阅读说明：本技术 一种过渡金属磷化物修饰的纳米铁复合材料及其制备方法和应用 (Transition metal phosphide-modified nano-iron composite material and preparation method and application thereof ) 是由 王海涛 展思辉 李铁龙 于 2021-07-05 设计创作，主要内容包括：本发明公开了一种过渡金属磷化物修饰的纳米铁复合材料及其制备方法和应用。所述复合材料的制备方法包括以下步骤：将过渡金属磷化物和零价铁按照质量比为1:(5～1000)的比例混合均匀；在惰性或者还原性气氛下,将得到的混合物进行球磨,得到过渡金属磷化物修饰的纳米铁复合材料。本申请将金属磷化物负载到零价铁表面,金属磷化物能够催化有机氯化学物的还原,大大提高了纳米铁材料的还原脱氯性能,可用于处理和修复有机氯代烃污染的土壤和地下水。(The invention discloses a transition metal phosphide-modified nano-iron composite material and a preparation method and application thereof. The preparation method of the composite material comprises the following steps: uniformly mixing the transition metal phosphide and zero-valent iron according to the mass ratio of 1 (5-1000); and carrying out ball milling on the obtained mixture in an inert or reducing atmosphere to obtain the transition metal phosphide modified nano-iron composite material. The application loads the metal phosphide on the surface of zero-valent iron, and the metal phosphide can catalyze the reduction of organic chlorinated chemicals, thereby greatly improving the reduction dechlorination performance of the nano-iron material and being capable of being used for treating and repairing soil and underground water polluted by organic chlorinated hydrocarbons.)

1. A preparation method of a transition metal phosphide-modified nano-iron composite material is characterized by comprising the following steps: the method comprises the following steps:

s1, uniformly mixing the transition metal phosphide and the zero-valent iron according to the mass ratio of 1 (5-1000);

and S2, ball-milling the mixture obtained in the step S1 in an inert or reducing atmosphere to obtain the transition metal phosphide-modified nano-iron composite material.

2. The method for preparing the transition metal phosphide-modified nano-iron composite material as claimed in claim 1, wherein the method comprises the following steps: in step S1, the transition metal phosphide is one or more of NiP, CoP, MoP and WP.

3. The method for preparing the transition metal phosphide-modified nano-iron composite material as claimed in claim 1, wherein the method comprises the following steps: in step S1, the mass ratio of the transition metal phosphide to the nano-iron is 1 (5-500).

4. The method for preparing the transition metal phosphide-modified nano-iron composite material as claimed in claim 3, wherein the method comprises the following steps: in step S1, the mass ratio of the transition metal phosphide to the nano-iron is 1: 150.

5. The method for preparing the transition metal phosphide-modified nano-iron composite material as claimed in claim 1, wherein the method comprises the following steps: in step S2, the inert atmosphere is one or more of nitrogen, argon, and helium; the reducing atmosphere is one or more of nitrogen, argon and helium containing reducing gas, and the reducing gas is one or two of hydrogen and methane.

6. The method for preparing the transition metal phosphide-modified nano-iron composite material as claimed in claim 1, wherein the method comprises the following steps: in step S2, the ball milling mode is that the ball milling is performed in a positive and negative alternate operation mode, the frequency is that the ball milling is turned once every 20-30 min, the turning is performed for 40-50 times in total, and the ball milling time is 5-30 h.

7. A transition metal phosphide-modified nano-iron composite material prepared by the preparation method as set forth in any one of claims 1 to 6.

8. Use of the transition metal phosphide-modified nano-iron composite material as defined in claim 7 for remediation of organochlorine-contaminated soil and groundwater environments.

Technical Field

The invention relates to the technical field of environmental remediation and material preparation, in particular to a transition metal phosphide modified nano-iron composite material and a preparation method and application thereof.

Background

Organochlorine compounds such as trichloroethylene are colorless, volatile, and poorly water soluble liquids. Organochlorine compounds are widely used industrial raw materials mainly as extractants for fats, perfumes and paraffins, solvents for various natural rubbers, plastics and asphalts, petroleum refining, printing inks, binder manufacture, and refrigerator refrigerants and clothes dry cleaners, etc. The organic chlorine compound has obvious biological toxicity, and can cause rash when being contacted with skin, liver function damage, cancer and the like when being contacted for a long time.

As the organic chlorine is a common solvent, the organic chlorine can enter the environment through various ways, is one of the most widely distributed pollutants in the current environment, and is also a pollutant which is focused on in fields of industries such as dry cleaning, chemical engineering, pharmacy and the like. Since the organochlorine compound is hardly soluble in water, it has high mobility in the aqueous layer. And most of the organochlorine compounds have a relative density greater than that of water, have strong vertical migration in groundwater, and easily form DNAPL (chemical substances having a density greater than that of water) on a water-barrier layer. DNAPL is slowly released into underground water after being formed, so that the difficulty and cost of underground water remediation are increased.

Zero valent iron has been used to remediate organochlorine compounds such as trichloroethylene contaminated water or soil. As an important reducing agent, the nano zero-valent iron material has strong underground water mobility, can be directly injected underground and diffused with underground water to finish underground water remediation. Therefore, compared with the reactive permeable wall prepared by macroscopic materials such as iron chips, iron shavings and the like, the construction cost is obviously reduced. But the zero-valent iron material has strong reducibility and can reduce water to generate hydrogen. Since hydrogen cannot effectively reduce organic chloride and zero-valent iron material lacks selective adsorption of organic chloride, a large portion of zero-valent iron material reacts with water to generate hydrogen, which is wasted.

In order to promote the reduction dechlorination performance of zero-valent iron, researchers try to modify metal palladium on the surface of the zero-valent iron, the metal palladium can crack hydrogen generated by corrosion of the zero-valent iron into active hydrogen atoms, the reduction performance of the active hydrogen atoms is very high, and the dechlorination efficiency of trichloroethylene can be improved by one order of magnitude. However, the high price of palladium metal undoubtedly results in increased repair costs.

Disclosure of Invention

The invention provides a transition metal phosphide-modified nano-iron composite material, and a preparation method and application thereof, aiming at solving the technical problems.

The invention is realized by the following technical scheme.

A preparation method of a transition metal phosphide-modified nano-iron composite material comprises the following steps:

s1, uniformly mixing the transition metal phosphide and the zero-valent iron according to the mass ratio of 1 (5-1000);

and S2, ball-milling the mixture obtained in the step S1 in an inert or reducing atmosphere to obtain the transition metal phosphide-modified nano-iron composite material.

Further, in step S1, the transition metal phosphide is one or more of NiP, CoP, MoP and WP.

Further, in step S1, the mass ratio of the transition metal phosphide to the nano-iron is 1 (5-500).

Further, in step S1, the mass ratio of the transition metal phosphide to the nano-iron is 1: 150.

Further, in step S2, the inert atmosphere is one or more of nitrogen, argon and helium; the reducing atmosphere is one or more of nitrogen, argon and helium containing reducing gas, and the reducing gas is one or two of hydrogen and methane.

Further, in step S2, the ball milling mode is forward and reverse alternate ball milling, the frequency is once turning every 20-30 min, the turning is performed for 40-50 times, and the ball milling time is 5-30 h.

A transition metal phosphide modified nano-iron composite material prepared by the preparation method.

The application of the transition metal phosphide modified nano-iron composite material in repairing soil and underground water environment polluted by organic chlorohydrocarbon.

The present application has the following advantageous effects.

The invention can realize the mixed doping of the metal phosphide and the zero-valent iron on the nanoscale by a ball milling method, thereby improving the binding force of the phosphide on the surface of the zero-valent iron and the coating uniformity. The transition metal phosphide-modified nano-iron composite material prepared by the invention utilizes metal phosphide to catalyze and generate active hydrogen atoms, so that the reduction dechlorination speed of organic chloride compounds is improved, and the electron utilization efficiency of zero-valent iron is effectively improved. And compared with metal palladium, the metal phosphide has low price and effectively reduces the repair cost.

Drawings

FIG. 1 is an SEM image of a composite material (CoP/nZVI) prepared in example 4 of the present invention;

FIG. 2 is a TEM image of a composite material (CoP/nZVI) prepared in example 4 of the present invention;

FIG. 3 is a graph showing the results of experiments conducted to remove trichloroethylene by reductive dechlorination from materials obtained in example 4 of the present invention and comparative example 1.

Detailed Description

Example 1

A preparation method of a transition metal phosphide-modified nano-iron composite material comprises the following steps:

s1, weighing 1g of cobalt phosphide and 5 g of reduced iron powder, and uniformly mixing;

and S2, placing the mixture into a ball milling tank for ball milling, filling nitrogen for protection, adopting mechanical ball milling, alternately running forward and backward, turning once every 20 minutes, carrying out ball milling for 16 hours, and turning for 48 times to obtain the transition metal phosphide modified nano-iron composite material.

Example 2

A preparation method of a transition metal phosphide-modified nano-iron composite material comprises the following steps:

s1, weighing 1g of cobalt phosphide and 1000 g of reduced iron powder, and uniformly mixing;

and S2, placing the mixture into a ball milling tank for ball milling, filling nitrogen for protection, adopting mechanical ball milling, alternately running forward and backward, turning once every 30 minutes, ball milling for 20 hours, and turning 40 times to obtain the transition metal phosphide modified nano-iron composite material.

Example 3

A preparation method of a transition metal phosphide-modified nano-iron composite material comprises the following steps:

s1, weighing 1g of cobalt phosphide and 500g of reduced iron powder, and uniformly mixing;

and S2, placing the mixture into a ball milling tank for ball milling, filling nitrogen for protection, adopting mechanical ball milling, alternately running forward and backward, turning once every 30 minutes, performing ball milling for 24 hours, and turning for 48 times to obtain the transition metal phosphide modified nano-iron composite material.

Example 4

A preparation method of a transition metal phosphide-modified nano-iron composite material comprises the following steps:

s1, weighing 1g of cobalt phosphide and 100 g of reduced iron powder, and uniformly mixing;

and S2, placing the mixture into a ball milling tank for ball milling, filling nitrogen for protection, adopting mechanical ball milling, alternately running forward and backward, turning once every 30 minutes, carrying out ball milling for 24 hours, and turning for 48 times to obtain the transition metal phosphide modified nano-iron composite material (CoP/nZVI).

The transition metal phosphide-modified nano-iron composite material prepared in the example was subjected to SEM and TEM detection, and the results are shown in fig. 1 and 2.

Comparative example 1

A preparation method of a nano zero-valent iron reduction material comprises the following steps:

will be charged with 100 mL of 0.05 mol/L FeCl₃Adding the aqueous solution into a three-neck flask, aerating with nitrogen for 30min to remove dissolved oxygen in the system, adding 50 mL of 0.4 mol/L NaBH with pH 12₄Dropwise adding the mixture into a three-neck flask, and obtaining the nano zero-valent iron reduced material (nZVI) after the reduction reaction is finished.

Performance detection

The materials prepared in the example 4 and the comparative example 1 are subjected to a reduction dechlorination experiment of trichloroethylene, and the specific experiment contents are as follows:

the reactions were all carried out in 40mL brown sealed bottles, purged with nitrogen before use. The newly synthesized transition metal phosphide-modified nano-iron composite material and nano-zero-valent iron were introduced into a 40mL brown sealed bottle via a vacuum line, a trichloroethylene standard solution was injected to a concentration of 15 mg/L, and the sealed reaction bottle was put into a gas bath constant temperature oscillator for oscillation reaction at a rotation speed of 250 rpm. And extracting a sample at a preset time, and detecting the concentration of the trichloroethylene by adopting gas chromatography.

As shown in FIG. 3, the removal rate of trichloroethylene by the composite material (CoP/nZVI) prepared in example 4 after 15 min reaches 100%. While the removal rate of trichloroethylene by the common nano zero-valent iron (nZVI) prepared in the comparative example 1 is only 7 percent. Therefore, the reduction dechlorination effect of the transition metal phosphide modified nano-iron composite material prepared by the method is greatly improved.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.