CN110713242B

CN110713242B - Zero-valent iron material Fe @ iron fluoride and preparation method thereof

Info

Publication number: CN110713242B
Application number: CN201910734584.8A
Authority: CN
Inventors: 彭星; 张亚丽
Original assignee: Institute of Geographic Sciences and Natural Resources of CAS
Current assignee: Institute of Geographic Sciences and Natural Resources of CAS
Priority date: 2019-08-09
Filing date: 2019-08-09
Publication date: 2020-12-01
Anticipated expiration: 2039-08-09
Also published as: CN110713242A

Abstract

The invention relates to a zero-valent iron material Fe @ iron fluoride and a preparation method thereof. The invention provides a zero-valent iron material Fe @ iron fluoride, wherein the surface layer of the zero-valent iron material is an iron fluoride layer, and the iron fluoride layer replaces iron oxide of a zero-valent iron shell layer. The preparation method comprises the following steps: and heating and reacting the hydrofluoric acid solution with zero-valent iron for a period of time, and performing post-treatment to obtain the zero-valent iron material Fe @ iron fluoride. The zero-valent iron material Fe @ iron fluoride provided by the invention has extremely high activity, can greatly promote the corrosion efficiency of zero-valent iron, improves the heavy metal removal efficiency and the utilization rate of the zero-valent iron, and is beneficial to saving the cost of the zero-valent iron technology.

Description

Zero-valent iron material Fe @ iron fluoride and preparation method thereof

Technical Field

The invention belongs to the field of pollutant remediation in water and preparation of environmental materials, and particularly relates to a novel zero-valent iron material Fe @ iron fluoride, a preparation method and application thereof in pollutant removal.

Background

The zero-valent iron is used as a green, environment-friendly, economic and efficient multifunctional environment-friendly material and has good research and application prospects. Through research and development for more than 20 years, zero-valent iron has a good effect in the aspects of treating heavy metals, organic matters, nitrogen, phosphorus, mixed pollutants and the like, but the large-area application of the zero-valent iron in actual environmental remediation still has a challenge, mainly because iron is easy to react with oxygen or water, an iron oxide shell layer is formed on the surface of the zero-valent iron, and the iron oxide shell layer plays a role in protecting the zero-valent iron from being further oxidized and simultaneously can prevent the zero-valent iron from being corroded, namely the capacities of the iron to give electrons and release divalent iron ions are influenced. In order to solve this problem, researchers of the zero-valent iron technology have proposed various modification technologies, such as synthesis of nano zero-valent iron by changing the particle size of zero-valent iron, preparation of bimetallic materials such as iron copper or iron nickel, pretreatment of hydrogen and hydrochloric acid, reinforcement of weak magnetic field and microwave and electric field, and reinforcement technology of adding inorganic ions. Although the above improved technology can effectively improve the pollutant removal capability of zero-valent iron, researchers find that a new iron oxide shell layer is formed on the surface of zero-valent iron as the reaction proceeds, so that the utilization efficiency of zero-valent iron is affected, and therefore how to further improve the utilization efficiency of zero-valent iron is an urgent problem to be solved for influencing the comprehensive popularization and application of the zero-valent iron technology.

Disclosure of Invention

The invention aims to provide a novel zero-valent iron material Fe @ iron fluoride and a preparation method thereof.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the zero-valent iron material Fe @ iron fluoride is provided, the surface layer of the zero-valent iron material is an iron fluoride layer, and the iron fluoride layer replaces the iron oxide of the zero-valent iron shell layer.

In the above scheme, the iron fluoride includes but is not limited to Fe₃F₈·2H₂O and Fe₂F₅·2H₂O。

The preparation method of the zero-valent iron material Fe @ iron fluoride is provided, wherein hydrofluoric acid solution and zero-valent iron are heated and reacted for a period of time, and the zero-valent iron material Fe @ iron fluoride is obtained through post-treatment.

According to the scheme, the post-treatment comprises the following steps: after solid-liquid separation, washing with deionized water and ethanol respectively, and finally drying in a vacuum drying oven. The solid-liquid separation process can adopt the technologies of magnetic separation, gravity separation, centrifugal separation and the like.

According to the scheme, the mixture is washed for 3 times by deionized water and ethanol respectively, and dried for 12-18h in a vacuum drying oven at 25 ℃.

According to the scheme, the hydrofluoric acid is sourced from hydrofluoric acid wastewater discharged by industries such as market or photovoltaics.

According to the scheme, the concentration of the hydrofluoric acid is 0.1-2M, and the dosage of the zero-valent iron is 80-400 g/L.

According to the scheme, the reaction temperature is 50-120 ℃, and the reaction time is 2-7 h.

According to the scheme, the zero-valent iron is micron-sized zero-valent iron.

Provides a method for removing heavy metal pollution by using the zero-valent iron material Fe @ iron fluoride.

According to the scheme, the addition amount of the zero-valent iron material Fe @ iron fluoride is 0.2-1 g/L.

According to the scheme, the heavy metal pollution comprises chromium and arsenic.

According to the scheme, the heavy metal pollution concentration is 1-10 mg/L.

According to the scheme, stirring is carried out in the removing process, and the rotating speed can be 200 r/min.

The invention has the beneficial effects that:

the invention takes zero-valent iron (such as factory scrap iron, commercial zero-valent iron powder and the like) as a raw material, adds hydrofluoric acid for heating and modification, destroys the original iron oxide shell layer of the zero-valent iron by utilizing the acidity of hydrofluoric acid, and further forms a new iron fluoride layer on the surface of the zero-valent iron, so that the hydrophilicity of the prepared Fe @ iron fluoride is greatly improved, the Fe @ iron fluoride has extremely high activity, the corrosion efficiency of the zero-valent iron is greatly promoted, the efficiency of removing heavy metal and the utilization rate of the zero-valent iron are improved, and the cost of the zero-valent iron technology is saved.

Drawings

FIG. 1 is an XRD results plot of the original zero-valent iron (B) and Fe @ iron fluoride (Fe @ iron fluoride) (A) (example 1) (. t.Fe)₃F₈·2H₂O(PDF 76-2285)◆Fe₂F₅·2H₂O(PDF 84-0880)▲Fe⁰)；

FIG. 2 shows the original zero-valent iron (A) and Fe @ iron fluoride (Fe @ FeF)_x) Graph of contact angle results of (B) (example 1);

FIG. 3 shows Fe @ iron fluoride (Fe @ FeF)_x) Effect of removing heavy metal chromium (example 1);

FIG. 4 shows Fe @ Fe fluoride (Fe @ FeF)_x) Removal of heavy metal arsenic (example 1).

Detailed Description

Example 1

Firstly, 50mL of 0.1M hydrofluoric acid solution is prepared and put into a 100mL polytetrafluoroethylene bottle, and 4g of zero-valent iron is added. Reacting for 3h at 50 ℃, washing for 3 times by using deionized water and ethanol respectively, and filtering and drying a sample for 18h at 25 ℃ in a vacuum drying oven to obtain Fe @ iron fluoride. XRD results for the original zero-valent iron (a) and Fe @ iron fluoride (B), fig. 1 illustrates: the ferric fluoride layer ferric fluoride/ferrous mineral shell replaces the ferric oxide layer of the zero-valent iron shell. The contact angle results of the original zero-valent iron (A) and Fe @ iron fluoride (B) are shown in FIG. 2, and FIG. 2 illustrates that the hydrophilicity of the zero-valent iron material Fe @ iron fluoride is greatly improved.

At the rotation speed of 200 r/min, the initial concentration of hexavalent chromium is 5mg/L, the initial concentration of pentavalent arsenic is 1mg/L, the dosage of Fe @ iron fluoride is 0.2g/L, after the reaction is carried out for 30min, the removal rate of chromium reaches 90%, the removal rate of arsenic reaches 90%, and the removal efficiency of original zero-valent iron chromium and arsenic is about 3% and 15%. The utilization rate of zero-valent iron of the modified zero-valent iron Fe @ iron fluoride material reaches 50%, and the utilization rate of original zero-valent iron is only 10% (the utilization rate of zero-valent iron is the proportion of the amount of zero-valent iron consumed in the reaction to the total zero-valent iron, and can be characterized and quantified through XRD). The results of chromium and arsenic removal are shown in fig. 3 and 4, respectively.

Example 2

Firstly, 50mL of 1M hydrofluoric acid solution is prepared and put into a 100mL polytetrafluoroethylene bottle, and 6g of zero-valent iron is added. Reacting for 2h at 75 ℃, then washing for 3 times by using deionized water and ethanol respectively, filtering a sample, and drying for 12h at 25 ℃ in a vacuum drying oven to obtain Fe @ iron fluoride;

the rotating speed is 200 r/min, the initial concentration of hexavalent chromium is 10mg/L, the initial concentration of pentavalent arsenic is 2mg/L, the adding amount of Fe @ iron fluoride is 0.2g/L, after the reaction is carried out for 30min, the removal rate of chromium reaches 91%, and the removal rate of arsenic reaches 90%.

Example 3

Firstly, 50mL of 2M hydrofluoric acid solution is prepared and put into a 100mL polytetrafluoroethylene bottle, and 10g of zero-valent iron is added. Reacting for 2h at 75 ℃, then washing for 3 times by using deionized water and ethanol respectively, and filtering and drying a sample for 18h at 25 ℃ in a vacuum drying oven;

the rotating speed is 200 r/min, the initial concentration of hexavalent chromium is 5mg/L, the initial concentration of pentavalent arsenic is 1mg/L, the adding amount of Fe @ iron fluoride is 0.2g/L, after the reaction is carried out for 30min, the removal rate of chromium reaches 98%, and the removal rate of arsenic reaches 93%.

Example 4

Firstly, 50mL of 2M hydrofluoric acid solution is prepared and put into a 100mL polytetrafluoroethylene bottle, and 16g of zero-valent iron is added. Reacting for 2h at 120 ℃, then washing for 3 times by using deionized water and ethanol respectively, and filtering and drying a sample for 18h at 25 ℃ in a vacuum drying oven;

the rotating speed is 200 r/min, the initial concentration of hexavalent chromium is 5mg/L, the initial concentration of pentavalent arsenic is 1mg/L, the adding amount of Fe @ iron fluoride is 0.2g/L, after the reaction is carried out for 30min, the removal rate of chromium reaches 99%, and the removal rate of arsenic reaches 95%.

The zero-valent iron of the above embodiment is micron-sized zero-valent iron, the particle size is greater than 5 microns, and the source is: factory scrap iron, commercial zero-valent iron powder and the like.

Claims

1. A zero-valent iron material Fe @ iron fluoride is characterized in that: the surface layer of the zero-valent iron material is an iron fluoride layer which replaces iron oxide of a zero-valent iron shell layer, and the iron fluoride comprises Fe₃F₈•2H₂O and Fe₂F₅•2H₂O。

2. A method of preparing the zero-valent iron material Fe @ iron fluoride of claim 1, wherein: the method comprises the following steps: heating hydrofluoric acid solution and zero-valent iron to react for 2-7h at 50-120 ℃, and performing post-treatment to obtain a zero-valent iron material Fe @ iron fluoride, wherein the concentration of the hydrofluoric acid is 0.1-2M, and the using amount of the zero-valent iron is 80-400 g/L.

3. The method of claim 2, wherein: the post-treatment comprises the following steps: after solid-liquid separation, washing with deionized water and ethanol respectively, and finally drying in a vacuum drying oven.

4. The method of claim 2, wherein: the zero-valent iron is micron-sized zero-valent iron; the hydrofluoric acid is from hydrofluoric acid wastewater which is sold in the market or discharged in the photovoltaic industry.

5. A method of removing heavy metal contamination using the zero-valent iron material Fe @ iron fluoride of claim 1.

6. The method of claim 5, wherein: the dosage of the zero-valent iron material Fe @ iron fluoride is 0.2-1 g/L.

7. The method of claim 5, wherein: said heavy metal contamination comprises chromium and arsenic; the heavy metal pollution concentration is 1-10 mg/L; stirring is carried out in the removing process.