阅读说明：本技术 一种基于红土镍铁矿去除水中重金属污染的方法 (Method for removing heavy metal pollution in water based on laterite-nickel iron ore ) 是由 金杰 鲍腾 王晓飞 慈娟 吴克 俞志敏 于 2019-11-06 设计创作，主要内容包括：本发明公开一种基于红土镍矿去除水中重金属污染的方法,包括如下步骤：步骤S1,制备纳米零价铁镍复合材料；步骤S2,将所述纳米零价铁镍复合材料加入含重金属污染的工业废水中,常温下反应后,经静置、沉淀后进行固液分离。本发明制备的所述纳米零价铁镍复合材料,具有丰富的纳米孔、微米孔结构,进而具有更高的化学活性和催化活性,将其作为吸附剂处理含重金属废水时,污染物去除率高,且便于固液分离。(The invention discloses a method for removing heavy metal pollution in water based on laterite-nickel ore, which comprises the following steps: step S1, preparing a nano zero-valent iron-nickel composite material; and step S2, adding the nano zero-valent iron-nickel composite material into industrial wastewater containing heavy metal pollution, reacting at normal temperature, standing, precipitating, and performing solid-liquid separation. The nano zero-valent iron-nickel composite material prepared by the invention has abundant nano-pore and micro-pore structures, further has higher chemical activity and catalytic activity, and has high pollutant removal rate and is convenient for solid-liquid separation when being used as an adsorbent to treat heavy metal-containing wastewater.)

1. A method for removing heavy metal pollution in water based on laterite-nickel ore is characterized by comprising the following steps:

step S1, preparing a nano zero-valent iron-nickel composite material;

and step S2, adding the nano zero-valent iron-nickel composite material into industrial wastewater containing heavy metal pollution, reacting at normal temperature, standing, precipitating, and performing solid-liquid separation.

2. The method for removing heavy metal pollution in water based on lateritic nickel ore according to claim 1, characterized in that the nano zero-valent iron-nickel composite material is prepared by using borohydride as a reducing agent to perform liquid phase reduction reaction with lateritic nickel ore, and the nano zero-valent iron-nickel composite material contains nano zero-valent iron and nano zero-valent nickel.

3. The method for removing heavy metal pollution in water based on lateritic nickel ore according to claim 2, characterized in that the preparation steps of the nano zero-valent iron-nickel composite material are as follows:

step S11, crushing and screening the natural laterite-nickel ore to obtain a granular material;

step S12, carrying out activation pretreatment on the granular material to obtain laterite-nickel ore powder;

step S13, adding borohydride salt into the laterite-nickel ore powder to carry out liquid phase reduction reaction, and obtaining the nano zero-valent iron-nickel composite material.

4. The method for removing heavy metal pollution in water based on lateritic nickel ores as set forth in claim 3, wherein the particle size of the particulate material is < 0.0374 mm.

5. The method for removing heavy metal pollution in water based on lateritic nickel ore according to claim 3, characterized in that the process of the activation pretreatment is as follows:

step S121, placing the particle materials into an ethanol solution and stirring to enable the particle materials to be uniformly dispersed;

step S122, filtering and centrifuging the particle material, and washing the particle material for a plurality of times by using deionized water;

and S123, drying the granular material in an oven to obtain the laterite-nickel iron ore powder.

6. The method for removing heavy metal pollution in water based on lateritic nickel ore according to claim 3, characterized in that the time of the liquid phase reduction reaction is set to 2-10 h.

7. The method for removing heavy metal pollution in water based on lateritic nickel ore according to claim 6, characterized in that the borohydride salt includes sodium borohydride or potassium borohydride.

8. The method for removing heavy metal pollution in water based on lateritic nickel ore according to any one of claims 1 to 7, characterized in that the nano zero-valent iron-nickel composite material is added in an amount of 0.01g to 5g per 1L of wastewater.

9. The method for removing heavy metal pollution in water based on lateritic nickel ore according to claim 8, characterized in that the reaction time is set to 5-30 min in the step S2.

10. The method for removing heavy metal pollution in water based on lateritic nickel ore according to claim 8, characterized in that the concentration of the industrial wastewater is less than or equal to 500mg/L and the pH value is 5-9.

Technical Field

The invention relates to the technical field of water treatment, in particular to a method for removing heavy metal pollution in water based on laterite-nickel ore.

Background

The method has the advantages that the problem of water environment is prominent in the day ahead, wherein the wastewater containing heavy metals is one of the industrial wastewater which has the most serious pollution to the water environment and the greatest harm to human beings, the nano zero-valent iron has strong reducibility and adsorbability and is widely applied to the treatment of the wastewater containing heavy metal pollution, the nano zero-valent iron is synthesized by ferrous ions in the prior art, but the nano iron prepared by the method has low activity and poor wastewater treatment effect, is easy to agglomerate in the process of treating the heavy metal wastewater, is easy to corrode in a water body, has poor stability and the like, and further limits the application of the nano zero-valent iron in practice.

In view of the above-mentioned drawbacks, the inventors of the present invention have finally obtained the present invention through a long period of research and practice.

Disclosure of Invention

In order to solve the technical defects, the technical scheme adopted by the invention is to provide a method for removing heavy metal pollution in water based on laterite-nickel ore, which comprises the following steps:

step S1, preparing a nano zero-valent iron-nickel composite material;

and step S2, adding the nano zero-valent iron-nickel composite material into industrial wastewater containing heavy metal pollution, reacting at normal temperature, standing, precipitating, and performing solid-liquid separation.

Preferably, the nano zero-valent iron-nickel composite material is prepared by performing liquid phase reduction reaction on laterite-nickel ore by using borohydride as a reducing agent, and the nano zero-valent iron-nickel composite material contains nano zero-valent iron and nano zero-valent nickel.

Preferably, the preparation steps of the nano zero-valent iron-nickel composite material are as follows:

step S11, crushing and screening the natural laterite-nickel ore to obtain a granular material;

step S12, carrying out activation pretreatment on the granular material to obtain laterite-nickel ore powder;

step S13, adding borohydride salt into the laterite-nickel ore powder to carry out liquid phase reduction reaction, and obtaining the nano zero-valent iron-nickel composite material.

Preferably, the particle size of the particulate material is < 0.0374 mm.

Preferably, the process of the activation pretreatment is as follows:

step S121, placing the particle materials into an ethanol solution and stirring to enable the particle materials to be uniformly dispersed;

step S122, filtering and centrifuging the particle material, and washing the particle material for a plurality of times by using deionized water;

and S123, drying the granular material in an oven to obtain the laterite-nickel iron ore powder.

Preferably, the time of the liquid phase reduction reaction is set to be 2h-10 h.

Preferably, the borohydride salt comprises sodium borohydride or potassium borohydride.

Preferably, the addition amount of the nano zero-valent iron-nickel composite material is 0.01-5 g per 1L of wastewater.

Preferably, the reaction time in step S2 is set to be 5min to 30 min.

Preferably, the concentration of the industrial wastewater is less than or equal to 500mg/L, and the pH value is 5-9.

Compared with the prior art, the invention has the beneficial effects that:

the nanometer zero-valent iron-nickel composite material prepared by adopting the natural laterite-nickel ore has rich nanometer hole and micron hole structures, and fine nickel metal particles are uniformly distributed in the nanometer zero-valent iron-nickel composite material, and can be used as catalytic active sites to form a micro primary battery to generate hole charges, accelerate the corrosion on the nanometer zero-valent iron-nickel, and improve the catalytic oxidation capability of the nanometer zero-valent iron-nickel, so that compared with a nanometer oxide synthesized by adopting iron salt in the prior art, the nanometer zero-valent iron-nickel composite material has higher chemical activity and catalytic activity;

2, the nano iron-nickel bimetal in the nano zero-valent iron-nickel composite material is uniformly dispersed, so that the problem of agglomeration and passivation of nano particles is effectively solved, and the removal effect of the nano zero-valent iron-nickel composite material on organic pollutants is improved;

3, the nano zero-valent iron-nickel composite material is prepared by adopting a liquid phase reduction method, the synthesis process is simple and easy to control, the reaction condition is mild, the reaction efficiency is high, the operation is simple, safe and reliable, the production cost is low, and the popularization and the application are facilitated;

4, the invention utilizes the nanometer zero-valent iron-nickel composite material as an adsorbent to treat wastewater containing heavy metals, not only has simple water treatment method and high heavy metal removal efficiency, but also is beneficial to solid-liquid separation during water treatment because the nanometer zero-valent iron-nickel composite material has superparamagnetic property.

Drawings

FIG. 1 is an XRD test chart of a natural laterite-nickel ore and nano zero-valent iron-nickel composite material in the invention;

fig. 2 is an SEM image of natural lateritic nickel ore in the present invention;

FIG. 3 is an SEM image of the nano zero-valent iron-nickel composite material in the invention;

FIG. 4 shows the removal rate of cadmium when the nano zero-valent iron-nickel composite material of the fourth embodiment of the present invention and the prior art are used for treating cadmium-containing industrial wastewater respectively;

FIG. 5 shows the removal rate of heavy metal pollutants when the nano zero-valent iron-nickel composite material is used for treating industrial wastewater with different pH values in example V of the invention;

FIG. 6 shows the removal rate of cadmium in wastewater treated by the nano zero-valent iron-nickel composite material at different temperatures in the sixth embodiment of the present invention;

FIG. 7 shows the removal rate of cadmium when the zero-valent iron-nickel composite material is used for treating wastewater with different concentrations in the seventh embodiment of the invention;

FIG. 8 shows the adsorption amount of cadmium when the zero-valent iron-nickel composite material is used for treating wastewater with different concentrations in the seventh embodiment of the invention.

Detailed Description

The above and further features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

The invention provides a method for removing heavy metal pollution in water based on laterite-nickel ore, which comprises the following steps:

step S1, preparing a nano zero-valent iron-nickel composite material;

and step S2, adding the nano zero-valent iron-nickel composite material into industrial wastewater containing heavy metal pollution, reacting for a certain time at normal temperature, standing for precipitation, and separating. Then, the concentration of heavy metal in the supernatant can be measured to check the removal effect of heavy metal ions.

According to the invention, firstly, the nano zero-valent iron-nickel composite material is prepared, and the specific steps are as follows:

step S1-1, crushing and screening the laterite-nickel ore to obtain a granular material with the grain size less than 0.0374 mm;

step S1-2, carrying out activation pretreatment on the granular material to obtain laterite-nickel ore powder;

and step S1-3, adding a reducing agent into the laterite nickel ore powder to carry out liquid phase reduction reaction.

The laterite-nickel ore comprises laterite in Yunnan, laterite-nickel ore in Philippine or laterite-nickel ore in Indonesia, wherein the grade of iron in the laterite-nickel ore is 50% -80%, and the grade of nickel is 10% -20%. The laterite-nickel ore is crushed to increase the unsmooth degree of the surface of the laterite-nickel ore and further increase the specific surface area of the laterite-nickel ore, the larger the specific surface area of the laterite-nickel ore is, the more dangling bonds on the surface of the laterite-nickel ore are, the larger the adsorption capacity of reaction molecules is, and in addition, the larger the specific surface area of the laterite-nickel ore is, the more catalytic active sites are, so that the catalytic capacity is correspondingly enhanced.

The specific process of pretreatment comprises: placing the crushed granular material into an ethanol solution with the concentration of 90% and stirring for 20-24 hours to enable the granular material to be uniformly dispersed, filtering and centrifuging the granular material, washing the granular material with deionized water for 2-4 times, and then placing the granular material into an oven to be dried to obtain the laterite-nickel iron ore powder;

the specific process of the liquid phase reduction reaction comprises the following steps: adding the laterite-nickel ore powder into a reducing agent with a certain concentration, and continuously stirring for 2-10 hours to ensure that the laterite-nickel ore powder is completely reduced into zero-valent iron and nickel, thus obtaining the nano zero-valent iron-nickel composite material, wherein the nano zero-valent iron-nickel composite material contains nano zero-valent iron and nano zero-valent nickel. The reducing agent is borohydride, specifically, sodium borohydride or potassium borohydride is adopted as the reducing agent, sodium borohydride is more preferable, and the concentration of the reducing agent is preferably set to be 1mol/L-20 mol/L.

Secondly, adding the nano zero-valent iron-nickel composite material into industrial wastewater polluted by heavy metal, fully reacting for 5-30 min at normal temperature, respectively obtaining supernatant and precipitate after precipitation and separation, measuring the concentration of the heavy metal in the supernatant, and recovering the precipitate after vacuum drying.

The industrial wastewater containing heavy metal pollution contains Cd, Cr, Cu, Pb and Zn, the concentration of the industrial wastewater containing heavy metal pollution is less than or equal to 500mg/L, the pH value of the industrial wastewater containing heavy metal pollution is 5-9, and the addition amount of the nano zero-valent iron-nickel composite material is 0.01-5 g per 1L of the industrial wastewater containing heavy metal pollution.

The main action mechanism of the method for preparing the nano zero-valent iron-nickel composite material by using the laterite-nickel ore is shown as the formulas (1) and (2):

4Fe³⁺+3BH₄ ^-+9H₂O→4Fe⁰↓+3H₂BO₃ ^-+12H⁺+6H₂↑(1)

Ni²⁺+2BH₄ ^-+6H₂O→Ni⁰↓+2B(OH)₃+7H₂↑(2)

the iron ions and the nickel ions in the laterite-nickel ore are respectively reduced into zero-valent iron and zero-valent nickel under the action of the borohydride, the reaction mechanism is simple, the product contains boric acid and hydrogen, the components are simple, and no pollution is caused.

XRD tests are respectively carried out on the natural laterite-nickel ore and the nano zero-valent iron-nickel composite material prepared by the invention, and the test results are shown in figure 1, wherein a curve A in figure 1 represents the XRD test results of the natural laterite-nickel ore, a curve B in figure 1 represents the XRD test results of the nano zero-valent iron-nickel composite material, H in figure 1 represents hematite, G represents goethite, and N represents iron-nickel oxide (NiFe) in figure 1₂O₄) M represents Magnetite (Magnetite) and Fe-Ni represents nano-zeroAnd (4) iron-nickel valence. As can be seen from the curve a in fig. 1, the main phases of the natural laterite-nickel ore include goethite, hematite and iron-nickel oxide, while the curve B in fig. 1 can see the diffraction peak of nano zero-valent iron-nickel, the diffraction peak of hematite and the diffraction peak of magnetite, which indicates that the diffraction peaks of goethite and iron-nickel oxide disappear after the natural laterite-nickel ore is subjected to liquid phase reduction reaction, and nano zero-valent iron-nickel composite material, hematite and magnetite are mainly generated.

Scanning Electron Microscope (SEM) tests are carried out on the natural laterite-nickel ore and the nano zero-valent iron-nickel composite material prepared by the invention, the test results are shown in figures 2-3, and as can be seen from figure 2, the natural laterite-nickel ore material has low surface porosity and low active sites. As can be seen from fig. 3, nanoparticles of 80-100nm are formed on the surface of the nano zero-valent iron-nickel composite material, a large number of nano-pore structures exist in the nano zero-valent iron-nickel composite material, and the pores of the nano zero-valent iron-nickel composite material are almost uniformly distributed, so that the nano zero-valent iron-nickel composite material has high activity.

The laterite-nickel ore has abundant reserves, is cheap and easy to obtain, and goethite and hematite crystals in the laterite-nickel ore have abundant multi-level pore structures, have a nano effect, and can effectively improve the chemical activity of the prepared nano zero-valent iron-nickel composite material; in addition, the phenomenon that aluminum replaces iron generally exists in the laterite-nickel ore, the substitution of impurity aluminum can cause more lattice defects in the prepared nano zero-valent iron-nickel composite material, and compared with pure nano iron oxide synthesized by adopting iron salt in the prior art, the nano zero-valent iron-nickel composite material has higher chemical activity.

The nano zero-valent iron-nickel composite material prepared by the invention has small particle size, rich nano-pore and micro-pore structures, and larger specific surface area, wherein the porosity is 80-99%, and the specific surface area is 70-90m²(ii) in terms of/g. In addition, in the nano zero-valent iron-nickel composite material, because the volume fraction of atoms on the surface of the particles is large, considerable surface energy is generated, the number of atoms on the surface of the particles is increased, the specific surface area is increased,the nanometer zero-valent iron-nickel composite material has the advantages that due to the insufficient coordination number of atoms and the existence of unsaturated bonds, the surface of the nanometer zero-valent iron-nickel composite material has many defects, so that the nanometer zero-valent iron-nickel composite material has high activity and is easy to adsorb other atoms to generate chemical reaction, and the activity of the surface atoms not only causes the change of the surface transport and configuration of the nanometer zero-valent iron-nickel composite material, but also causes the change of surface electron spin, conformation and electron energy spectrum, so that the nanometer zero-valent iron-nickel composite material has high chemical activity and catalytic activity.

The nano iron-nickel bimetal in the nano zero-valent iron-nickel composite material prepared by the invention is uniformly dispersed, the problem of agglomeration and passivation of nano particles is effectively solved, and the effect of removing heavy metal pollutants by the nano zero-valent iron-nickel composite material is improved.

The nano zero-valent iron-nickel composite material prepared by the invention has certain magnetism and is convenient for magnetic recovery. In addition, the method for preparing the nano zero-valent iron-nickel composite material by adopting the liquid phase reduction method has the advantages of simple reaction mechanism, mild reaction conditions, high reaction efficiency, simple operation, safety, reliability and low production cost, and is favorable for popularization and application.

In addition, because the nickel content in the natural laterite-nickel ore is high (the nickel content is more than or equal to 10 percent), the nano zero-valent nickel is oxidized into Ni in the water treatment process of the nano zero-valent iron-nickel composite material²⁺Can increase Fe⁰The electron transfer rate synergistically removes micropollutants in the aqueous solution, and the catalytic activity of the nano zero-valent iron-nickel composite material is improved. The specific reaction mechanism is shown as formula (3) to formula (11). The nano zero-valent Fe/Ni preferentially catalyzes and oxidizes the micro-pollutants, more reaction sites are formed on the surface of the material, and a micro primary battery is formed to generate hole charges to accelerate the corrosion of the nano zero-valent Fe/Ni, so that the catalytic oxidation capability of the nano zero-valent Fe/Ni is improved and accelerated, and the degradation of the micro-pollutants is promoted. The introduction of the nano zero-valent Ni metal can effectively improve the catalytic performance of the iron-based material, and when the content of the nano zero-valent Ni is below 20%, the Ni content is improved to effectively improve the catalytic performance of the material, so that the nano zero-valent iron-nickel composite material prepared from natural laterite-nickel ore has the Ni content of about 10-20%The nanometer zero-valent iron-nickel composite material has the highest catalytic activity, and the high catalytic activity is mainly due to the fact that fine Ni metal particles are uniformly distributed in the material and serve as catalytic active sites.

Fe⁰+2H⁺→Fe²⁺+H₂(8)

Fe⁰+2H₂O→Fe²⁺+H₂+2OH^-(9)

2Ni⁰+H₂→2Ni-H (10)

Ni-H→Ni⁰+H^*(11)

Compared with the traditional water treatment method, the nano zero-valent iron-nickel composite material has higher activity, high removal rate of heavy metal pollutants, simple operation process and simple recovery of the nano zero-valent iron-nickel composite material.