Preparation methods of rare earth layered hydroxide nanosheets and rare earth layered hydroxide nanosheet sol

Abstract

The invention relates to preparation methods of rare earth layered hydroxide nanosheets and rare earth layered hydroxide nanosheet sol. The preparation method of the nanosheets comprises the followingsteps: preparing a lanthanum nitrate solution with a corresponding concentration, dissolving ammonium sulfate particles into the lanthanum nitrate solution according to a proportion so as to form a mixed solution, adjusting the pH of the mixed solution to 6-10, and continuously stirring to obtain uniform suspension; carrying out a reaction to obtain a product, immediately carrying out centrifugalseparation on the product, and drying to obtain the rare earth layered hydroxide La2(OH)4SO4.nH2O nanosheets. The rare earth layered hydroxide nanosheet sol is prepared by putting the prepared nanosheets into a formamide solution, carrying out ultrasonic centrifugal treatment, and then taking the supernatant. According to the preparation method, the rare earth layered hydroxide La2(OH)4SO4.nH2O nanosheets can be prepared in one step by using an ice-bath method, so that the problem that in the prior art, the compounds cannot be prepared into single-layer nanosheets by using the conventional intercalation-stripping method can be solved; furthermore, the preparation methods are simple in process and convenient to operate, and can realize mass production; the corresponding nanosheet sol is good in stability and material-saving.

Description

Technical field: [0001] The invention belongs to the technical field of material science, and in particular relates to a preparation method of a rare earth layered hydroxide nanosheet and a sol thereof. Background technique: [0002] La 2 (OH) 4 SO 4 ·nH 2 O is a layered rare earth compound RE 2 (OH) 4 SO 4 ·nH 2 One of O. Belonging to anionic layered compounds, the main layer of hydroxide is composed of nine coordination polyhedra [LaO 9 ] are connected by co-planar and common sides, the interlayer SO 4 2- The tetrahedron plays a role of charge balance through the covalent bonding of the two apex oxygen atoms with the adjacent two main layer plates respectively. The compound does not have the traditional layered rare earth compounds (such as RE 2 (OH) 5 A·nH 2 O, A = Cl, NO 3 etc.), so it is impossible to prepare ultra-thin nanosheets by the pillar-stripping process route. Its remarkable advantage is its special chemical ratio: the La / S molar ratio of the co...

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Problems solved by technology

The existing problems are: 1) In terms of synthetic technical route, the precipitant used in the precipitation method, such as hexamethylenetetramine, has slow hydrolysis at room temperature, and easy generation of formaldehyde and its derivatives in the air at high temperature to reduce the precipitation reaction yield. and other shortcomings

Although the hydrothermal method overcomes the above-mentioned shortcomings of the precipitation method, and has the advantages of high product purity and low pollution, the reaction process requires a lot of energy under hydrothermal conditions, and the stability of the reaction process is poor.

2) In terms of the properties of the obtained target product: La prepared by hydrothermal method and normal temperature precipitation method 2 (OH) 4 SO 4 ·nH 2 O is finally crystallized into thicker nano- or micro-sheets due to the higher reaction temperature, especially the product obtained by the precipitation method has a large degree of agglomeration and poor dispersion.

And both of these methods are difficult to achieve large-scale preparation

In addition, the thickness of the laminates of nanosheets prepared by these two methods can reach 30-300nm, and because this compound cannot be prepared by intercalation-exfoliation, it is currently impossible to obtain ultra- Thin rare earth layered hydroxide La 2 (OH) 4 SO 4 ·nH 2 O nanosheets, so the rare-earth layered hydroxide La with good stability cannot be obtained 2 (OH) 4 SO 4 ·nH 2 O nanosheet sol

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