阅读说明：本技术 一种Bi2O3/蒙脱石复合光催化材料及其制备方法 (Bi2O3Montmorillonite composite photocatalytic material and preparation method thereof ) 是由 李芳菲 任宣羽 薛兵 夏茂盛 张佳浩 薛壮壮 于永强 谢乐贤 殷作真 于金生 于 2019-09-16 设计创作，主要内容包括：本发明涉及一种Bi_2O_3/蒙脱石复合光催化材料及其制备方法,该方法可显著提升光催化剂的活性与吸附性,属于矿物材料加工利用领域。本发明充分利用经过超声的蒙脱石的单片层优良性质,很大程度的提升了蒙脱石的吸附作用,并改变了其表面零点电位值。将超声处理的蒙脱石溶液通过水热过程负载氧化铋,将蒙脱石的吸附能力和Bi_2O_3的可见光催化性能有机的结合在一起。该方法原料成本低、工艺简单、环境友好、制品分散性好、氧化铋形貌可控、且所得Bi_2O_3/蒙脱石复合光催化剂易回收、可见光催化活性好、性能稳定。(The invention relates to a Bi 2 O 3 Montmorillonite composite photocatalytic material and a preparation method thereof, the method can obviously improve the activity and the adsorptivity of a photocatalyst, and belongs to the field of mineral material processing and utilization. The invention fully utilizes the excellent properties of the single layer of the montmorillonite subjected to the ultrasonic treatment, greatly improves the adsorption effect of the montmorillonite and changes the surface zero potential value of the montmorillonite. Loading bismuth oxide on the montmorillonite solution subjected to ultrasonic treatment through a hydrothermal process, and regulating the adsorption capacity and Bi of the montmorillonite 2 O 3 The visible light catalytic performance of the catalyst is organically combined together. The method has the advantages of low cost of raw materials, simple process, environmental protection, good product dispersibility, controllable bismuth oxide morphology and Bi obtained 2 O 3 The montmorillonite composite photocatalyst is easy to recycle, and has good visible light catalytic activity and stable performance.)

1. Bi₂O₃The montmorillonite composite photocatalytic material is characterized in that sodium montmorillonite with the purity of more than 90 wt% is selected as montmorillonite in the composite material, wet purification, repeated high-power ultrasonic treatment and dilution are carried out to obtain 4-40 g/L highly dispersed few-layer montmorillonite suspension, and the suspension and bismuth-containing inorganic salt aqueous solution are subjected to premixing and hydrothermal synthesis under the condition from weak acid to weak base to realize crystallization of bismuth oxide nanosheets and compounding of the bismuth oxide nanosheets and the few-layer montmorilloniteCombined and interweaved growth to obtain Bi₂O₃A visible light type Bi of 0.5 to 4 in mass ratio to montmorillonite₂O₃Montmorillonite composite photocatalytic material.

2. The Bi according to claim 1₂O₃The montmorillonite composite photocatalytic material is characterized in that the bismuth-containing inorganic salt is one or two of bismuth nitrate and bismuth subnitrate.

3. The Bi according to claim 1₂O₃The preparation method of the montmorillonite composite photocatalytic material is characterized by comprising the following steps of:

1) Mixing a sodium-based montmorillonite raw material with the purity of more than 90 wt% with water to prepare slurry with the concentration of 10-100 g/L, treating for 1-5 min under 600-1500W of ultrasonic power, centrifuging for 3-6 min under the condition of 10000-15000 Xg, discarding bottom sediment, and obtaining further purified montmorillonite slurry with the concentration of 8-80 g/L;

2) Diluting the montmorillonite slurry obtained in the step 1 by adding a certain amount of water, and carrying out ultrasonic treatment for 1-3 min under the power of 600-1500W to finally obtain a highly dispersed 4-40 g/L few-layer montmorillonite micro-sheet suspension;

3) Weighing a certain amount of bismuth-containing inorganic salt to prepare an aqueous solution, then adjusting the pH value of the solution to 6-7, and adding the small-layer montmorillonite micro-layer suspension obtained in the step 2 to enable Bi in the system to be in a Bi state₂O₃The mass ratio of the bismuth to the montmorillonite is 0.5-4, the pH value of the system is adjusted to 7-9 after the mixture is fully stirred, the slurry is transferred to a closed reaction kettle after being uniformly stirred, the temperature is kept at 150-200 ℃ for 4-24 hours, and then solid-liquid separation, washing and precipitation, drying and grinding are carried out to obtain Bi₂O₃Montmorillonite composite photocatalytic material.

Technical Field

The invention relates to a visible light responding Bi₂O₃Montmorillonite composite photocatalytic material and a preparation method thereof, the method can obviously improve the visible light catalytic activity and the adsorptivity of a photocatalyst, and belongs to the field of mineral material processing and utilization.

background

Bi₂O₃The crystal is an important p-type semiconductor material, has a narrow forbidden band width, can effectively utilize visible light to carry out photocatalytic degradation on organic pollutants, and is a novel visible light catalyst which is widely concerned in recent years. In the synthesis of bismuth oxide, the Chinese patent No. CN109485096A discloses a process for preparing tetragonal bismuth oxide by hydrothermal synthesis. Yanghiping, wanglie et al in chinese patent No. CN107857300A disclose a method for preparing beta-type bismuth oxide by normal pressure boiling reflux method. Huhanxiang in the research on bismuth oxide nano powder preparation by bismuth steam oxidation, a metal steam oxidation method is adopted, and Bi solid is evaporated and subjected to gas phase oxidation by adding an auxiliary agent, so that nano Bi is prepared₂O₃Powder, however, although Bi₂O₃The semiconductor nanocrystalline catalyst has high efficiency, but the method is restricted by conditions of low vapor pressure, difficult evaporation and the like, and the production cost is higher. The preparation methods are limited by cost, or are difficult to separate and recover from a liquid phase, and are difficult to recycle, so that the further application of the preparation methods is limited.

For this reason, many researchers have attempted to fix or support the nanocrystalline photocatalyst on different carriers to solve the problem of photocatalysisThe recovery problem of the agent, and the reported carriers mainly include: activated carbon, silica gel, zeolite, fibers, and the like. Montmorillonite is a 2:1 type phyllosilicate mineral, and has the advantages of abundant reserves, low price and excellent dispersibility in water phase. Due to the silicon-aluminum substitution effect in the crystal lattice, the structural unit layer of the montmorillonite has natural negative charges and can adsorb Na⁺、K⁺、Mg²⁺、Ca²⁺And the montmorillonite has a series of excellent performances such as ion exchange property, water absorption property, expansibility, adsorbability and the like, and is an ideal photocatalyst carrier.

Montmorillonite has a certain application in the aspect of preparing a carrier of a photocatalyst, and Liu Xin soldiers disclose a nano TiO in Chinese patent (CN 107413322A)₂A method for producing pillared montmorillonite and application thereof. In this process, the montmorillonite not only solves the recycling problem, but also contributes to the improvement of the activity of the photocatalyst.

Li Farfy, Hummin et al in Chinese patent (CN 107469801A) disclose an anatase and montmorillonite laminated composite material obtained by using acid-base environment to regulate and control montmorillonite microchip recombination process and a preparation method thereof, wherein the laminated material needs to fully disperse montmorillonite carriers under alkaline condition and then carry out acid recombination. The further peeled montmorillonite has certain optimization effect when being compounded with the photocatalyst, and is beneficial to improving the activity of the photocatalyst.

Although montmorillonite has been used for a certain application in the preparation of a carrier of a photocatalyst and bismuth oxide has also been used as a photocatalyst, the compounding of bismuth oxide and montmorillonite has not been done at present.

The invention provides a method for preparing flaky Bi by using a montmorillonite micro-lamellar with high-power ultrasonic dispersion and a bismuth oxide precursor₂O₃A process for preparing montmorillonite-type composite photocatalyst features that the bismuth oxide in the composite photocatalyst is prepared by hydrothermal reaction from weak acid to alkali, and the whole process is simple and cheap, and the Bi with high crystallinity and ideal photocatalytic activity can be obtained without calcining and without use of organic additive₂O₃the montmorillonite composite photocatalyst obviously reduces the production energy consumption and the wastewater treatment difficulty.

Disclosure of Invention

The invention provides a Bi with visible light response₂O₃Montmorillonite composite photocatalyst and a hydrothermal preparation method thereof. The method fully utilizes the excellent dispersibility of the montmorillonite under the ultrasonic condition, prepares the flaky Bi with high crystallinity and high activity by using montmorillonite micro-sheets with high dispersion and 1-5 layers and bismuth oxide precursors under the synthesis condition from weak acid to alkali₂O₃The bismuth oxide-montmorillonite composite photocatalytic material has the advantages that the bonding area of bismuth oxide and montmorillonite is remarkably increased, the response of the composite photocatalytic material to visible light is enhanced, and the forbidden bandwidth of the composite photocatalytic material is remarkably reduced. So that Bi₂O₃The montmorillonite composite material has excellent adsorption performance, photocatalytic activity and stability.

The purpose of the invention is realized by the following technical scheme:

1) And (5) stripping the montmorillonite. Dispersing sodium-based montmorillonite with the purity of more than 90 wt% in water, stirring, preparing a solution with the concentration of 10-100 g/L, stripping for 1-5 min under the ultrasonic power of 600-1500W, centrifuging for 3-6 min under the condition of 10000-15000 Xg, and removing precipitates to obtain further purified montmorillonite slurry with the concentration of 8-80 g/L. And (3) adding a certain amount of distilled water into a proper amount of purified montmorillonite slurry for dilution, and stripping for 1-3 min at the ultrasonic power of 600-1500W again to obtain a highly dispersed small-layer montmorillonite micro-sheet suspension of 4-40 g/L.

2) And (5) performing hydrothermal compounding. Weighing a certain amount of bismuth salt, adding water to prepare a solution, and stirring until the bismuth salt is completely dissolved. And dropwise adding an alkaline pH regulator to adjust the pH value of the solution to 6-7. Adding the small-layer montmorillonite micro-lamellar suspension obtained in the step 1 into a bismuth salt solution to ensure that Bi in the system₂O₃The mass ratio of the alkaline pH regulator to the montmorillonite carrier is 0.5-4, after full stirring, the alkaline pH regulator is added dropwise again, the pH value of the system is adjusted to 7-9, magnetic stirring is continued for 1-2 hours, the slurry is transferred to a closed reaction kettle, and heat preservation is carried out for 4-16 hours at the temperature of 150-200 ℃. Solidifying after the sample is cooledLiquid separation, washing and precipitating, drying the precipitate at 80-110 ℃, and grinding to obtain Bi₂O₃Montmorillonite composite photocatalytic material.

The bismuth salt is defined as: any one or two of bismuth nitrate and bismuth subnitrate oxide.

Has the advantages that: the invention fully utilizes the excellent properties of the single-layer montmorillonite subjected to high-power ultrasound, and the peeled montmorillonite is a nano-flake with a large aspect ratio, the diameter of the nano-flake is about 100-200 nm, and the single-layer thickness of the nano-flake is only 1 nm. The montmorillonite peeled into the two-dimensional nano-sheet has the advantages that the specific surface area is obviously increased, and adsorption sites are completely released, so that the adsorption effect of the montmorillonite is greatly improved, the surface charge and the zero potential value of the montmorillonite are changed, and the direct electrostatic combination of bismuth oxide and the montmorillonite is obviously promoted. The growth mode of bismuth oxide is controlled by the montmorillonite micro-lamella obtained by ultrasonic treatment and the bismuth oxide precursor under the unique hydrothermal synthesis condition from weak acid to alkali, so that the high-crystallinity high-activity flaky Bi is prepared₂O₃The bismuth oxide-montmorillonite composite photocatalytic material has the advantages that the bonding area of bismuth oxide and montmorillonite is obviously increased, the response of the composite photocatalytic material to visible light is enhanced, and the forbidden bandwidth of the composite photocatalytic material is obviously reduced, so that the adsorption capacity of the montmorillonite and Bi are combined₂O₃The visible light catalytic performance of the catalyst is organically combined together. Compared with pure bismuth oxide under the condition of equivalent quantity, the sample prepared by the method has better photocatalytic degradation effect and lower cost. The method has the advantages of low cost of raw materials, simple process, environmental protection, good product dispersibility, controllable bismuth oxide morphology and Bi obtained₂O₃The montmorillonite composite photocatalyst is easy to recycle, and has good visible light catalytic activity and stable performance.

Drawings

FIG. 1 shows pure bismuth oxide and Bi obtained in examples 1, 2, 3 and 4₂O₃The montmorillonite composite photocatalyst has a photocatalytic degradation spectrum on methyl orange.

Detailed Description

The following is described in further detail with reference to examples: