytic TiO2 / Cu nanoparticles (adsorption and decomposition of biologically active substances on TiC>2 / Cu nanoparticles decorating the outer surface of halloysite tubes vs adsorption of heavy metal ions on the surface perpendicular to the aluminum silicate layers and their migration into the halloysite structure), the proposed solution is a novelty and has great application potential in modern active water filtration systems.

[0043] The global water purification process in the photocatalytic unit of the purification system is carried out by the flow of purified water in the reactor, where the particles of the reactive composite can be suspended (in the form of a fluidized bed or a tank with hydrodynamic or mechanical mixing) or a stationary bed depending on the specific solutions related to the scale of the process.

[0044] Example 4

[0045] When considering photoactive sorbent particles with sizes in the range of 250-1000 pm, it is possible to maintain them in a suspended state or place them in a stationary bed. Maintaining particles in the suspended state may be realized e.g. in a reactor with a mechanical stirrer, wherein particle concentration in the suspension may be up to a maximum of about 10% by weight - above the specified value the amount of energy supplied for mixing increases significantly, as well as the risk of particles interacting with each other and the abrasion thereof that hinders separation in the further step. Under such conditions, the permeability of the suspension for radiation is much better than that of a stationary bed, but, most importantly, the particles move relative to the walls of the mixer through which the light is delivered, and the probability of "excitation" on the surface of each particle is higher. The same is true of a fluidized bed reactor, wherein the particles can move relative to each other and to the walls of the column. An average flow rate through the column of about 0.02-0.6 m / s is required to keep the material of the above grain size fluidized. At the same time, it is worth emphasizing that stable operation of the bed is possible only if the particle distribution is as narrow as possible (particles that are too small would be washed out and block the upper baffle limiting the bed in the column). These conditions clearly determine the residence time, relevant from the point of view of individual steps in the photocatalytic-sorption process. Changing the hydrodynamics and thus influencing its value can be done within a very narrow range, which is a direct result of controlling the operation of the fluidized column. By combining fluidized sections in series, it is possible to influence the contact time of purified water with the bed and the overall efficiency of the process.

[0046] The process conditions necessary for the efficient running of the process impose requirements both on the adequate exposure to electromagnetic radiation with wavelengths in the appropriate range, and on the average residence time in the reactionsorption volume of the apparatus. The process is therefore defined by time scales related to the rate of decomposition and sorption, wherein the latter may be affected by internal diffusion in the halloysite mesopores. The system is subjected to light radiation in a continuous manner, wherein due to the high density of the solid medium (composite particles), suitable dispersion of its sources throughout the reaction volume is required. The distribution of light sources introduced to the surface of the bed particles, their energy and characteristics, as well as the composition of additives significantly affect the kinetics of the decomposition reaction, and the required residence time in the reactionsorption zone of the reactor is directly related to that kinetics. In the case of small reaction-sorption units with diameters below 10 mm, it is possible to supply energy from the outside through a transparent housing with an appropriate permeability in the wavelength range of 360-550 nm. In larger equipment, it is possible to divide the volume into tube bundles embedded in common sieve bottoms and locate light sources in the extratubular space. A design with plate baffles is also possible, i.e. a bed of a photoactive sorbent is placed in the spaces separated by flat baffles made of light-permeable material in the external volumes and every other such space, while radiation is supplied through the outer walls and between the bed. For this type of design, a rectangular cross-section of the reactor tank is preferred. An alternative solution is to disperse light sources in a space filled with grainy photoactive material using optical fibers. In the case of a fluidized bed reactor, the distance between cylindrical light sources (optical fibers) is 5-15 mm, whereas for a stationary bed the distance required to ensure the supply of adequate energy for the efficient process operation should be in the range of 3-10 mm. The power supplied to the system in the form of light radiation with a wavelength range of 360-550 nm should be at least 10-40 W per 1 dm3of bulk material. The size of the apparatus is determined by its capacity, i.e. the size of purified media and the hydrodynamic conditions that ensure appropriate residence time and local flow rates at the required level, preferably in the range of 0.0001-0.005 m / s for a stationary bed. The latter is important from the point of view of achieving suitable (not excessive) flow resistance per unit layer thickness. In the case of a fluidized bed apparatus (i.e. with a moving bed), the operating range is significantly narrower and results from maintaining the active material in a suspended state. For the given granulometric range, the speed range is preferably in the range of 0.02-0.6 m / s. In this case, the flow direction must be from the bottom upwards, while in the case of a stationary bed design (a fixed material layer), the flow in the horizontal direction is possible.

[0047] The light source in the photocatalytic unit of the system, depending on the conditions of the immediate environment, may be sunlight entering the sorption-photocatalytic reactor through the reactor walls, or (for reactor tanks non-transparent to light) the light energy necessary for the process is supplied from LED sources mounted directly in the reactor or supplied from an external LED source by means of optical fibers distributed in the reaction space.

[0048] Example 5

[0049] The embodiment of the solution described below presents test results relating to the performance capabilities of the photocatalytic unit of the water purification reactor that is the object of the present invention.

[0050] Tests confirming the effectiveness of the method were carried out in the reactor shown schematically in Fig. 1.

[0051] In an embodiment, the reduction of ibuprofen concentration in water was measured using the fluidized bed reactor shown in Fig. 1. The main part of the reactor was a cylindrical tank made of quartz glass permeable to radiation in the wavelength range corresponding to the visible and UV light range. The internal diameter of the reactor was D = 45 mm, and the total height of the cylindrical part between the grates 5 and 6 was equal to H = 200 mm. The active part of the reactor was closed by steel mesh elements with a mesh size of 150 pm which kept the bed inside the reactor. The fluidized bed consisted of composite halloysite particles 7 whose surface was decorated with TiC>2 particles with a Cu particle coverage applied to their surface. Composite particles (halloysite with admixtures, Fig. 2) had a diameter in the range of 300-500 pm, wherein these particles were derived directly from the screened fossil halloysite. Individual halloysite particles (Fig. 3) were decorated with TiC>2 particles with an average equivalent diameter size in the range of 50-100 nm and Cu nanoparticles of 5-30 nm.

[0052] Preparation of the composite reaction particles (Fig. 2 and 3): a) From the fossil halloysite subjected to the calcination and grinding processes onsite, a fraction of 300-500 pm was isolated (by means of sieving), which resulted in a particle size fraction favorable for the process (low flow resistance, sufficiently high fluidization speed, ease of bed maintenance and reduced migration of particles from the photoreactor zone. Further processing (deposition of active particles on the halloysite surface) did not significantly affect the specified initial size range. b) TiC>2 particles with a diameter in the range of 50-100 nm were coated with Cu particles using the magnetron atomization method. Their sizes were in the range of 5- 30 nm. c) The target composite was obtained in the process of sonication. For this purpose, halloysite particles and TiC>2 particles with Cu particles previously deposited on their surface were placed in a 400 ml vessel with water, wherein the weight of the halloysite particles was 100 g and that of the TiO2 / Cu aggregates was 5 g. Thus, the prepared mixture was initially homogenized and then subjected to ultrasonic waves from a 22 kHz source with a power of 300 W. After a period of 15 minutes, the target composite was obtained (Fig. 3). d) Particles of coated halloysite were separated from the aqueous suspension on a 300 pm mesh sieve (in order to dispose of the particles of the undeposited additives).

[0053] The activities mentioned in a) to d) allowed to preparation of composite particles for the sorption-photocatalytic filling.

[0054] The reactor (Fig. 1) was filled with prepared composite particles weighing 90 g by placing them on a porous support baffle 5 (mesh) and closed from above with an identical support baffle 6 and a bottom with an outlet port - the static bed constituted about 30- 40% of the height of the cylindrical part between the baffles. Then the entire volume of the reactor and the external circulation loop system (pump, piping) was filled with deionized water, wherein 10 pg / ml of ibuprofen was dissolved, using valve 4 (valves 3 and 8 were closed). Subsequently, a circulation pump was activated, which ensured appropriate hydrodynamic conditions - achieving a suitable flow rate ensuring fluidization, but at the same time not causing excessive entrainment of the particles (which would be counteracted by baffle 6, but then the conditions for effective fluidization would not be met). In the experimental reactor, i.e. a column with a diameter of 45 mm and a height of 200 mm, in order to provide a computationally estimated average speed of about 0.03 m / s in the reaction zone, sufficient to maintain the bed in a fluidized state, the circulation pump operated at a capacity of about 0.2 m3 / h. In such a state, apart from improving mass transport coefficients, fluidization also promotes better permeability of visible radiation through the suspension. At the same time as starting the pump, the source of external illumination 9 was also switched on, which was provided by LED diode panels with a total power of 100 W, emitting light radiation in the wavelength range of 360-375 nm. The diodes powered from source 10 were arranged in cylindrical housing covering the entire height of the fluidized bed section where the composite bed was located. During the experiment, samples were taken through valve 8 to analyze the concentration of ibuprofen in water and determine its changes during the process.

[0055] Results of experimental tests

[0056] • initial concentration of ibuprofen: 10 pg / ml (10 mg / l),

[0057] • total concentration of ibuprofen and its degradation components in water after a processing time of 1 hour: 5.92 pg / ml.

[0058] The main sorption-photocatalytic unit of the water purification reactor is protected by a prefiltration unit purifying water introduced into the reactor and a post-process filtration unit protecting water directed from the reactor to the consumer against possible components derived from the re-emission of components from the reactor unit to water. The prefiltration unit is a depth filter, whose filling is constituted by a non-woven or granular structure. For lower concentrations of the structured forms of matter removed in the prefiltration unit, a non-woven pleated filter can be used.

[0059] Due to the possibility of microorganisms being present in the purified water, which after filtration may colonize the spatial structure of the filter causing its blockage, nanoparticles of transition metal oxides or composites of these oxides decorated with precious metals are introduced onto the fibers or grains of the filling. Such a solution inhibits the growth of filtered microorganisms or causes their death, extending many times the useful life of the prefilter and helping avoid the re-emission of retained objects into the reaction unit of the system. Nevertheless, halloysite-based photoactive particles have bacteriostatic properties confirmed in earlier studies for selected bacterial strains.

[0060] Example 6

[0061] Tests confirming the effectiveness of the stationary bed reactor were carried out in the reactor shown schematically in Fig. 4. As in Example 5 (concerning the fluidized bed), measurements were made to reduce the concentration of ibuprofen in water using a reactor filled with a stationary granular bed, as shown in Fig. 4 - the bed (granular material) had the same parameters as in Example 5. The main part of the reactor was a rectangular tank made of plastic (PVC), wherein the bed was stacked into a pocket with a rectangular cross-section, whose dimensions were determined by:

[0062] • side walls on three sides,

[0063] • steel mesh elements with a mesh size of 150 pm on two sides, on the inlet and outlet sides,

[0064] • on one side, a glass element made of quartz glass permeable to radiation in the wavelength range corresponding to the visible and UV light range.

[0065] The dimensions of the pocket in cross-section (rectangular dimensions) were 40 mm (X) and 200 mm (L), and the total depth of the chamber was 40 mm. On the side of the light source, the side wall consisted of a glass element, while before the bed was stacked, provision was made for installing an insert 12 inside the pocket, which allowed changing the thickness of the granular layer - the distance from the light source. The purpose of installing inserts 12 (of various shapes) was to change the amount and geometry of the stacked bed so that the bed volume was identical in all cases, and only the depth of the bed relative to the light source (and not the amount of sorption-photocatalytic material) changed in the range of 10, 20 and 40 mm.

[0066] The operation mode of the reactor and the initial conditions of the ibuprofen solution in water were identical to those in the experiment described in Example 5. The only difference was the flow rate value which was significantly lower compared to the fluidized bed reactor and amounted to about 7 dm3 / h, which corresponds to an apparent flow rate of about 5 mm / s.

[0067] Results of experimental tests Initial concentration of ibuprofen in water: 10 pg / ml (10 mg / l).

[0068] The total concentration of ibuprofen and its degradation components in water after a processing time of 1 hour:

[0069] • bed with a depth of 1 cm from the light source: 6.37 pg / ml,

[0070] • bed with a depth of 2 cm from the light source: 7.54 pg / ml,

[0071] • bed with a depth of 4 cm from the light source: 7.95 pg / ml.

[0072] References

[0073] [1] J.C. Colmenares, R. Luque, Heterogeneous photocatalytic nanomaterials: prospects and challenges in selective transformations of biomass-derived compounds, Chem. Soc. Rev. 43 (2014) 765-778.

[0074] [2] C. Han, X. Yang, G. Gao, J. Wang, H. Lu, J. Liu, M. Tong, X. Liang, Selective oxidation of methanol to methyl formate on catalysts of Au-Ag alloy nanoparticles supported on titania under UV irradiation, Green Chem. 16 (2014) 3603-3615. doi: 10.1039 / C4GC00367E.

[0075] [3] K. Czelej, K. Cwieka, J.C. Colmenares, K.J. Kurzydlowski, Y.-J. Xu, Toward a Comprehensive Understanding of Enhanced Photocatalytic Activity of the Bimetallic PdAu / TiO2 Catalyst for Selective Oxidation of Methanol to Methyl Formate, ACS Appl. Mater. Interfaces. 9 (2017) 31825-31833. doi:10.1021 / acsami.7b08158.

[0076] [4] R. Su, R. Tiruvalam, A. J. Logsdail, Q. He, C.A. Downing, M.T. Jensen, N. Dimitratos, L. Kesavan, P.P. Wells, R. Bechstein, H.H. Jensen, S. Wendt, C.R.A. Catlow, C.J. Kiely, G.J. Hutchings, F. Besenbacher, Designer Titania-Supported Au-Pd Nanoparticles for Efficient Photocatalytic Hydrogen Production, ACS Nano. 8 (2014) 3490-3497. doi: 10.1021 / nn500963m.

[0077] [5] J.C. Colmenares Quintero, A. Magdziarz, Method of depositing metal nanoparticles on the surface of semiconductor materials and surface obtained by this process, PL 222050, 2015.

[0078] [6] J.C. Colmenares, P. Lisowski, D. Lomot, O. Chernyayeva, D. Lisovytskiy, Sonophotodeposition of Bimetallic Photocatalysts Pd-Au / TiO 2 : Application to Selective Oxidation of Methanol to Methyl Formate, ChemSusChem. 8 (2015) 1676-1685. doi: 10.1002 / cssc.201403125.

[0079] [7] K.S. Varma, R.J. Tayade, K.J. Shah, P.A. Joshi, A.D. Shukla, V.G. Gandhi, Photocatalytic degradation of pharmaceutical and pesticide compounds (PPCs) using doped TiO2 nanomaterials: A review, Water-Energy Nexus. 3 (2020) 46-61. doi:https: / / doi.org / 10.1016 / j.wen.2020.03.008.

[0080] [8] M.O. Miranda, W.E. Cabral Cavalcanti, F.F. Barbosa, J. de Sousa, F. da Silva, S.B.C. Pergher, T.P. Braga, Photocatalytic degradation of ibuprofen using titanium oxide: insights into the mechanism and preferential attack of radicals, RSC Adv. 11 (2021) 27720-27733. doi:10.1039 / D1 RA04340D.

Claims

Claims A flow reactor designed to remove heavy metal ions from water as a result of their sorption and to simultaneously remove biologically active substances dissolved in water, characterized in that it comprises a sorption-photocatalytic filling, the objects of which are agglomerates of modified halloysite particles with the composites of non-toxic and photoactive wide-gap materials located on their surface (the band gap is preferably 1.5-3.5 eV) decorated with transition metal particles, preferably from group 10 or 11 of the periodic system, wherein the efficiency of the process is caused by the mutual movement of the agglomerates and the stream of purified liquid and by the favorable conditions of light radiation access to the surface of the agglomerates. The reactor according to claim 1 , is characterized in that the composite filling of the photocatalytic reactor consists of the agglomerates of primary modified halloysite particles with an average equivalent diameter size of 50-100 micrometers, combined in the form of mesoporous structures with an average equivalent diameter of 1-10 mm and mesoporosity in the range of 50-70%. The reactor according to claim 1 , is characterized in that the halloysite particles contain on their surface nanoparticles of a wide-gap material, preferably a metal oxide, decorated with transition metal particles with sizes in the range of 10-150 nm for the composite of a wide-gap material / transition metal, wherein the mass proportion of the transition metal nanoparticles on the surface of the wide-gap material is 1-5%, and that of the wide-gap material / transition metal aggregates on the halloysite particles is a mass fraction in the range of 0.5 to 2%. The reactor according to claim 1 , is characterized in that it comprises a filling of composite halloysite particles selected from the stationary and fluidized one. The reactor according to claim 1 , is characterized in that it comprises light- transparent walls. The reactor according to claim 1 , is characterized in that it comprises walls that are non-transparent to light, wherein the light energy required for photocatalysis comes from a source selected from among the LED sources distributed uniformly throughout the reactor space and from an external LED source through a fiber optic system. The reactor according to claim 6, is characterized in that LED light has an electromagnetic radiation wavelength in the range of 360-550 nm.The reactor according to claim 6, is characterized in that LED light has a power of 10-40 W / 1 dm3of the suspended catalytic material. The reactor according to claim 6, is characterized in that the luminous flux of LED light with respect to the power unit of the source is 100-150 Im / W. The reactor according to claim 4, is characterized in that in the form of a stationary composite filling it comprises cylindrical containers filled with composite, with the walls transparent to LED light uniformly distributed throughout the volume of the reactor. The reactor according to claim 6, is characterized in that LED light is provided by means of optical fibers uniformly distributed within the intertubular space. The reactor according to claim 4, is characterized in that in the form of a fluidized composite filling LED light is provided by a uniform distribution of fiber optic sources throughout the reactor volume. The reactor according to claim 1 , is characterized in that the cross-section of the reactor is adapted to the set flow rate of purified water so that the linear flow rate is 0.02-0.6 m / s. The reactor according to claim 1 , is characterized in that it further comprises a prefiltration system disposed in front of it that is a non-woven tubular filter with an average porosity of 80%-90% and an average fiber diameter of 1-5 micrometers, wherein composite nanoparticles of transition metal oxides decorated with metal nanoparticles are placed on the surfaces of the non-woven filter elements. The reactor according to claim 1 , is characterized in that it further comprises an end filter disposed behind it that is a non-woven tubular filter having a porosity of 80%-90% and an average fiber diameter of 1-5 micrometers. The use of a flow reactor comprising a sorption-photocatalytic filling according to any of the claims 1 to 15 for removing dissolved biologically active substances, in particular drugs and opiate substances, as well as heavy metal ions, from water.

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