CN-121974364-A - Integrated preparation method for rapid depolymerization and viscosity reduction of hectorite nano-sheet

Abstract

The invention relates to an integrated preparation method for rapid depolymerization and viscosity reduction of hectorite nanosheets, which comprises the following steps: firstly, preparing laponite into suspension, then adding a certain amount of organic solvent, carrying out high-pressure homogenization treatment, and then carrying out filter pressing and strong drying to obtain the peeled and sticky laponite nano powder. The invention not only effectively solves the problems of structural damage, low stripping efficiency and the like in the laponite nanocrystallization process, but also obtains the nano powder with high suspension and low viscosity characteristics. The invention has the advantages of simple process, convenient operation, low cost and the like, and lays a key foundation material for preparing the hectorite efficient functional material.

Inventors

• WANG AIQIN
• LU YUSHEN
• MOU BIN
• XU JIANG
• WANG QIN

Assignees

• 中国科学院兰州化学物理研究所

Dates

Publication Date

20260505

Application Date

20260211

Claims (5)

1. 1. An integrated preparation method for rapid depolymerization and viscosity reduction of hectorite nano-sheets is characterized by comprising the following steps: (1) Preparing laponite into suspension with mass concentration of 0.1 wt% -5 wt%; (2) Adding an organic solvent accounting for 10% -70% of the volume of the suspension into the suspension, wherein the organic solvent is at least one of methanol, ethanol, isopropanol, acetone, n-propanol and tert-butanol; (3) Carrying out high-pressure homogenization treatment on the system added with the organic solvent under the pressure of 10-100 MPa; (4) Carrying out filter pressing on the homogenized material; (5) Performing strong drying on a filter cake obtained by filter pressing at 90-130 ℃ and a grading frequency of 5-25 Hz to obtain flaking and viscosity-reducing hectorite nano-powder with a thickness of 2-10 nm; when the hectorite nano-powder prepared by the method is reconstituted into a water-based suspension with the mass concentration of 5 wt%, the viscosity of the water-based suspension is reduced by more than 50% compared with that of the original hectorite suspension with the same concentration, which is not treated by the method.
2. 2. The method of claim 1, wherein the high pressure homogenization treatment in step (3) is repeated or cycled.
3. 3. The method according to claim 1, wherein in the step (4), the pressure filtration is performed by using a high-pressure diaphragm pressure filtration method, the feeding pressure is 1.5 MPa to 2.8 MPa, and the pressure filtration time is 2 hours to 6 hours.
4. 4. The process according to claim 1, wherein the organic solvent used in step (2) is recycled.
5. 5. The exfoliated and reduced viscosity laponite nano powder prepared by the method of any one of claims 1 to 4, wherein the thickness of the lamellar layer is 2 nm to 10 nm, and the viscosity of the lamellar layer in the water-based suspension with the mass concentration of 5wt% is more than 50% lower than that of the original laponite suspension with the same concentration.

Description

Integrated preparation method for rapid depolymerization and viscosity reduction of hectorite nano-sheet Technical Field The invention belongs to the technical field of nano powder preparation, and particularly relates to an integrated preparation method for rapid depolymerization and viscosity reduction of hectorite nano-sheets. Background Hectorite (Laponite) is an artificially synthesized layered silicate nanomaterial with a chemical formula of Na 0.7Si8Mg5.5Li0.3O20(OH)4 and a highly ordered two-dimensional lamellar structure (single lamellar diameter about 25-30 nm, thickness about 1 nm). The hectorite has wide application prospect in the fields of catalysis, adsorption, drug delivery, energy storage, high polymer composite materials and the like due to the high specific surface area, rich surface negative charge, excellent ion exchange capacity and unique rheological behavior. However, during conventional synthesis and storage, laponite nanoplatelets tend to form tightly stacked aggregates by electrostatic attraction, hydrogen bonding and van der waals forces, severely limiting the acquisition of monolithic or few-layered dispersions, affecting the full exploitation of intrinsic properties. To achieve efficient depolymerization exfoliation of lithium soap stone platelets, researchers have developed a variety of strategies including ion exchange methods (ACS Nano, 2010, 4, 717-724), organic intercalation methods (Langmuir, 2006, 22, 6696-6700;Materials Today Communications, 2025, 48, 113548), ultrasound-assisted exfoliation (APPLIED CLAY SCIENCE, 2010, 49, 21-28), and ball-milling-assisted exfoliation (CLAY MINERALS, 2012, 47, 341-353), among others. However, these methods still face many challenges in practical applications. Ion exchange methods, while effective in attenuating interlayer electrostatic interactions, typically require multiple and complex process flows. The organic intercalation method expands the interlayer spacing by introducing organic molecules, thereby promoting exfoliation, but the residual intercalating agent is often difficult to completely remove, and the final functional properties of the material are affected. Physical stripping means such as ball milling and ultrasonic are generally long in time, low in efficiency, high in energy consumption, nonuniform in stripping, easy to fracture in a sheet layer and the like, and high-efficiency stripping and structural integrity are difficult to achieve. Meanwhile, the hectorite is extremely easy to form a highly stable colloid suspension system in an aqueous phase due to the unique nano lamellar structure and surface charge characteristics of the hectorite, and shows remarkable high viscosity and even gelation behavior. While this high viscosity property is advantageous in some rheology control applications, it severely limits its applicability in functional modification and industrial processing. Studies show that the gelation behavior of hectorite is doubly regulated by ionic strength and solid content. As the salt concentration increases or the solids content increases, the interparticle electrostatic repulsion weakens, rapidly forming a three-dimensional network structure, leading to a sharp rise in system viscosity and even instantaneous gelation (Journal of Colloid AND INTERFACE SCIENCE, 2005, 283, 397-405). In such high viscosity or gel systems, reactant diffusion is limited and mass transfer is difficult, resulting in low efficiency and poor repeatability of subsequent treatments such as chemical modification, composite assembly and the like. Although gel kinetics can be controlled by adding pyrophosphate to effectively neutralize charge, this may not only interfere with the active sites on the laponite surface, but also affect its performance on key performance indicators such as biocompatibility, electrochemical stability, or polymer interfacial compatibility. Therefore, a new method capable of synchronously realizing rapid depolymerization, efficient stripping and remarkable viscosity reduction of hectorite is needed. Disclosure of Invention Aiming at the problems that the existing laponite nanosheet stripping technology is complex in process, low in efficiency, easy to cause damage to a lamellar structure, and the product viscosity is too high after stripping or under high solid content, the subsequent processing and application are severely restricted, and the like, the invention aims to provide the integrated preparation method which is simple in process and high in efficiency. The method can synchronously realize the rapid depolymerization, the efficient stripping and the remarkable viscosity reduction of the hectorite nano-sheets, thereby obtaining the hectorite nano-powder with high dispersibility and low viscosity, and providing a key material foundation for the practical application of the hectorite nano-powder in the fields of high-end composite materials, catalysis, biological medicines and the like. In order to a