CN108943235B

CN108943235B - Preparation of Fe on wood surface3+Doped TiO 22/SiO2Method for laminating films

Info

Publication number: CN108943235B
Application number: CN201810805369.8A
Authority: CN
Inventors: 符韵林; 玄路宁; 刘志高
Original assignee: Guangxi University
Current assignee: Guangxi University
Priority date: 2018-07-20
Filing date: 2018-07-20
Publication date: 2021-03-05
Anticipated expiration: 2038-07-20
Also published as: CN108943235A

Abstract

The invention discloses a method for preparing Fe on the surface of wood³⁺Doped TiO 2₂/SiO₂A method for the lamination of a membrane, comprising the following operative steps: (1) preparing titanium sol; (2) preparing silica sol; (3) fe³⁺Doping: mixing the prepared titanium sol and the prepared silica sol uniformly, and adding Ti⁴⁺Based on Fe³⁺：Ti⁴⁺Adding ferric nitrate according to the proportion of 1: 10-40, heating and stirring for 30min to obtain fully mixed Fe³⁺Doping sol; (4) wood impregnation: putting wood into the Fe prepared in the step (3)³⁺And (5) dipping the doped sol to obtain the nano-silver/nano-silver. The invention utilizes sol-gel technology to prepare surface-loaded Fe³⁺Doped TiO 2₂/SiO₂The eucalyptus of the composite film limits the silicon-titanium ratio and the iron ion doping amount, and the wood is impregnated in a mode, so that pollutants can be degraded, the self-cleaning effect is achieved, the application field of the artificial board is expanded, and the added value of the product is improved.

Description

Preparation of Fe on wood surface3+Doped TiO 22/SiO2Method for laminating films

Technical Field

The invention relates to a preparation method of a composite film, in particular to a method for preparing Fe on the surface of wood³⁺Doped TiO 2₂/SiO₂A method of composite membrane.

Background

The total wood consumption of 2016 about 60941 km³The yield of forest products such as paper making, wooden furniture, artificial boards and the like is first in the world. Eucalyptus as an artificial forest fast growing wood has the advantages of high yield, consistent material quality and the like, can effectively relieve the problem of raw material shortage in the wood processing industry, but limits the application range of the eucalyptus due to poor material properties, is more used for producing core layer raw materials of paper pulp, fiberboards and laminated veneer lumber at present, and has low additional value. The sol-gel technology is a process for obtaining oxides or other compounds from metal organic compounds, metal inorganic compounds or mixtures through hydrolysis and polycondensation processes, gradual gelation and corresponding post-treatment. Some scholars at home and abroad successfully prepare the wood composite material by adopting the method. In 1992, Saka et al and Ogiso et al led to the adoption of sol-gel method for preparing wood/inorganic composite materials, which had good dimensional stability and flame retardancy; li Jian et al SiO₂Loading on the surface of wood to prepare modified aerogel; jiangze wineHui et al, Wang Xicheng et al and charming et al also get corresponding achievements.

As a material for indoor and furniture, wood is closer to daily life of people, whether wood can be improved by chemical means or not along with the development of science and technology and the requirement of people on better life quality can ensure that wood has natural aesthetic feeling, simultaneously has the capacity of degrading organic pollutants and achieves the self-cleaning function, and is a subject worthy of research. TiO 2₂Is a cheap, nontoxic, stable and efficient photocatalyst, and TiO is prepared under the illumination condition that the band gap energy is larger than that of the photocatalyst₂Can remove harmful organic matters and toxic gases and degrade organic dyes, thereby improving the environment to a great extent. But pure TiO₂Has low catalytic activity, and can improve TiO by doping metal ions or other oxidants₂The forbidden band width of the photocatalyst prevents the recombination of photoproduction electrons and holes, and improves the photocatalytic efficiency of the photocatalyst.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

Aiming at the defects that the efficiency effect of a composite film formed on the surface of wood by a sol-gel method in the prior art is not obvious in the aspect of improving the surface photocatalysis of the wood and the preparation process is complicated, the invention provides a method for preparing Fe on the surface of wood³⁺Doped TiO 2₂/SiO₂The method of composite film aims at obtaining Fe capable of raising the surface photocatalytic performance of timber and degrading pollutant to reach self-cleaning effect³⁺Doped TiO 2₂/SiO₂A method of composite membrane.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

preparation of Fe on wood surface³⁺Doped TiO 2₂/SiO₂A method for the lamination of a membrane, comprising the following operative steps:

(1) preparing titanium sol: taking tetrabutyl titanate, adding ethanol a for mixing, and then adding acetylacetone to prepare a solution A; mixing ethanol B, water and nitric acid to prepare a solution B; slowly pouring the solution B into the solution A under the condition of heating and stirring, and continuously stirring for 20min to prepare a titanium solution;

(2) preparing silica sol: mixing ethyl orthosilicate, ethanol, water and acetylacetone to obtain a mixed solution, dropwise adding nitric acid to adjust the pH of the solution to 2-3, and heating and stirring to obtain silica sol;

(3)Fe³⁺doping: uniformly mixing the titanium sol prepared in the step (1) and the silica sol prepared in the step (2), and adding Ti⁴ ⁺Based on Fe³⁺：Ti⁴⁺Adding ferric nitrate according to the proportion of 1: 10-40, heating and stirring for 30min to obtain fully mixed Fe³⁺Doping sol;

(4) wood impregnation: putting wood into the Fe prepared in the step (3)³⁺Dipping in doped sol, and then vertically pulling at the speed of 1.5mm/s, namely removing Fe from wood³⁺Doping sol; and repeating dipping and lifting for 2-3 times, and drying to obtain the product.

Preferably, the molar ratio of tetrabutyl titanate, (ethanol a + ethanol b), water, nitric acid and acetylacetone in the step (1) is 1:10:2:0.2: 0.05; the ethanol a is twice of the ethanol b, and the ethanol a and the ethanol b are both absolute ethanol.

Preferably, the molar ratio of the ethyl orthosilicate, the ethanol, the water and the acetylacetone in the step (2) is 1:6:8: 0.05.

Preferably, the drying in step (4) is carried out at 80 ℃ for 12 hours.

Preferably, the wood in step (4) is eucalyptus.

Preferably, the ferric nitrate used in step (3) is ferric nitrate nonahydrate.

Compared with the prior art, the invention has the following beneficial effects:

the invention utilizes sol-gel technology to prepare surface-loaded Fe³⁺Doped TiO 2₂/SiO₂The eucalyptus wood of the composite film limits the silicon-titanium ratio and the iron ion doping amount, and the wood impregnation mode improves the surface photocatalytic performance of the eucalyptus wood, so that the eucalyptus wood can degrade dirtThe dye achieves the self-cleaning effect, expands the application field of the artificial board and improves the added value of the product, and has great significance for continuously promoting the cultivation of the artificial forest eucalyptus.

Drawings

FIG. 1 shows different Ti's in examples according to the invention⁴⁺/Fe³⁺And Ti⁴⁺/Si⁴⁺XRD spectrum of the mole ratio sample.

FIG. 2 is a scanning electron micrograph of a product prepared according to example 1 of the present invention.

FIG. 3 is a scanning electron micrograph of a product prepared according to example 2 of the present invention.

FIG. 4 is a scanning electron micrograph of a product prepared according to comparative example 1 of the present invention.

FIG. 5 is a scanning electron microscope image of the bonding surface of the product prepared by the preparation method of the invention.

FIG. 6 is an energy spectrum of a surface composite film prepared in example 2.

FIG. 7 shows different Ti's in examples according to the invention⁴⁺/Fe³⁺And Ti⁴⁺/Si⁴⁺FTIR spectra of molar ratio samples.

Detailed Description

The following detailed description is to be read in connection with the accompanying drawings, but it is to be understood that the scope of the invention is not limited to the specific embodiments. The wood used in the examples was Eucalyptus (Eucalyptus robusta) collected from a Guangxi south China orchard and sawn to a size of 35mm by 25mm by 5 mm. Before use, the mixture is treated by ultrasonic treatment for 20min with clear water, dried for 6h at 80 ℃ and then placed in a drying dish for later use.

Reagents used in the examples: butyl titanate (mass fraction is more than or equal to 99.0 percent), absolute ethyl alcohol (mass fraction is more than or equal to 99.7 percent) and Tianjin Damao chemical reagent factory; ethyl orthosilicate and acetylacetone (mass fraction is more than or equal to 99.0 percent), and the product is prepared in a chemical reagent factory of Polygala department; nitric acid with the mass fraction of 65.0-68.0 percent, Chengdu Jinshan chemical reagent company Limited; ferric nitrate nonahydrate, the mass fraction is more than or equal to 98.5 percent, Nanjing chemical reagent GmbH; deionized water.

The test instrument: nicolet iS 50 fourier transform infrared spectrometer (FT-IR), american siemer feishel; S-3400N Scanning Electron Microscope (SEM), Hitachi, Japan; DX-2700A polycrystal X-ray diffractometer (XRD), Dandong Haoyuan instruments, Inc.; model SP-75 visible spectrophotometer, shanghai spectrometer limited; magnetic stirrer, drying oven, Yongguang medical instruments, Inc., Beijing.

Example 1

Preparation of Fe on wood surface³⁺Doped TiO 2₂/SiO₂The method for compounding the membrane comprises the following operation steps:

(1) preparing titanium sol: tetrabutyl titanate according to the molar ratio: anhydrous ethanol: deionized water: nitric acid: respectively weighing tetrabutyl titanate, absolute ethyl alcohol, deionized water, nitric acid and acetylacetone in a weight ratio of 1:10:2:0.2:0.05, wherein ethanol a accounts for 2/3 of the absolute ethyl alcohol obtained by weighing, ethanol b accounts for 1/3 of the absolute ethyl alcohol obtained by weighing, adding ethanol a into tetrabutyl titanate, mixing, and then adding acetylacetone to prepare solution A; mixing ethanol B, deionized water and nitric acid to prepare a solution B; slowly pouring the solution B into the solution A under the condition of heating and magnetic stirring, and continuously stirring for 20min to prepare a titanium solution;

(2) preparing silica sol: according to the mol ratio, ethyl orthosilicate: anhydrous ethanol: deionized water: respectively weighing ethyl orthosilicate, absolute ethyl alcohol, deionized water and acetylacetone in a ratio of 1:6:8:0.05, mixing the ethyl orthosilicate, the absolute ethyl alcohol, the deionized water and the acetylacetone to obtain a mixed solution, dropwise adding nitric acid to adjust the pH of the solution to 2-3, and heating and magnetically stirring the solution for 20min to obtain silica sol;

(3)Fe³⁺doping: uniformly mixing the titanium sol prepared in the step (1) and the silica sol prepared in the step (2), and adding Ti⁴ ⁺Based on Fe³⁺：Ti⁴⁺Adding ferric nitrate nonahydrate at a ratio of 1:20, heating and magnetically stirring for 30min to obtain well-mixed Fe³⁺Doping sol;

(4) wood impregnation: putting the eucalyptus wood into the Fe prepared in the step (3)³⁺Soaking in doped sol to obtain woodWetting the surface of the wood, vertically pulling at a speed of 1.5mm/s to separate the wood from Fe³⁺Mixing with sol, repeating the above steps for 3 times, and drying at 80 deg.C for 12 hr to obtain Fe³⁺Doped TiO 2₂/SiO₂A composite membrane.

Example 2

(3)Fe³⁺doping: uniformly mixing the titanium sol prepared in the step (1) and the silica sol prepared in the step (2), and adding Ti⁴ ⁺Based on Fe³⁺：Ti⁴⁺Adding ferric nitrate nonahydrate at a ratio of 1:40, heating and magnetically stirring for 30min to obtain well-mixed Fe³⁺Doping sol;

(4) wood impregnation: putting the eucalyptus wood into the Fe prepared in the step (3)³⁺Soaking in doped sol until the surface of wood is wet, vertically pulling at a speed of 1.5mm/s to separate wood from Fe³⁺Doping the solThen repeating the above steps of dipping and pulling for 2 times, and drying at 80 ℃ for 12 hours to obtain Fe³⁺Doped TiO 2₂/SiO₂A composite membrane.

Example 3

(3)Fe³⁺doping: uniformly mixing the titanium sol prepared in the step (1) and the silica sol prepared in the step (2), and adding Ti⁴ ⁺Based on Fe³⁺：Ti⁴⁺Adding ferric nitrate nonahydrate at a ratio of 1:10, heating and magnetically stirring for 30min to obtain well-mixed Fe³⁺Doping sol;

(4) wood impregnation: putting the eucalyptus wood into the Fe prepared in the step (3)³⁺Soaking in doped sol, vertically pulling at 1.5mm/s to separate wood from Fe³⁺Mixing with sol, repeating the above steps for 3 times, and drying at 80 deg.C for 12 hr to obtain Fe³⁺Doped TiO 2₂/SiO₂A composite membrane.

Comparative example 1

(4) wood impregnation: putting the eucalyptus wood into the Fe prepared in the step (3)³⁺Soaking the doped sol for 1 hour, taking out, aging at room temperature for 6 hours, repeating the soaking and aging steps for 1 time, and drying at 80 ℃ for 12 hours to obtain Fe³⁺Doped TiO 2₂/SiO₂A composite membrane.

Comparative example 2

(4) Wood impregnation: putting eucalyptus into the step(3) Preparation of the resulting Fe³⁺Soaking the doped sol for 20 minutes, taking out, then aging for 20 minutes at room temperature, then repeating the soaking and aging of the procedures for 2 times, and drying for 12 hours at 80 ℃ to obtain the nano-silver doped silica sol.

The rest of the operation was exactly the same as in comparative example 1.

Comparative example 3

(3)Fe³⁺doping: uniformly mixing the titanium sol prepared in the step (1) and the silica sol prepared in the step (2), and adding Ti⁴ ⁺Based on Fe³⁺：Ti⁴⁺Adding ferric nitrate nonahydrate at a ratio of 1:4, heating and magnetically stirring for 30min to obtain well-mixed Fe³⁺Doping sol;

(4) wood impregnation: putting the eucalyptus wood into the Fe prepared in the step (3)³⁺Soaking in doped sol until the surface of wood is wet, vertically pulling at a speed of 1.5mm/s to obtain woodRemoval of Fe³⁺Mixing with sol, repeating the above steps for 3 times, and drying at 80 deg.C for 12 hr to obtain Fe³⁺Doped TiO 2₂/SiO₂A composite membrane.

And (3) detection:

(1) the eucalyptus wood obtained in example 1 and example 2 was subjected to X-ray diffraction to obtain a spectrum shown in FIG. 1, which shows that Ti is present in⁴⁺/Fe³⁺In the sample (20STF-3) having the molar ratio of 20, the diffraction angle of the anatase (101) plane was slightly larger than that of Ti⁴⁺/Fe³⁺Sample (40STF-3) at a molar ratio of 40, which is probably due to Fe³⁺Into the TiO₂Formation of Fe in the crystal lattice³⁺—O—Ti⁴⁺Has a lattice tension greater than Ti⁴⁺— O—Ti⁴⁺Resulting in lattice expansion.

(2) The formation of the composite films of the products prepared in example 1, example 2 and comparative example 1 is observed in a scanning electron microscope, the scanning electron microscope images of the products are respectively shown in fig. 2, fig. 3 and fig. 4, and it can be seen that the continuity of the composite film prepared by the method of the present invention is superior to that of the composite film prepared by the dipping method as a whole, and the surface flatness of the composite film prepared by the present invention is high. When the film is formed by the method of the present invention, the more the number of repetition times is, the better the continuity of the film formation is (shown in FIG. 5). When the combined surface of the wood and the film prepared in comparative example 1 is observed under a scanning electron microscope, the surface of the wood is covered with 1 layer of film, but some blank positions still exist, which indicates that the complete and continuous film layer is not formed on the surface of the wood, the thickness of the observed film layer is about 30 μm, and the composite film is formed only on the surface of the wood and does not penetrate into the interior of the wood.

(3) The energy spectra of the products obtained in examples 1 and 2 and comparative example 1 were obtained by a DX-2700A polycrystal X-ray diffractometer, as shown in FIG. 6, it can be seen from FIG. 6 that the composite film contains a trace amount of Fe element in addition to Si and Ti element, which confirms the analysis results of the XRD and FT-IR spectra, Fe³⁺Doping TiO with ionic valence state₂In the crystal lattice of (1).

(4) Different Fe³⁺Photocatalytic activity of the doped composite film:

examples 1-3, comparative example 3 Fe³⁺Doped TiO 2₂/SiO₂Irradiating the composite film with an ultraviolet lamp under the irradiation condition of 30W for 2h, and detecting different Fe³⁺The degradation rate of the composite film prepared by doping amount to methyl orange is shown in table 1:

table 1: photocatalytic degradation rate

	Fe³⁺Amount of doping	Rate of degradation
			Example 1	1:20	40.37％
Example 2	1:40	35.89％
			Example 3	1:10	39.99％
Comparative example 3	1:4	19.55％

As can be seen from Table 1, due to Fe³⁺/Fe⁴⁺The energy level of the TiO is higher than that of anatase type TiO₂Valence band edge of, and Fe³⁺/Fe²⁺Although the energy level of the titanium dioxide is lower than that of rutile phase TiO₂The valence band edge of (1), but the band gap energy of the anatase phase itself is larger than that of the rutile phase, and Fe is likely to be affected²⁺/Fe³⁺Energy level of with TiO₂The relative position between the conduction bands makes it a capture agent for photo-generated electrons. Further, Fe³⁺Phase contrast with Ti⁴⁺Has higher oxidation-reduction potential energy, is easy to accept electrons to be reduced, even compared with Ti⁴⁺And is more likely to become a capture site for photo-generated electrons, thereby facilitating efficient separation of charges. Thus, doping with Fe³⁺The probability of photo-generated electron-hole recombination can be reduced, thereby being beneficial to improving the photocatalytic activity.

Fe³⁺After photo-generated electrons and photo-generated holes are captured, the photo-generated electrons and the photo-generated holes are respectively changed into Fe²⁺And Fe⁴⁺，Fe²⁺Is in unstable transition state and is easy to be converted into TiO₂Surface or adjacent surface Ti⁴⁺Adsorbed O₂Releasing trapped electrons for oxidation to Fe³⁺Shallow trapping is formed, which causes the photo-generated electrons-holes to move rapidly and be effectively separated; at the same time, O₂Reduction to O^2-And further degrading methyl orange. Fe⁴⁺The trapped electrons are reduced to Fe³⁺To make OH on the surface^-Becomes OH radical. Thus, proper amount of Fe is doped³⁺The probability of photo-generated electron-hole recombination can be reduced, thereby being beneficial to improving the photocatalytic activity.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. On the surface of woodPreparation of Fe³⁺Doped TiO 2₂/SiO₂Method for the lamination of membranes, characterized in that it comprises the following operative steps:

(1) preparing titanium sol: taking tetrabutyl titanate, adding ethanol a for mixing, and then adding acetylacetone to prepare a solution A; mixing ethanol B, water and nitric acid to prepare a solution B; slowly pouring the solution B into the solution A under the condition of heating and stirring, and continuously stirring for 20min to prepare a titanium solution; the molar ratio of the tetrabutyl titanate, (ethanol a + ethanol b), water, nitric acid and acetylacetone is 1:10:2:0.2: 0.05; the ethanol a is twice of the ethanol b;

(2) preparing silica sol: mixing ethyl orthosilicate, ethanol, water and acetylacetone to obtain a mixed solution, dropwise adding nitric acid to adjust the pH of the solution to 2-3, and heating and stirring to obtain silica sol; the molar ratio of the ethyl orthosilicate to the ethanol to the water to the acetylacetone is 1:6:8: 0.05;

(3)Fe³⁺doping: uniformly mixing the titanium sol prepared in the step (1) and the silica sol prepared in the step (2), and adding Ti⁴⁺Based on Fe³⁺：Ti⁴⁺1:10 or 1:20, adding ferric nitrate, heating and stirring for 30min to obtain fully mixed Fe³⁺Doping sol;

2. The method of claim 1, wherein: the drying in the step (4) is drying for 12 hours at 80 ℃.

3. The method of claim 1, wherein: the wood in the step (4) is eucalyptus.

4. The method of claim 1, wherein: the ferric nitrate adopted in the step (3) is ferric nitrate nonahydrate.