Method for large-scale continuous preparation of nanometer zero-valent metal materials

Abstract

The invention relates to preparation of nanometer materials and specifically discloses a method for large-scale continuous preparation of nanometer zero-valent metal materials. The method includes thefollowing steps that (1) biomass adsorption particles and a metal salt ion solution make contact in a soaking mode according to the solid-to-liquid ratio of 1:1-50 g / ml, and after filtering, separation and washing, water is added for size mixing to form a suspension state according to the solid-to-liquid ratio of 1:1-50 g / ml, and a material A is obtained; (2) a sodium borohydride aqueous solutionwith the concentration being 0.1-1 mol / L is prepared to serve as a material B; and (3) the material A and the material B are added into an auger type spiral mixer in a mixed mode according to the volume-flow rate ratio of 1:1-5, mixing and reinforcing contact are carried out in the auger type spiral mixer, a reduction reaction is completed, residual reagents are removed by rapidly washing outputmaterials, and the nanometer zero-valent metal loaded composite materials are obtained. By means of the method, the technical problems that nanometer zero-valent metal is prone to air oxidation and solid-liquid separation and washing are difficult in large-scale preparation are solved, and a highly engineered technological approach for large-scale preparation of the nanometer zero-valent metal materials is provided.

Description

technical field [0001] The invention relates to the preparation of nanometer materials, in particular to a method for large-scale continuous preparation of nanometer zero-valent metal materials. Background technique [0002] Nano zero-valent iron, nano-zero-valent nickel, nano-zero-valent copper, nano-zero-valent silver, nano-zero-valent iron-nickel, nano-zero-valent iron-copper, nano-zero-valent iron-nickel-copper, nano-zero-valent iron-silver, nano-zero-valent iron-nickel Nano-scale metal materials with single or multiple components such as silver and copper have received extensive attention in the fields of environmental purification and restoration, sterilization and disinfection, catalytic degradation, and hydrometallurgy. Taking nano-zero-valent iron as an example, since its appearance in 1997, it has been widely concerned in the treatment of heavy metal wastewater resources, the degradation and detoxification of residual organochlorine pesticides in water and soil, an...

AI Technical Summary

Problems solved by technology

This study provides a good prototype design for the large-scale preparation of nano-zero-valent iron, but there are also outstanding problems, such as the direct use of soluble iron salts, and its aqueous solution is often strongly acidic due to the hydrolysis of ferric iron. This has brought great trouble for the effective utilization of strong alkaline reducing agents such as sodium borohydride, and if the pH value of the iron ion solution is increased, as long as the pH is greater than 2, the ferric ion may be precipitated immediately. This is not conducive to being quickly, uniformly and fully reduced to nano-sized zero-valent iron

Such a reduction reaction, because the contact reaction time between the reagents is very short, the utilization efficiency of the reducing agent is not high, and the content and purity of the metallic iron component are not necessarily high, thus affecting the activity and use efficiency of the reduced iron powder

[0004] All in all, during the preparation and production process of traditional nano-zero-valent iron, several problems such as: agglomeration problem, rapid and uniform mixing reaction problem, difficult problem of solid-liquid separation and washing, easy oxidation by air, etc., are given to nano-zero-valent iron. The engineering scale-up preparation of iron and other nano-zero-valent metal powders has brought great challenges and restrictive technical bottlenecks

Although ordinary atomized iron powder or carbonyl iron powder can be used to replace part of nano-zero-valent iron to achieve the same effect, but because the particle size of these iron powders is mostly in the micron or even tens of micron levels, their reactivity is lower than that of nano-zero-valent iron. If the price of iron is several times lower, the amount of iron powder used will increase greatly, causing the cost of raw materials to rise, and may cause serious secondary iron pollution

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