A kind of silicon oxide-coated nano-zero-valent iron particle and its preparation method and application

Abstract

The invention discloses silicon oxide-coated nanometer zero-valent iron particles, a preparation method and application thereof. The particles use nanometer zero-valent iron as the core and silicon oxide as the coating layer, and add NaBH to the mixed solution of iron salt and inorganic silicate under an inert gas atmosphere. 4 or KBH 4 The reducing agent is prepared by one-step reaction. Its preparation is as follows: adding iron salt to inorganic silicate solution, stirring under inert gas atmosphere to obtain a mixed solution; adding reducing agent NaBH drop by drop 4 or KBH 4 solution, stirred under an inert gas atmosphere to react, and a precipitate was obtained, which was separated, washed, and vacuum-dried to obtain the product. The present invention prepares silicon oxide-coated nano-zero-valent iron through a one-step simple liquid-phase reduction method, the process is simple, the raw material is cheap and easy to obtain, non-toxic and harmless, and the obtained novel nano-zero-valent iron particles have good dispersibility and small average particle size And uniform, strong antioxidant capacity, suitable for the treatment of organic wastewater.

Description

technical field [0001] The invention belongs to the technical field of nanomaterial preparation, and in particular relates to a silicon oxide-coated nanometer zero-valent iron particle and a preparation method and application thereof. Background technique [0002] The reduction and removal of harmful pollutants in the environment by using nanometer zero-valent iron (nZVI) is a widely researched technology at home and abroad in recent years. Compared with ordinary zero-valent iron powder, nZVI, as an excellent electron donor, not only has a smaller particle diameter and a larger specific surface area, but also has the advantage of nanometer size to provide abundant reactive sites and accelerate the efficiency of pollutant treatment. At present, this technology has been applied in the removal process of nitrate nitrogen, high-priced heavy metal ions, organic halides, nitro compounds and other harmful substances in water bodies. However, in the actual process implementation pr...

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Problems solved by technology

After nZVI reacts with pollutants, it will generate many iron oxide precipitates and adhere to the surface, and the continuous reduction activity is difficult to guarantee.

(4) Low recycling efficiency

However, there are still problems such as uneven particle distribution, easy agglomeration, poor dispersion, and low reactivity in the liquid phase preparation of nZVI. Therefore, many improved liquid phase reduction methods have emerged, mainly by adding dispersants and carriers to avoid the above defects.

Among them, Ross used sodium alginate microcapsules for loading in "A Preparation Method for Nano-iron Particles Loaded by Sodium Alginate Microcapsules" (patent application number: 201310104440.7). Although this improved technology improves the oxidation resistance of nano-iron and stability, but its preparation process is cumbersome and time-consuming, and at the same time, the participation of macromolecular organic substances in the separation and purification process leads to certain environmental pollution problems; "(patent application number: 200910069677.X), the use of silicon micropowder loading improves the anti-agglomeration of nano-zero-valent iron particles, but in the preparation process, it is necessary to add strong hydrochloric acid to the system to pre-modify the base silicon micropowder Re-separation, the process requires both batch and multiple complex operations and the participation of strong acid to obtain the loaded nZVI, which greatly increases the preparation cost

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