Please select the most similar patent number from A, B, C and D. Which number is?
A method of preparing a nano-scale zero-valent iron, comprising the following steps: (1) adding, in an inert atmosphere, polyethylene glycol and deoxy ethanol to an aqueous solution of ferrous salt, and mixing; (2) mixing the solution obtained in step (1) with an alkaline aqueous solution containing boron hydride and performing a reduction reaction; (3) after the reduction reaction in (2) is complete, obtaining a precipitate; and (4) vacuum drying the precipitate to obtain nano-scale zero-valent iron. A surfactant combined with the prepared nano-scale zero-valent iron can markedly improve remediation efficiency of soil polluted with volatile organic compounds (VOCs).
A: A method for preparing sodium-based bentonite loaded zero-valent iron. First, natural bentonite is fully sodiumized at a pH value of 3, and then sodium-based bentonite and an iron salt are evenly mixed according to a specific ratio and placed in a three-necked flask; the pH value is adjusted to 11 by using a sodium hydroxide lye, an excessive amount of sodium borohydride solution is added dropwise to the three-necked flask, stirring is continued, and nitrogen is continuously aerated during the reaction so as to ensure that the inside of the flask is in an oxygen-free state; after finishing dropwise adding the sodium borohydride, stirring is continued such that same is fully reacted with the iron salt, and the product is loaded on the bentonite; and centrifugal separation is performed and the supernatant is removed, the remaining solid is washed three times by using pure water and absolute ethanol, and then freeze-drying is carried out to obtain zero-valent iron sodium-based bentonite. Further disclosed is an application of sodium-based bentonite loaded zero-valent iron. The rates of removing lead and pentachlorophenol from compound polluted groundwater by a sodium-based bentonite loaded zero-valent iron material can reach 98.0% and 96.1%, providing a realistic and feasible method for solving the problem of compound pollution of groundwater.
B: A supercritical hydrothermal synthesis method for metal or metal oxide nanoparticles comprises the following steps: fully mixing a soluble metal salt solution with an alkaline solution or with a mixture of an alkaline solution, a reducing agent solution and an organic ligand to serve as a reaction precursor of supercritical hydrothermal synthesis; using a high-pressure pump to separately pressurize and pump the reaction precursor and preheated supercritical water into a mixer, heating up by direct mixing, and then performing a supercritical hydrothermal synthesis reaction; and after reaction for a period of time, cooling, centrifuging and drying the obtained product, so as to obtain metal or metal oxide nanoparticles. The metal or metal oxide nanoparticles prepared by using the method have the advantages of small particle size, good dispersibility, and high purity.
C: The present invention relates to a method for preparing a water-purifying charcoal composite material with a low loading amount of nano zero-valent iron and nano silver. The water-purifying charcoal composite material with a low loading amount of nano zero-valent iron and nano silver prepared by the preparation method has a high specific surface area, the loading amounts of iron and silver are low in the composite material, and the particle sizes of the nano zero-valent iron and nano silver particles are both less than 20 nm. The water-purifying charcoal composite material can simultaneously adsorb and convert or degrade a variety of pollutants in drinking water, and the release amount of iron and silver is extremely low, and so same is a water-purifying material with great application value.
D: The present invention provides a method for preparing a graphene/nano-carbon particle composite. The method comprises: 1) oxidizing graphite to prepare oxidized graphene, and adding the obtained oxidized graphene into water to prepare a suspension liquid; 2) adding nano-carbon particles into a water solution with a surface active agent to obtain a suspension liquid of the nano-carbon particles; 3) mixing the suspension liquid of the oxidized graphene with the suspension liquid of the nano-carbon particles, so as to obtain a mixed suspension liquid; 4) performing spray drying on the uniformly mixed suspension liquid to obtain powder; and 5) performing reduction treatment on the powder obtained in step 4), or placing the powder obtained in step 4) in an inert gas atmosphere, preheating the powder, and then performing reduction reaction in a reducing atmosphere, so as to finally prepare the graphene composite loaded with the nano-carbon particles. The present invention also relates to the graphene/nano-carbon particle composite obtained by using the method of the present invention, and applications of the graphene/nano-carbon particle composite used as a supercapacitor material, a catalyst carrier or an infrared optical material.
Answer: B