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CN-121974362-A - Method for preparing hectorite nano-powder by in-situ stripping of laponite reaction solution

CN121974362ACN 121974362 ACN121974362 ACN 121974362ACN-121974362-A

Abstract

The invention discloses a method for preparing hectorite nano powder by in-situ stripping of a laponite reaction solution, and belongs to the technical field of nano powder preparation. The method aims to solve the problems of complex technological process, low stripping efficiency, poor product uniformity and difficult continuous production in the prior art for preparing the hectorite nanosheets. The preparation method comprises the following steps of naturally cooling reaction liquid and ageing for 24 hours at room temperature after a hectorite hydrothermal synthesis reaction is finished, diluting with water until the mass concentration of the hectorite is 1-10 wt%, directly carrying out high-pressure homogenization treatment on the diluted liquid under the pressure of 10-100 MPa without drying, realizing interlayer in-situ efficient stripping by utilizing the shearing, impact and cavitation effects, carrying out filter pressing washing on the homogenized liquid until the conductivity of discharged liquid is lower than 5 mu S/cm, and finally carrying out strong drying under the conditions of 90-130 ℃ and the grading frequency of 5-25 Hz to obtain the stripped hectorite nano powder with the water content of less than or equal to 2.0%. The invention omits the traditional drying redispersion step by the integrated strategy of synthesis, in-situ stripping and continuous treatment, and has the advantages of obviously simplified process flow, reduced energy consumption and obvious stripping effect.

Inventors

  • LU YUSHEN
  • WANG AIQIN
  • MOU BIN
  • ZHANG TIANZHI
  • XU JIANG
  • ZHANG TIANYI
  • YANG FANGFANG
  • HUI AIPING

Assignees

  • 中国科学院兰州化学物理研究所
  • 江苏海明斯新材料科技有限公司

Dates

Publication Date
20260505
Application Date
20260211

Claims (5)

  1. 1. The method for preparing the hectorite nano powder by in-situ stripping of the laponite reaction liquid is characterized by comprising the following steps of: (1) After the hectorite liquid-phase hydrothermal synthesis reaction is completed, naturally cooling the obtained reaction system to room temperature, and standing and ageing at room temperature for at least 24 hours; (2) Diluting the aged reaction solution in the step (1) with water to adjust the mass concentration of hectorite solids in the reaction solution to be 1 wt-10 wt%; (3) Directly carrying out high-pressure homogenization treatment on the diluent obtained in the step (2), wherein the working pressure of the high-pressure homogenization treatment is 10-100 MPa, and obtaining stripping homogenized liquid; (4) Carrying out filter pressing and washing on the stripping homogenized liquid until the conductivity of the last washing effluent is less than 5 mu S/cm; (5) And (3) performing strong drying on the filter cake washed in the step (4), wherein the strong drying condition is that the drying temperature is 90-130 ℃, the grading frequency is 5-25 Hz, and the flaking hectorite nano powder with the water content not more than 2.0% is obtained.
  2. 2. The method according to claim 1, wherein in step (3), the high-pressure homogenizing treatment is repeated 2 times or cyclically.
  3. 3. The method according to claim 1, wherein in the step (4), the pressure filtration is performed by using a high-pressure membrane filter press, and the feeding pressure is 1.5 MPa to 2.8 MPa.
  4. 4. The method according to claim 1, wherein in step (4), the water content of the filter cake obtained after the press filtration is less than 50%.
  5. 5. The method of any one of claims 1-4, wherein the thickness of the exfoliated hectorite nano-powder obtained by the method is 1 nm-6 nm.

Description

Method for preparing hectorite nano-powder by in-situ stripping of laponite reaction solution Technical Field The invention belongs to the technical field of nano powder preparation, and particularly relates to a method for preparing hectorite nano powder by in-situ stripping of laponite reaction liquid. Background Laponite (Laponite) is a typical synthetic phyllosilicate material having a regular two-dimensional lamellar structure with a chemical formula of Na 0.7Si8Mg5.5Li0.3O20(OH)4. In industrial preparation, water glass, alkali, magnesium salt, lithium salt, other metal salts and the like are generally used as raw materials, and a precursor is converted into a hectorite crystal with good crystallization through hydrothermal crystallization reaction under high temperature and high pressure conditions. Hectorite is widely used in the fields of catalysis, adsorption, energy storage, composite materials and the like due to its high specific surface area, excellent ion exchange capacity and unique rheological properties. However, due to strong interlayer electrostatic attraction and van der Waals forces, the synthesized hectorite nanoplatelets tend to be tightly stacked to form micron-sized aggregates, resulting in difficulty in fully exploiting their high specific surface area and intrinsic properties. Thus, how to achieve efficient, uniform exfoliation of single-or few-layered laponite nanoplatelets remains an important challenge in current research. At present, various technical routes have been developed for the exfoliation of layered silicate minerals, but the existing methods have been mainly developed around natural layered silicate minerals such as montmorillonite, kaolin, and the like. The related patent technology covers strategies such as hydration swelling (CN 202321278338.4, CN 202310904374.5), ultrasonic stripping (CN 201910090329.4, CN 202210563180.9), mechanical grinding stripping (CN 200510047794.8, CN 201911246080.8) and the like. However, these methods generally involve post-treatment processes such as ion exchange and organic intercalation, and have common problems such as complicated flow, long treatment period, high energy consumption, and uneven stripping effect. For laponite, the structure is regular, the interlayer acting force is strong, and the efficient and uniform stripping is difficult to realize by adopting the traditional post-treatment strategy aiming at natural minerals. At present, no research has been reported on the realization of one-step in-situ stripping by utilizing a hectorite synthesis reaction system. Therefore, developing an in-situ stripping technology which can directly induce the separation of nano-sheets in the preparation process of hectorite has important significance for fully exerting the excellent performance under the nano-scale. Disclosure of Invention Aiming at the technical problems of complex flow, high energy consumption, low stripping efficiency, poor product uniformity, incapability of realizing continuous production and the like in the preparation process of the laponite nanosheets in the prior art, the invention aims to provide a method for stripping laponite reaction liquid in situ. The method aims to overcome the defects of the traditional path of 'drying before synthesis and stripping after treatment', and directly realizes the efficient and uniform stripping of the hectorite in the synthesis reaction liquid, thereby simplifying the process, reducing the energy consumption, and being suitable for large-scale continuous production so as to obtain the few-layer hectorite nano-sheet with complete structure and uniform thickness. In order to achieve the above purpose, the invention adopts the following technical scheme: the method for preparing the hectorite nano powder by in-situ stripping of the laponite reaction liquid comprises the following steps: (1) After the hectorite liquid-phase hydrothermal synthesis reaction is completed, naturally cooling the obtained reaction system to room temperature, and standing and ageing at room temperature for at least 24 hours; (2) Diluting the aged reaction solution in the step (1) with water to adjust the mass concentration of hectorite solids in the reaction solution to be 1 wt-10 wt%; (3) Directly carrying out high-pressure homogenization treatment on the diluent obtained in the step (2), wherein the working pressure of the high-pressure homogenization treatment is 10-100 MPa, and obtaining stripping homogenized liquid; (4) Carrying out filter pressing and washing on the stripping homogenized liquid until the conductivity of the last washing effluent is less than 5 mu S/cm; (5) And (3) performing strong drying on the filter cake washed in the step (4), wherein the strong drying condition is that the drying temperature is 90-130 ℃, the grading frequency is 5-25 Hz, and the flaking hectorite nano powder with the water content not more than 2.0% is obtained. In the above preparation steps, the high-pressur