WO2022097072A1 - Photocatalytic additive - Google Patents
Photocatalytic additive Download PDFInfo
- Publication number
- WO2022097072A1 WO2022097072A1 PCT/IB2021/060247 IB2021060247W WO2022097072A1 WO 2022097072 A1 WO2022097072 A1 WO 2022097072A1 IB 2021060247 W IB2021060247 W IB 2021060247W WO 2022097072 A1 WO2022097072 A1 WO 2022097072A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- photocatalytic
- additive
- titanium
- electrodes
- photocatalytic additive
- Prior art date
Links
- 230000001699 photocatalysis Effects 0.000 title claims abstract description 56
- 239000000654 additive Substances 0.000 title claims abstract description 50
- 230000000996 additive effect Effects 0.000 title claims abstract description 49
- 239000002245 particle Substances 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims abstract description 21
- 239000000758 substrate Substances 0.000 claims abstract description 14
- 239000000470 constituent Substances 0.000 claims abstract description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 51
- 239000003973 paint Substances 0.000 claims description 27
- 239000010949 copper Substances 0.000 claims description 25
- 229910052802 copper Inorganic materials 0.000 claims description 18
- 239000011701 zinc Substances 0.000 claims description 13
- 230000000844 anti-bacterial effect Effects 0.000 claims description 12
- 229910052709 silver Inorganic materials 0.000 claims description 12
- 239000010936 titanium Substances 0.000 claims description 12
- 229910052725 zinc Inorganic materials 0.000 claims description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 10
- 239000002243 precursor Substances 0.000 claims description 10
- 229910052719 titanium Inorganic materials 0.000 claims description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 239000011572 manganese Substances 0.000 claims description 8
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 claims description 8
- 230000007062 hydrolysis Effects 0.000 claims description 7
- 238000006460 hydrolysis reaction Methods 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- 230000000840 anti-viral effect Effects 0.000 claims description 6
- 150000002739 metals Chemical class 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 229910052718 tin Inorganic materials 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 239000004332 silver Substances 0.000 claims description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 4
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 4
- 229910052681 coesite Inorganic materials 0.000 claims description 4
- 229910052906 cristobalite Inorganic materials 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229910052697 platinum Inorganic materials 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 235000012239 silicon dioxide Nutrition 0.000 claims description 4
- 229910052682 stishovite Inorganic materials 0.000 claims description 4
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052905 tridymite Inorganic materials 0.000 claims description 4
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 4
- 229910052721 tungsten Inorganic materials 0.000 claims description 4
- 239000010937 tungsten Substances 0.000 claims description 4
- -1 Silver ions Chemical class 0.000 claims description 3
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical group CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 239000004115 Sodium Silicate Substances 0.000 claims description 2
- LCKIEQZJEYYRIY-UHFFFAOYSA-N Titanium ion Chemical compound [Ti+4] LCKIEQZJEYYRIY-UHFFFAOYSA-N 0.000 claims description 2
- 239000002253 acid Substances 0.000 claims description 2
- XFVGXQSSXWIWIO-UHFFFAOYSA-N chloro hypochlorite;titanium Chemical compound [Ti].ClOCl XFVGXQSSXWIWIO-UHFFFAOYSA-N 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 2
- 238000011068 loading method Methods 0.000 claims description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 2
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 2
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 claims description 2
- CENHPXAQKISCGD-UHFFFAOYSA-N trioxathietane 4,4-dioxide Chemical compound O=S1(=O)OOO1 CENHPXAQKISCGD-UHFFFAOYSA-N 0.000 claims description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims 1
- 230000005855 radiation Effects 0.000 description 18
- 210000004027 cell Anatomy 0.000 description 11
- 150000002500 ions Chemical class 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 6
- 241000894006 Bacteria Species 0.000 description 5
- 241000588724 Escherichia coli Species 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 239000004065 semiconductor Substances 0.000 description 5
- 239000000725 suspension Substances 0.000 description 5
- 230000000845 anti-microbial effect Effects 0.000 description 4
- 238000011534 incubation Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 241001135549 Porcine epidemic diarrhea virus Species 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 230000001580 bacterial effect Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000000295 emission spectrum Methods 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 238000010422 painting Methods 0.000 description 3
- 239000011941 photocatalyst Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 2
- 241000589516 Pseudomonas Species 0.000 description 2
- 239000003139 biocide Substances 0.000 description 2
- 239000005312 bioglass Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 150000004679 hydroxides Chemical class 0.000 description 2
- 238000004452 microanalysis Methods 0.000 description 2
- 239000002086 nanomaterial Substances 0.000 description 2
- 238000003921 particle size analysis Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000000741 silica gel Substances 0.000 description 2
- 229910002027 silica gel Inorganic materials 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 239000004408 titanium dioxide Substances 0.000 description 2
- PBMVYDNBOIVHBO-DOFZRALJSA-N (5z,8z,11z,14z)-n-(4-nitrophenyl)icosa-5,8,11,14-tetraenamide Chemical compound CCCCC\C=C/C\C=C/C\C=C/C\C=C/CCCC(=O)NC1=CC=C([N+]([O-])=O)C=C1 PBMVYDNBOIVHBO-DOFZRALJSA-N 0.000 description 1
- PXMNMQRDXWABCY-UHFFFAOYSA-N 1-(4-chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)pentan-3-ol Chemical compound C1=NC=NN1CC(O)(C(C)(C)C)CCC1=CC=C(Cl)C=C1 PXMNMQRDXWABCY-UHFFFAOYSA-N 0.000 description 1
- 241000004176 Alphacoronavirus Species 0.000 description 1
- TWFZGCMQGLPBSX-UHFFFAOYSA-N Carbendazim Natural products C1=CC=C2NC(NC(=O)OC)=NC2=C1 TWFZGCMQGLPBSX-UHFFFAOYSA-N 0.000 description 1
- 241000711573 Coronaviridae Species 0.000 description 1
- 241000588722 Escherichia Species 0.000 description 1
- 241000233866 Fungi Species 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical group [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 206010034133 Pathogen resistance Diseases 0.000 description 1
- 239000005822 Propiconazole Substances 0.000 description 1
- 241000191940 Staphylococcus Species 0.000 description 1
- 241000191967 Staphylococcus aureus Species 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000005839 Tebuconazole Substances 0.000 description 1
- 241000700605 Viruses Species 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000002835 absorbance Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000004480 active ingredient Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 239000004599 antimicrobial Substances 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 239000003462 bioceramic Substances 0.000 description 1
- 230000003115 biocidal effect Effects 0.000 description 1
- 230000003592 biomimetic effect Effects 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- JNPZQRQPIHJYNM-UHFFFAOYSA-N carbendazim Chemical compound C1=C[CH]C2=NC(NC(=O)OC)=NC2=C1 JNPZQRQPIHJYNM-UHFFFAOYSA-N 0.000 description 1
- 239000006013 carbendazim Substances 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- WURGXGVFSMYFCG-UHFFFAOYSA-N dichlofluanid Chemical compound CN(C)S(=O)(=O)N(SC(F)(Cl)Cl)C1=CC=CC=C1 WURGXGVFSMYFCG-UHFFFAOYSA-N 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000000499 gel Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000008821 health effect Effects 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011081 inoculation Methods 0.000 description 1
- PUIYMUZLKQOUOZ-UHFFFAOYSA-N isoproturon Chemical compound CC(C)C1=CC=C(NC(=O)N(C)C)C=C1 PUIYMUZLKQOUOZ-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000013081 microcrystal Substances 0.000 description 1
- 239000011859 microparticle Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 238000007146 photocatalysis Methods 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 238000005381 potential energy Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- STJLVHWMYQXCPB-UHFFFAOYSA-N propiconazole Chemical compound O1C(CCC)COC1(C=1C(=CC(Cl)=CC=1)Cl)CN1N=CN=C1 STJLVHWMYQXCPB-UHFFFAOYSA-N 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000000527 sonication Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- IROINLKCQGIITA-UHFFFAOYSA-N terbutryn Chemical compound CCNC1=NC(NC(C)(C)C)=NC(SC)=N1 IROINLKCQGIITA-UHFFFAOYSA-N 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 210000001519 tissue Anatomy 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
- 238000001392 ultraviolet--visible--near infrared spectroscopy Methods 0.000 description 1
- 210000003501 vero cell Anatomy 0.000 description 1
- 230000003612 virological effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000003403 water pollutant Substances 0.000 description 1
- 229940043810 zinc pyrithione Drugs 0.000 description 1
- PICXIOQBANWBIZ-UHFFFAOYSA-N zinc;1-oxidopyridine-2-thione Chemical compound [Zn+2].[O-]N1C=CC=CC1=S.[O-]N1C=CC=CC1=S PICXIOQBANWBIZ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B01J35/39—
-
- B01J35/40—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
- B01J37/348—Electrochemical processes, e.g. electrochemical deposition or anodisation
Definitions
- Paints with antimicrobial properties are widely used, where the use of antimicrobials prolongs the life of the paint itself, especially by preserving water-based paints from mold attacks after opening and gives the surfaces to which said paints are applied antibacterial and antimicrobial properties for which there is a strong need. This need is strongly felt especially for painting facades, to prevent the onset of fungi and/or mold, as well as for painting interior environments such as hospitals, schools, premises for the preparation of food. Said paints are also widely used for painting objects and furnishings.
- Paints with biocide additives are widely used, such as Carbendazim, Dichlofluanid, Isoproturon, Propiconazole, Tebuconazole, Terbutryn, Zinc pyrithione.
- Said active ingredients are also effective on particularly resistant bacteria, such as E. Coli. However, they have been shown to be responsible for the onset of bacterial resistance, especially in the case of spore-forming bacteria.
- TiO2 titanium dioxide
- the photocatalytic properties of TiO2 have been investigated in recent years on a wide range of both atmospheric and water pollutants: alcohols, halides, aromatic hydrocarbons.
- the studies carried out have given promising results for organic acids, dyes, NOx and other. These properties have been applied in the removal of bacteria and harmful organic materials in water and air, as well as from surfaces in particular places such as medical centers.
- TiO2 exists in nature in amorphous and crystalline forms, the amorphous form is photocatalytically inactive.
- a further methodology used to increase TiO2 activity relates to the possibility of intervening on the electronic levels of the semiconductor, decreasing the energy of the band-gap in order to be able to use light at a lower frequency, such as the Visible one, to promote the electrons from the valence band (BV) to the conduction band (BC).
- BV valence band
- BC conduction band
- Such methodology sees the modification of the material through doping and consists of the introduction, during the synthesis step, of suitable precursors of elements capable of modulating the electronic properties thereof.
- the photocatalytic activity of anatase is strongly influenced by the dimension, but due to the toxicity shown by the nano dimension, many authors suggest the use of anatase in micrometric dimensions, although it decreases photocatalytic capacity.
- titanium dioxide is an n-type semiconductor; the Eg value of anatase is equal to 3.2 eV, that of rutile is 3.0 eV. From these values, it is clear from equation (1 ):
- h represents Planck’s constant, v the incident radiation frequency and c the speed of light in vacuum; the product he, constant term, is expressed in [eVxnm] and the wavelength A in nm.
- EP2188125B1 overcomes the pre-activation limit, describing an antibacterial photocatalytic paint comprising TiO2 in the form of anatase, having a crystalline particle size between 5 and 10 nm.
- an antibacterial photocatalytic paint comprising TiO2 in the form of anatase, having a crystalline particle size between 5 and 10 nm.
- the explosion in the use of nanomaterials has raised serious health and safety issues.
- US2006/0116279 describes an agglomerate comprising a larger particle (mother) which supports smaller particles (child).
- the smaller particles have an average diameter between 5 and 500 nm and contain TiO2 with photocatalytic activity.
- the agglomerate can be used in paints.
- a new nanostructured material with micrometric dimensions is obtained, which is suitable for producing crystals with dimensions, morphology, and structure such as to make the photocatalytic, anti-pollution, antibacterial and antiviral properties extraordinary.
- the photocatalytic additive according to the present invention is surprisingly capable of transforming inert substrates of any kind into a photocatalytic and antibacterial material by means of the biomimetic synthesis of nanosilicas functionalized with titanium-based precursors.
- Figure 1 X-ray diffraction spectrum of the product according to the present invention.
- FIG 2 (A) Scanning Electron Microscope (SEM) analysis of the product according to the present invention, representative images with two different magnifications; (B) representative spectrum obtained by subjecting the product according to the present invention to EDS spectroscopy (Energy Dispersive X-ray Spectrometry).
- Figure 3 Particle size analysis of the photocatalytic additive particles according to the present invention (gray line) and of the commercial anatase particles (gray line)
- Figure 4 Representative graphs of the abatement of the bacterial load on plates painted and inoculated with E. Coli (A), P. aeuriginosa (B) or S. aureus (C).
- Figure 5 (A) emission spectrum of the Philips PL-S 9W/2P BLB bulb used for radiating the samples; (B) emission spectrum of the 6500 K LED lighting system used for radiating the samples; concentration profiles for NO, NO2 and NOx (C) with UV radiation; (D) with visible radiation.
- the present invention first relates to a photocatalytic additive comprising particles consisting of TiO2, at least one substrate and, optionally, one or more metals, where said particles have a size between 10 and 100 micrometers, and said constituents, that is said TiO2, said at least one substrate and, where present, said one or more metals, are organized together in a homogeneous network.
- Said photocatalytic additive is a crystalline material which has the diffraction maxima characteristic of anatase ( Figure 1 ).
- said photocatalytic additive is doped with one or more of the metals selected from the group comprising carbon (C), nitrogen (N), tungsten (W), iron (Fe), silver (Ag), copper (Cu), zinc (Zn), tin (Sn) and/or manganese (Mn).
- the metals selected from the group comprising carbon (C), nitrogen (N), tungsten (W), iron (Fe), silver (Ag), copper (Cu), zinc (Zn), tin (Sn) and/or manganese (Mn).
- said substrate comprises SiO2.
- the SEM analysis of said additive loaded on a substrate according to the present invention shows that the same comprises clusters of substituted metal anatase microcrystals with a nanostructured hierarchical structure.
- a representative photo of an embodiment according to the present invention is shown in Figure 2A.
- the spectrum obtained with the EDS microanalysis ( Figure 2B) of a sample according to an embodiment of the present invention shows that the elemental composition of the particles consists of Ti, Zn, Cu, Si.
- the images of Figure 2A show that said clusters consist of a homogeneous network, where the components of the particles, which the EDS microanalysis has shown to be, in the embodiment under analysis, Ti, Zn, Cu and Si, are complexed together in a network.
- Each area of a particle according to the present invention is similar to the other, i.e., the particles according to the present invention do not comprise areas in which a first component is concentrated, linked to areas in which a second component is concentrated but each particle consists of a structured network which sees the presence of the different components of the particle itself.
- homogeneous network means a structure comprising at least two components, where said at least two components are organized together so as to form a complex which does not make them separable and clearly distinguishable within said structure.
- Figure 3 shows the comparison data between particles according to the present invention (gray line) and commercial anatase particles (black line).
- the graph shows that the particle size distribution of the particles according to the present invention is between about 10 and about 100 micrometers, while the anatase particles according to the prior art see a distribution between 1 and 100 micrometers.
- the particles according to the present invention having a particle size distribution such as to considerably limit the presence of particles with a diameter lower than 10 pm, obviate the problems of the particles of the background art specifically linked to the nanometric dimensions of the particles.
- the photocatalytic additive according to the present invention has shown advantageous antibacterial properties, as shown by the graphs of Figure 4. In fact, the photocatalytic additive has been shown to have a bactericidal effect on gram-positive and gram-negative bacteria. The photocatalytic additive according to the present invention has been shown to be capable of killing bacteria such as Escherichia, Pseudomonas and Staphylococcus.
- the additive has amazing antiviral properties.
- the photocatalytic additive has been shown to be effective against Coronavirus.
- the present invention further relates to the use of the photocatalytic additive described herein for the abatement of the bacterial and/or viral load. Said use is particularly advantageous where said additive is used in coatings, such as paints, which cover the surface of interest.
- said additive is advantageously used in cosmetic formulations, food compositions and textile items where it has proved useful in the antibacterial, antimicrobial, and antiviral function thereof.
- the present invention further relates to a method for obtaining a photocatalytic additive comprising:
- the electrodes in said electrolytic cell comprising two electrodes preferably selected from Ti/Ti, Sn/Sn, Cu/Cu, Cu/Pt, Cu/Ag, Cu/Zn, Zn/Ag, Zn/Pt, Ag/Pt.
- said polarity reversal of the electrodes occurs with a frequency of about 1 or more times every 10 minutes, or 1 or more times every 15 minutes.
- said polarity reversal of the electrodes occurs with a frequency of about 1 time every 10 minutes, or 1 time every 15 minutes.
- said precursor is a titanium-based precursor, for example selected from the group comprising titanium (IV) oxysulfate, titanium tetrachloride, titanium tetraisopropoxide, titanium isopropoxide, titanium oxychloride.
- said precursor is subjected to acid or basic hydrolysis before being dripped into said electrochemical cell.
- said hydrolysis product of the titanium-based precursor is dripped into said electrochemical cell so as to obtain a suspension of Ti ions in a concentration between 5 - 15% (w/V), preferably about 12% (w/V).
- a photocatalytic additive doped with chemical elements or oxides such as carbon (C), nitrogen (N), tungsten (W), iron (Fe), Silver (Ag), copper (Cu), Zinc (Zn), Tin (Sn), Manganese (Mn)
- said method further comprises the addition in said electrochemical cell of said metals, preferably in the form of hydroxides.
- Zn, Cu and/or Ag ions are added.
- said Zn ions are added in an amount between 1 and 3% (w/V), preferably about 1 % (w/V)
- said Cu ions are added in an amount between 1 and 3% (w/V), preferably about 1 % (w/V)
- said Ag ions are added in an amount between 0.05 and 0.5% (w/V), preferably about 0.05% (w/V).
- said substrate comprises SiC>2, preferably it is a silicate, for example tetraethyl orthosilicate (TECS), or sodium silicate.
- said substrate is bioglass, or is a xerogel or is a silica gel.
- bioglass means a bioceramic material which shows biocompatibility with cellular tissue and predisposition for the formation of a biological bond with bone tissue.
- the gel form promotes the maintenance of the microparticles in suspension.
- the present invention further relates to a photocatalytic additive obtained by the process according to the present invention.
- the procedure according to the present invention advantageously allows enriching the hydrolysis product with Cu 2+ ions conveniently released by the electrode.
- the authors of the present invention have demonstrated that the polarity inversion of the electrodes makes the metal ions which interact with hydrolyzed Ti always available in suspension.
- Said additive is conveniently stored and used in powder form.
- said powder is rehydrated before use, for example before adding the additive in a paint.
- Example 1 obtaining a photocatalytic additive
- a silica gel was loaded into an electrolytic cell comprising two Cu/Cu electrodes.
- the hydrolysis product of a titanium-based precursor was dripped therein, so as to have about 5% w/V of titanium ions in suspension.
- Zn and Ag ions were also added in the form of hydroxides to said electrolytic cell, so as to have a concentration of Zn ions equal to about 1 % w/V and a concentration of Ag ions equal to about 0.05% (p/V) in suspension.
- a voltage of 12-24 volts and a current of 0.01-0.10 A/cm 2 was applied to said electrodes, keeping under stirring for 3 hours. During said stirring, the polarity of said two electrodes was reversed every 12 minutes.
- the voltage was removed, and the product obtained was heated to about 130°C, at a maximum pressure of 5 bar, for 3 hours.
- the product obtained is the photocatalytic additive.
- Example 2 obtaining paint comprising the photocatalytic additive
- the photocatalytic additive obtained as in example 1 was added to a water-based paint not comprising biocides in an amount equal to 5% w/V (the paint was called BLG-5%).
- the photocatalytic additive obtained as in example 1 is rehydrated and then added to the same paint as above in an amount equal to 5% w/V.
- the paint with photocatalytic additive obtained as in example 2 by adding 5% w/V of the additive according to the present invention to a water-based paint, BLG6-5%, was tested for antibacterial activity.
- a control the same paint not added with the photocatalytic additive according to the present invention was used.
- the samples consisted of a 50 x 50 mm steel plate on which a 1 mm thick film of the control or paint according to the invention was deposited.
- the radiation was provided by a LED or UV bulb 0.25 mW/cm 2 , having the spectrum for an exposure time shown in Figure 5, of 4, 8 and 24 hours.
- Escherichia coli, Staphylococcus aureus and Pseudomonas aeuriginosa were used, inoculating 8.6 x 10 5 CFU/ml
- Example 4 photocatalytic activity, abatement of nitric oxide
- the NO abatement tests were performed with the tangential flow method, in accordance with the UNI 11484-2013 standard. The tests were carried out with a simplified procedure, i.e., when the stability condition of the concentrations measured under radiation was reached or the maximum radiation time of 180 minutes was reached, the flow velocity inside the reactor was not changed, thus ending the test under these conditions. The samples were studied under both UV and visible radiation. io The determination of the NO/NO2 content in the measurement flows was carried out by means of an APNA 370 chemiluminescence meter. The measurement reactor had an inner volume of 3.6 dm 3 . The mixing inside the reactor was ensured by a compact axial fan EBMPAPST 612 JH (dimensions 60x60x32 mm) which provides a nominal flow of 70 m 3 tr 1 .
- the UV radiation took place by means of a set of two Philips PL-S 9W/2P BLB fluorescent bulbs having a significant UV emission, the emission spectrum of which is shown in Figure 5A.
- the intensity of the radiation incident on the sample was 10 W rrr 2 between 290 and 400 nm.
- the light intensity was evaluated by spectroradiometry using an Ocean Optics USB2000+UV-VIS spectrophotometer provided with an optical fiber with a diameter of 400 pm and a length equal to 30 cm provided with a cosine corrector (Ocean Optics CC-3-UV-T, PTFE optical diffuser, spectral range 200-2500 nm, outer diameter 6.35 mm, field of vision 180°).
- the spectroradiometer was calibrated with an Ocean Optics DH-2000-CAL Deuterium-Halogen Light Sources lamp for UV-Vis-NIR measurements which was itself calibrated in absolute radiance by the vendor (Radiometric Calibration Standard UV-NIR, calibration certificate # 2162).
- the tested samples were two 10 cm x 10 cm x 9 mm ceramic tiles painted with BLG6-5% paint, as in example 2. One sample was used for the test with UV radiation, the other for the test with visible radiation. The samples were not exposed to any pre-treatment.
- the tested samples showed a significant reduction of NO both under UV radiation and under visible radiation.
- an NO reduction of 810 pg rrr 2 tr 1 was observed with UV radiation and 580 pg m’ 2 h’ 1 with visible radiation.
- the paint with photocatalytic additive obtained as in example 2 by adding 5% w/V of the additive according to the present invention to a water-based paint, BLG6-5%, was tested for antiviral activity.
- the Plaque Reduction Neutralization Test (PRNT) against porcine coronavirus (PEDV) was conducted. The test was conducted as described in Wang S et al. J Immunol Methods 2005, 301 : 21-30. Briefly, PEDV was dripped onto the sample surface, and, after an incubation of 30 or 60 minutes, samples were collected in which the permanence of the virus in Vero cells was assessed. After incubation at 37°C for 3 days, the infected cells were fixed and labeled.
- PRNT Plaque Reduction Neutralization Test
- PEDV porcine coronavirus
- the efficacy of the product was derived by observing the number of PEDV plaques in each sample, compared with the control (without BLG6 additive). The results show an efficiency of BLG6-5% equal to 89.58% after 30 minutes incubation and 99.21 % after 60 minutes incubation.
- the particle size of the photocatalytic additive particles according to the present invention was analyzed by laser diffraction in accordance with ISO 13320: 2020.
- a Mastersizer 3000 (Malvern-Panalytical) was used.
- a sample of BGL6 particles, obtained as in example 1 , and for comparative purposes, a sample of commercial anatase nanoparticles were analyzed.
- Nanoparticles according to the invention or control were dispersed in deionized water and the dispersion was added to the sampler. Measurements were taken after sonication with 100% internal ultrasound for 10 minutes.
- the analysis parameters are the following:
- Circulation rate 2000 rpm
- D(50) particle size expressed in pm below and above which 50% of the sample resides. Represents the median of the distribution.
- D(90) particle size expressed in pm below which 90% of the sample resides.
Abstract
The present invention relates to a method for obtaining a photocatalytic additive and to said photocatalytic additive, where said photocatalytic additive comprises particles comprising T1O2 and at least one substrate as constituents, where the size of said particles is between 10 and 100 micrometers, where said constituents are organized together in a homogeneous network.
Description
Photocatalytic additive
Background art
Paints with antimicrobial properties are widely used, where the use of antimicrobials prolongs the life of the paint itself, especially by preserving water-based paints from mold attacks after opening and gives the surfaces to which said paints are applied antibacterial and antimicrobial properties for which there is a strong need. This need is strongly felt especially for painting facades, to prevent the onset of fungi and/or mold, as well as for painting interior environments such as hospitals, schools, premises for the preparation of food. Said paints are also widely used for painting objects and furnishings.
Paints with biocide additives are widely used, such as Carbendazim, Dichlofluanid, Isoproturon, Propiconazole, Tebuconazole, Terbutryn, Zinc pyrithione. Said active ingredients are also effective on particularly resistant bacteria, such as E. Coli. However, they have been shown to be responsible for the onset of bacterial resistance, especially in the case of spore-forming bacteria.
Alternatively, paints with photocatalytic properties have been used.
Among the most studied materials in photocatalysis, titanium dioxide, TiO2, has aroused the greatest interest, as it combines important features such as long-term stability and low toxicity for the biosphere, with good photocatalytic activity with respect to other semiconductors. The photocatalytic properties of TiO2 have been investigated in recent years on a wide range of both atmospheric and water pollutants: alcohols, halides, aromatic hydrocarbons. The studies carried out have given promising results for organic acids, dyes, NOx and other. These properties have been applied in the removal of bacteria and harmful organic materials in water and air, as well as from surfaces in particular places such as medical centers.
TiO2 exists in nature in amorphous and crystalline forms, the amorphous form is photocatalytically inactive. There are three natural crystalline forms of TiC : anatase, rutile and brookite. Anatase and rutile have a tetragonal structure, while the brookite structure is orthorhombic. Brookite is less
common than the previous two crystal polymorphs and is much more difficult to obtain. Anatase and rutile are photocatalytically active, while brookite has never been tested for photocatalytic activity. Pure anatase is more active as a photocatalyst with respect to rutile, probably because it has a higher negative potential at the edge of the conductive band, which means higher photo-generation electron potential energy and also due to a higher number of -OH groups on the surface thereof.
The presence of SiO2, especially if mesoporous, to the extent of 5% mol, improves the photocatalytic activities due to an increase in surface area. A further methodology used to increase TiO2 activity relates to the possibility of intervening on the electronic levels of the semiconductor, decreasing the energy of the band-gap in order to be able to use light at a lower frequency, such as the Visible one, to promote the electrons from the valence band (BV) to the conduction band (BC). Such methodology sees the modification of the material through doping and consists of the introduction, during the synthesis step, of suitable precursors of elements capable of modulating the electronic properties thereof. The photocatalytic activity of anatase is strongly influenced by the dimension, but due to the toxicity shown by the nano dimension, many authors suggest the use of anatase in micrometric dimensions, although it decreases photocatalytic capacity.
From an electronic point of view, titanium dioxide is an n-type semiconductor; the Eg value of anatase is equal to 3.2 eV, that of rutile is 3.0 eV. From these values, it is clear from equation (1 ):
Eg=h v =hc/ A =1240/ A (1) that the anatase is "activated" by light having a wavelength A < 388 nm, i.e., from the UVA portion of the electromagnetic spectrum. In equation (1 ), h represents Planck’s constant, v the incident radiation frequency and c the speed of light in vacuum; the product he, constant term, is expressed in [eVxnm] and the wavelength A in nm.
Despite the advantages of the existing photocatalytic coatings based on TiO2, there is room for improvement in the art. In order to exert the effect thereof, some photocatalysts need to be pre-activated, for example by
washing with water, adding a process step which makes the application of paints thus formulated inconvenient.
EP2188125B1 overcomes the pre-activation limit, describing an antibacterial photocatalytic paint comprising TiO2 in the form of anatase, having a crystalline particle size between 5 and 10 nm. However, the explosion in the use of nanomaterials has raised serious health and safety issues. One of these concerns the health effects of respirable nanoparticles.
US2006/0116279 describes an agglomerate comprising a larger particle (mother) which supports smaller particles (child). The smaller particles have an average diameter between 5 and 500 nm and contain TiO2 with photocatalytic activity. The agglomerate can be used in paints.
Therefore, there is a strong need to improve the photocatalysts currently available, in particular for the application thereof in the field of paints.
Description of the invention
In the present invention, with an innovative process which uses the physical conditions of an electrochemical process, a new nanostructured material with micrometric dimensions is obtained, which is suitable for producing crystals with dimensions, morphology, and structure such as to make the photocatalytic, anti-pollution, antibacterial and antiviral properties extraordinary.
Therefore, the photocatalytic additive according to the present invention is surprisingly capable of transforming inert substrates of any kind into a photocatalytic and antibacterial material by means of the biomimetic synthesis of nanosilicas functionalized with titanium-based precursors. Description of the drawings
Figure 1 : X-ray diffraction spectrum of the product according to the present invention.
Figure 2: (A) Scanning Electron Microscope (SEM) analysis of the product according to the present invention, representative images with two different magnifications; (B) representative spectrum obtained by subjecting the product according to the present invention to EDS spectroscopy (Energy Dispersive X-ray Spectrometry).
Figure 3: Particle size analysis of the photocatalytic additive particles according to the present invention (gray line) and of the commercial anatase particles (gray line)
Figure 4: Representative graphs of the abatement of the bacterial load on plates painted and inoculated with E. Coli (A), P. aeuriginosa (B) or S. aureus (C).
Figure 5: (A) emission spectrum of the Philips PL-S 9W/2P BLB bulb used for radiating the samples; (B) emission spectrum of the 6500 K LED lighting system used for radiating the samples; concentration profiles for NO, NO2 and NOx (C) with UV radiation; (D) with visible radiation.
Detailed description
The present invention first relates to a photocatalytic additive comprising particles consisting of TiO2, at least one substrate and, optionally, one or more metals, where said particles have a size between 10 and 100 micrometers, and said constituents, that is said TiO2, said at least one substrate and, where present, said one or more metals, are organized together in a homogeneous network.
Said photocatalytic additive is a crystalline material which has the diffraction maxima characteristic of anatase (Figure 1 ).
In an embodiment, said photocatalytic additive is doped with one or more of the metals selected from the group comprising carbon (C), nitrogen (N), tungsten (W), iron (Fe), silver (Ag), copper (Cu), zinc (Zn), tin (Sn) and/or manganese (Mn).
In a further embodiment, said substrate comprises SiO2.
The SEM analysis of said additive loaded on a substrate according to the present invention shows that the same comprises clusters of substituted metal anatase microcrystals with a nanostructured hierarchical structure. A representative photo of an embodiment according to the present invention is shown in Figure 2A. The spectrum obtained with the EDS microanalysis (Figure 2B) of a sample according to an embodiment of the present invention shows that the elemental composition of the particles consists of Ti, Zn, Cu, Si.
The images of Figure 2A show that said clusters consist of a homogeneous network, where the components of the particles, which the EDS microanalysis has shown to be, in the embodiment under analysis, Ti, Zn, Cu and Si, are complexed together in a network. Each area of a particle according to the present invention is similar to the other, i.e., the particles according to the present invention do not comprise areas in which a first component is concentrated, linked to areas in which a second component is concentrated but each particle consists of a structured network which sees the presence of the different components of the particle itself.
Therefore, the term "homogeneous network" means a structure comprising at least two components, where said at least two components are organized together so as to form a complex which does not make them separable and clearly distinguishable within said structure.
The particle size was analyzed by laser diffraction. In particular, Figure 3 shows the comparison data between particles according to the present invention (gray line) and commercial anatase particles (black line). The graph shows that the particle size distribution of the particles according to the present invention is between about 10 and about 100 micrometers, while the anatase particles according to the prior art see a distribution between 1 and 100 micrometers.
Advantageously, the particles according to the present invention, having a particle size distribution such as to considerably limit the presence of particles with a diameter lower than 10 pm, obviate the problems of the particles of the background art specifically linked to the nanometric dimensions of the particles.
The photocatalytic additive according to the present invention has shown advantageous antibacterial properties, as shown by the graphs of Figure 4. In fact, the photocatalytic additive has been shown to have a bactericidal effect on gram-positive and gram-negative bacteria. The photocatalytic additive according to the present invention has been shown to be capable of killing bacteria such as Escherichia, Pseudomonas and Staphylococcus.
Furthermore, the additive has amazing antiviral properties. In particular, the
photocatalytic additive has been shown to be effective against Coronavirus.
Therefore, the present invention further relates to the use of the photocatalytic additive described herein for the abatement of the bacterial and/or viral load. Said use is particularly advantageous where said additive is used in coatings, such as paints, which cover the surface of interest.
In a further embodiment, said additive is advantageously used in cosmetic formulations, food compositions and textile items where it has proved useful in the antibacterial, antimicrobial, and antiviral function thereof.
The present invention further relates to a method for obtaining a photocatalytic additive comprising:
- providing an electrolytic cell;
- loading a substrate having a high surface area and free hydroxyl groups into said electrolytic cell;
- dripping the precursor of a semiconductor or the hydrolysis product thereof into said electrolytic cell;
- applying a voltage of 12-24 volts and a current of 0.01-0.10 A/cm2 to the electrodes of said electrolytic cell and keep stirring for a time between 1 and 8 hours, preferably between 2 and 4 hours, where, during said stirring, the polarity of said electrodes is frequently reversed;
- subjecting the preparation to heating at 120-140 °C, with a maximum pressure of 5 bar, for a time between 1 and 8 hours, preferably between 2 and 4 hours, obtaining said photocatalytic additive.
In an embodiment, the electrodes in said electrolytic cell comprising two electrodes preferably selected from Ti/Ti, Sn/Sn, Cu/Cu, Cu/Pt, Cu/Ag, Cu/Zn, Zn/Ag, Zn/Pt, Ag/Pt.
In an embodiment, said polarity reversal of the electrodes occurs with a frequency of about 1 or more times every 10 minutes, or 1 or more times every 15 minutes.
In an embodiment, said polarity reversal of the electrodes occurs with a frequency of about 1 time every 10 minutes, or 1 time every 15 minutes.
In an embodiment, said precursor is a titanium-based precursor, for example
selected from the group comprising titanium (IV) oxysulfate, titanium tetrachloride, titanium tetraisopropoxide, titanium isopropoxide, titanium oxychloride.
In an embodiment, said precursor is subjected to acid or basic hydrolysis before being dripped into said electrochemical cell.
In an embodiment, said hydrolysis product of the titanium-based precursor is dripped into said electrochemical cell so as to obtain a suspension of Ti ions in a concentration between 5 - 15% (w/V), preferably about 12% (w/V).
In an embodiment, to obtain a photocatalytic additive doped with chemical elements or oxides, such as carbon (C), nitrogen (N), tungsten (W), iron (Fe), Silver (Ag), copper (Cu), Zinc (Zn), Tin (Sn), Manganese (Mn), said method further comprises the addition in said electrochemical cell of said metals, preferably in the form of hydroxides.
In a preferred form, Zn, Cu and/or Ag ions are added. In an embodiment, said Zn ions are added in an amount between 1 and 3% (w/V), preferably about 1 % (w/V), said Cu ions are added in an amount between 1 and 3% (w/V), preferably about 1 % (w/V), said Ag ions are added in an amount between 0.05 and 0.5% (w/V), preferably about 0.05% (w/V).
In an embodiment, said substrate comprises SiC>2, preferably it is a silicate, for example tetraethyl orthosilicate (TECS), or sodium silicate. In an embodiment, said substrate is bioglass, or is a xerogel or is a silica gel.
In the context of the present invention, bioglass means a bioceramic material which shows biocompatibility with cellular tissue and predisposition for the formation of a biological bond with bone tissue.
Advantageously, the gel form promotes the maintenance of the microparticles in suspension.
The present invention further relates to a photocatalytic additive obtained by the process according to the present invention.
The procedure according to the present invention advantageously allows enriching the hydrolysis product with Cu2+ ions conveniently released by the electrode. In fact, the authors of the present invention have demonstrated that the polarity inversion of the electrodes makes the metal ions which
interact with hydrolyzed Ti always available in suspension.
The extraordinary properties of the photocatalytic additive according to the present invention, illustrated in the following examples, given purely by way of example and not to be understood in any way as limiting the scope of the present invention, the scope of protection of which is defined by the claims, make it applicable both directly to the surfaces to be treated and as an additive in paints. Said antimicrobial and antibacterial properties have proved to be particularly advantageous both in conditions of natural or artificial light, and in conditions of darkness.
Said additive is conveniently stored and used in powder form. In an embodiment, said powder is rehydrated before use, for example before adding the additive in a paint.
The following examples have the sole purpose of better describing the invention, the scope of which is defined by the following claims.
Examples
Example 1 : obtaining a photocatalytic additive
A silica gel was loaded into an electrolytic cell comprising two Cu/Cu electrodes. The hydrolysis product of a titanium-based precursor was dripped therein, so as to have about 5% w/V of titanium ions in suspension. Zn and Ag ions were also added in the form of hydroxides to said electrolytic cell, so as to have a concentration of Zn ions equal to about 1 % w/V and a concentration of Ag ions equal to about 0.05% (p/V) in suspension.
A voltage of 12-24 volts and a current of 0.01-0.10 A/cm2 was applied to said electrodes, keeping under stirring for 3 hours. During said stirring, the polarity of said two electrodes was reversed every 12 minutes.
At the end of said stirring, the voltage was removed, and the product obtained was heated to about 130°C, at a maximum pressure of 5 bar, for 3 hours. The product obtained is the photocatalytic additive.
Example 2: obtaining paint comprising the photocatalytic additive
The photocatalytic additive obtained as in example 1 , called BLG6, was added to a water-based paint not comprising biocides in an amount equal to 5% w/V (the paint was called BLG-5%). In a further embodiment, the
photocatalytic additive obtained as in example 1 is rehydrated and then added to the same paint as above in an amount equal to 5% w/V.
Example 3: antibacterial activity
The paint with photocatalytic additive obtained as in example 2, by adding 5% w/V of the additive according to the present invention to a water-based paint, BLG6-5%, was tested for antibacterial activity. As a control, the same paint not added with the photocatalytic additive according to the present invention was used. The samples consisted of a 50 x 50 mm steel plate on which a 1 mm thick film of the control or paint according to the invention was deposited.
The method for measuring the antibacterial activity of photocatalytic semiconductor materials ISO 27447:2019 was followed.
The radiation was provided by a LED or UV bulb 0.25 mW/cm2, having the spectrum for an exposure time shown in Figure 5, of 4, 8 and 24 hours. Escherichia coli, Staphylococcus aureus and Pseudomonas aeuriginosa were used, inoculating 8.6 x 105 CFU/ml
The results obtained following inoculation with E. Coli and exposure to LED light are shown in table 1 .
LED light are shown in Table 2.
The experiment was repeated, with the only variation being that the illumination was provided by UV light. The results are shown in Figure 4A for E. coli, in Figure 4B for P. aeuriginosa, in Figure 4C for S. aureus.
The data as a whole show that the paint added with the photocatalytic additive according to the present invention leads, in all the conditions tested, both after LED radiation and after UV radiation, to a complete killing of the 3 bacterial strains tested over the period of 24 hours.
Example 4: photocatalytic activity, abatement of nitric oxide
The NO abatement tests were performed with the tangential flow method, in accordance with the UNI 11484-2013 standard. The tests were carried out with a simplified procedure, i.e., when the stability condition of the concentrations measured under radiation was reached or the maximum radiation time of 180 minutes was reached, the flow velocity inside the reactor was not changed, thus ending the test under these conditions. The samples were studied under both UV and visible radiation. io
The determination of the NO/NO2 content in the measurement flows was carried out by means of an APNA 370 chemiluminescence meter. The measurement reactor had an inner volume of 3.6 dm3. The mixing inside the reactor was ensured by a compact axial fan EBMPAPST 612 JH (dimensions 60x60x32 mm) which provides a nominal flow of 70 m3 tr1.
The UV radiation took place by means of a set of two Philips PL-S 9W/2P BLB fluorescent bulbs having a significant UV emission, the emission spectrum of which is shown in Figure 5A. The intensity of the radiation incident on the sample was 10 W rrr2 between 290 and 400 nm.
In the case of visible radiation, notwithstanding the UNI 11484 standard, a LED illuminator (6500 K) with no UV emission was used. The spectrum of such a source is shown in Figure 5B. The radiance on the sample surface was 250 W m2 between 400 and 800 nm.
The light intensity was evaluated by spectroradiometry using an Ocean Optics USB2000+UV-VIS spectrophotometer provided with an optical fiber with a diameter of 400 pm and a length equal to 30 cm provided with a cosine corrector (Ocean Optics CC-3-UV-T, PTFE optical diffuser, spectral range 200-2500 nm, outer diameter 6.35 mm, field of vision 180°). The spectroradiometer was calibrated with an Ocean Optics DH-2000-CAL Deuterium-Halogen Light Sources lamp for UV-Vis-NIR measurements which was itself calibrated in absolute radiance by the vendor (Radiometric Calibration Standard UV-NIR, calibration certificate # 2162).
The tested samples were two 10 cm x 10 cm x 9 mm ceramic tiles painted with BLG6-5% paint, as in example 2. One sample was used for the test with UV radiation, the other for the test with visible radiation. The samples were not exposed to any pre-treatment.
The evolution of the NO and NO2 concentrations during the test is shown in Figure 5, where panel C shows data with exposure to UV light, panel D shows data with exposure to visible light.
The tested samples showed a significant reduction of NO both under UV radiation and under visible radiation. In particular, in the tested conditions an NO reduction of 810 pg rrr2 tr1 was observed with UV radiation and 580 pg
m’2 h’1 with visible radiation.
Example 5: antiviral activity
The paint with photocatalytic additive obtained as in example 2, by adding 5% w/V of the additive according to the present invention to a water-based paint, BLG6-5%, was tested for antiviral activity. The Plaque Reduction Neutralization Test (PRNT) against porcine coronavirus (PEDV) was conducted. The test was conducted as described in Wang S et al. J Immunol Methods 2005, 301 : 21-30. Briefly, PEDV was dripped onto the sample surface, and, after an incubation of 30 or 60 minutes, samples were collected in which the permanence of the virus in Vero cells was assessed. After incubation at 37°C for 3 days, the infected cells were fixed and labeled. The efficacy of the product was derived by observing the number of PEDV plaques in each sample, compared with the control (without BLG6 additive). The results show an efficiency of BLG6-5% equal to 89.58% after 30 minutes incubation and 99.21 % after 60 minutes incubation.
Example 6: particle size analysis
The particle size of the photocatalytic additive particles according to the present invention was analyzed by laser diffraction in accordance with ISO 13320: 2020. A Mastersizer 3000 (Malvern-Panalytical) was used. A sample of BGL6 particles, obtained as in example 1 , and for comparative purposes, a sample of commercial anatase nanoparticles were analyzed.
Nanoparticles according to the invention or control were dispersed in deionized water and the dispersion was added to the sampler. Measurements were taken after sonication with 100% internal ultrasound for 10 minutes. The analysis parameters are the following:
Calculation theory: Mie
Sample Refractive index: 1 .55 - (blue light: 1 .66)
Sample Absorbance index: 0.01
Dispersant Refractive index: 1.330
Darkness: 10-20 %
Circulation rate: 2000 rpm
Number of measurements: 6
Table 4 shows the results obtained.
D(10): particle size expressed in pm below which 10% of the sample resides.
D(50): particle size expressed in pm below and above which 50% of the sample resides. Represents the median of the distribution.
D(90): particle size expressed in pm below which 90% of the sample resides.
Claims
1. A photocatalytic additive comprising particles comprising TiO2 and at least one substrate as constituents, wherein the size of said particles is between 10 and 100 micrometers, wherein said constituents are organized together in a homogeneous network.
2. A photocatalytic additive according to claim 1 , wherein said TiO2 is in the form of anatase.
3. A photocatalytic additive according to claim 1 or 2, wherein said at least one substrate comprises SiO2.
4. A photocatalytic additive according to one of claims 1 to 3, doped with one or more of the metals selected from the group comprising carbon (C), nitrogen (N), tungsten (W), iron (Fe), silver (Ag), copper (Cu), zinc (Zn), tin (Sn) and/or manganese (Mn).
5. A method for obtaining a photocatalytic additive comprising:
- providing at least one electrolytic cell comprising two electrodes, wherein said two electrodes are preferably selected from the group comprising Cu/Cu, Cu/Pt, Cu/Ag, Cu/Zn, Zn/Ag, Zn/Pt, Ag/Pt;
- loading a substrate having a high surface area and free hydroxyl groups into said electrolytic cell;
- proceeding with acid or basic hydrolysis of a titanium-based precursor, wherein said precursor is selected from the group comprising titanium (IV) oxysulfate, titanium tetrachloride, titanium tetraisopropoxide, titanium isopropoxide, titanium oxychloride;
- dripping the hydrolysis product into said electrolytic cell;
- applying a voltage of 12-24 volts and a current of 0.01-0.10 A/cm2 to the electrodes of said electrolytic cell and keep stirring for a time between 1 and 8 hours, preferably between 2 and 4 hours, where, during said stirring, the polarity of said electrodes is frequently reversed;
- subjecting the preparation to heating at 120-140 °C, with a maximum pressure of 5 bar, for a time between 1 and 8 hours, preferably
between 2 and 4 hours, obtaining said photocatalytic additive.
6. A method according to claim 5, wherein one or more of the metals selected from the group comprising: carbon (C), nitrogen (N), tungsten (W), Iron (Fe), Silver (Ag), copper (Cu), Zinc (Zn), Tin (Sn), Manganese (Mn) are added to said at least one electrochemical cell.
7. A method according to claim 5, wherein Zinc, Copper and Silver ions are added to said electrochemical cell.
8. A method according to one of claims 5 to 7, wherein said substrate comprises SiO2.
9. A method according to one of claims 5 to 7, wherein said substrate is tetraethyl orthosilicate (TEOS) and/or sodium silicate.
10. A method according to one of claims 5 to 9, wherein said polarity reversal of the electrodes occurs with a frequency of about once every 10 minutes, or once every 15 minutes.
11. A photocatalytic additive obtained according to the method of one of claims 5 to 10.
12.A photocatalytic composition comprising the photocatalytic additive according to one of claims 1 -4 or 11 .
13. A photocatalytic composition according to claim 12 which is a paint.
14. Use of the additive according to one of claims 1-4 or 11 to introduce an antibacterial - antiviral photocatalytic activity into compositions.
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PETICA AURORA ET AL: "Synthesis and characterization of silver-titania nanocomposites prepared by electrochemical method with enhanced photocatalytic characteristics, antifungal and antimicrobial activity", vol. 8, no. 1, 1 January 2019 (2019-01-01), BR, pages 41 - 53, XP055815980, ISSN: 2238-7854, Retrieved from the Internet <URL:http://dx.doi.org/10.1016/j.jmrt.2017.09.009> DOI: 10.1016/j.jmrt.2017.09.009 * |
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