CN107934976A - Method that silicate type apatite is prepared by smelting iron and steel slag and application thereof - Google Patents

Abstract

The invention discloses a method for preparing silicate-type apatite from iron and steel smelting slag and its application, and studies the adsorption effect of the silicate-type apatite on heavy metal ions in waste water, belonging to the field of environmental protection. The preparation method of the present invention mainly includes the following steps: firstly place iron and steel smelting slag powder and phosphate in deionized water respectively, mix them, and stir continuously; secondly, adjust the pH of the mixed solution to alkaline with lye; Liquid is synthesized by hydrothermal method to form silicate apatite; finally, deionized water is washed to neutral to obtain silicate apatite adsorbent, which can adsorb heavy metal ions. The preparation method of the invention is simple, the sources of raw materials are extensive, the environment is friendly, the adsorption effect is excellent, and it is easy to popularize.

Description

Method for preparing silicate apatite from iron and steel smelting slag and its application

technical field

The invention relates to a method for preparing silicate-type apatite from iron and steel smelting slag and its application in absorbing heavy metal ions in waste water, belonging to the field of environmental protection.

Background technique

Electroplating wastewater is one of the most harmful industrial wastewater to the environment and human health. Electroplating is usually carried out in a strong acid solution, and the discharged heavy metal ions such as chromium, nickel, copper, zinc, lead, silver, and gold enter the atmosphere, water, and soil. Heavy metal ions and their compounds can accumulate and enrich in animals and plants such as crops, fish, and animals, and cause serious harm to humans through accumulation in drinking water and food chains, bioconcentration, and biomagnification. Therefore, there is an urgent need to develop new environmentally friendly materials that can effectively remove heavy metal ions from electroplating wastewater.

At present, the emissions of mercury, cadmium, hexavalent chromium, total chromium, lead and arsenic in industrial wastewater are 0.7 tons, 16.9 tons, 34.8 tons, 131.8 tons, 71.8 tons and 109.2 tons respectively. The treatment methods of heavy metal wastewater mainly include: chemical precipitation method, physical treatment method and biological treatment method. (1) Physical treatment methods mainly include adsorption method, ion exchange method and membrane separation method. Activated carbon powder is the most commonly used adsorbent, which has strong adsorption capacity and high removal rate, but it is not easy to separate from water due to its low density. Although the ion exchange method and membrane separation method are effective in removing heavy metal ions, the recovery cost is high and the equipment cost is expensive. (2) Biological treatment, mainly including biological flocculation, biochemical and phytoremediation. Although the biological treatment method has excellent characteristics such as safety, non-toxicity, and no secondary pollution, it is not suitable for the treatment of strongly acidic electroplating wastewater. (3) The chemical precipitation method is to make heavy metal ions into insoluble substances through chemical reactions and precipitate and separate them. The method is simple and convenient to operate, and is widely used in wastewater treatment.

Chinese patent CN 106984290 A adopts the method of electrostatic droplet method and cooling solidification bath to combine sodium alginate magnetic composite microspheres with chitosan to adsorb heavy metal ions. Although it has strong adsorption performance, it has poor operability and is not suitable for promotion. ; Chinese patent CN 105521759 A uses egg shells as raw materials, and uses biomass organic phytic acid as a phosphorus source to prepare a high-carbonate doped carbon hydroxyapatite adsorbent. Adding organic substances during the preparation process will easily cause secondary damage to the environment. Pollution; Chinese Patent No. CN 102908998 A discloses a preparation method of a xanthic acid-based perforated glucose gel adsorbent, the gel prepared by the method is used to adsorb heavy metals, and has the advantages of high adsorption capacity and degradability, but The material has poor mechanical properties and is not easy to be used on a large scale.

Hydroxyapatite, Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , is a typical structural representative of the apatite family, and its crystal is hexagonal. Ca ²⁺ in the molecule is easily exchanged by Cd ²⁺ , Hg ²⁺ , Cr ²⁺ , Ba ²⁺ , Pb ²⁺ and other heavy metal ions. The fine powder of low crystallinity HA has a large specific surface area. Therefore, apatite can be used as a high-quality inorganic ion lattice adsorption and exchange material for wastewater treatment and recovery of valuable elements. The main mechanisms for the removal of heavy metal ions by apatite include adsorption, surface complexation, dissolution-precipitation, and ion exchange between heavy metal ions and the crystal lattice. Generally speaking, heavy metal ions are adsorbed and solidified in the middle of the lattice without secondary pollution.

There are many ways to prepare apatite, mainly including mechanochemical method, chemical precipitation method, hydrothermal method, sol-gel method, etc. Among them, Han Jimei et al. used Ca(NO ₃ ) ₂ and Na ₃ PO ₄ at normal pressure, 145 Under the condition of ℃, nano _- hydroxyapatite _{crystals were} hydrothermally synthesized, and its composition, structure and morphology _were very similar to tooth inorganic substances _; Earl et al _. The raw materials were subjected to hydrothermal conditions for 24 hours to synthesize nanorod-shaped hydroxyapatite with a diameter of _10-60nm and a length of _{100-500nm ;} HA powder with good dispersibility and end surface particle size below 100nm.

Contents of the invention

The purpose of the present invention is to use iron and steel smelting slag as raw material to prepare silicate apatite by hydrothermal synthesis, and to absorb heavy metal ions in waste water. The silicate-type apatite prepared by the invention has good dispersibility, uniform particle size and excellent adsorption performance, and is used for adsorbing heavy metal ions in waste water.

The present invention is achieved through the following technical solutions:

The invention provides a method for preparing silicate apatite from iron and steel smelting slag, which comprises the following steps:

After dissolving iron and steel smelting slag powder and phosphate with deionized water respectively, after mixing according to the molar ratio of calcium element and phosphorus element as (1-2):1, the pH value is adjusted to be alkaline with lye;

After performing the hydrothermal reaction, cool naturally to room temperature, collect the precipitate by filtration, wash with deionized water until neutral, and then dry to obtain the silicate apatite.

As a preferred solution, the iron and steel smelting slag contains the following components by weight percentage:

As a preferred solution, the phosphate is one or more of diammonium hydrogen phosphate, ammonium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, and disodium hydrogen phosphate.

As a preferred solution, the temperature of the hydrothermal reaction is 120-180° C., and the time of the hydrothermal reaction is 3-24 hours.

As a preferred solution, the lye is at least one of ammonia water, sodium hydroxide solution, and potassium hydroxide solution.

A silicate apatite prepared by the aforementioned method.

A use of the aforementioned silicate-type apatite in adsorbing heavy metal ions in wastewater.

The silicate apatite Ca ₁₀ (PO ₄ ) _x (SiO ₃ ) _6-x (OH) ₂ of the invention is prepared from steel smelting slag in a factory as a raw material, and effectively adsorbs heavy metal ions in waste water. That is to say, the recycling of factory waste residues is realized, and the pollution of heavy metal ions in industrial wastewater to the environment is reduced, turning waste into treasure.

Compared with the prior art, the present invention has the following beneficial effects:

1. The raw material comes from factory waste residue, which has a wide range of sources, low cost, turns waste into treasure, and improves environmental protection issues;

2. Silicate-type apatite prepared by hydrothermal synthesis method has low crystallinity, no agglomeration in the reaction process, no need for high-temperature burning treatment, obvious lattice defects, and is conducive to the removal of heavy metals;

3. The preparation process of the silicate-type apatite does not add an organic template agent, and has no toxic and side effects;

4. The nano-hydroxyapatite prepared by the present invention has appropriate mechanical properties and good processability. When treating heavy metals in wastewater, it will not cause secondary pollution to the environment, so that it can be widely used in the field of water treatment .

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is the X-ray diffraction spectrum of iron and steel smelting slag in the embodiment 1 of the present invention;

Fig. 2 is the X-ray diffraction spectrum of the silicate apatite prepared as raw material from iron and steel smelting slag in Example 1 of the present invention;

Fig. 3 is the elemental analysis diagram of the iron and steel smelting slag of embodiment 1 of the present invention;

Fig. 4 is the scanning electron micrograph of silicate-type apatite obtained in Example 1 of the present invention after adsorbing lead ions;

Fig. 5 is the amount of adsorption of lead ions in different pH solutions by silicate apatite prepared in Example 1 of the present invention;

Fig. 6 is the adsorption amount of silicate apatite prepared in Example 1 of the present invention to different concentrations of lead ions.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1

(1) Take 10g of iron and steel smelting slag powder and 5.01g of diammonium hydrogen phosphate (according to the Ca/P molar ratio of 1.67/1) at room temperature, put them into a 250ml beaker, first add 50ml of deionized water to dissolve, and use a magnetic stirrer Stir while adjusting the pH of the system to 10 with 1 mol/L NaOH solution, and stir for 30 min.

(2) Transfer the uniformly mixed solution to a high-pressure reactor, put it into an oven, and perform a hydrothermal reaction at a temperature of 120° C. and a reaction time of 8 hours.

(3) After the reaction, the autoclave was taken out of the oven, naturally cooled to room temperature, filtered and washed until the pH was 7.4, and a silicate apatite precipitate was obtained, which was dried in an oven at 60°C to obtain a sample.

The iron and steel smelting slag in embodiment 1 is characterized, obtain X-ray diffraction spectrum (XRD) and component analysis figure, are shown in Fig. 1 and Fig. 3 respectively, and the form of the prepared silicate apatite The appearance and composition are characterized, and the obtained X-ray diffraction pattern (XRD) and scanning electron microscope image (SEM) are shown in Figure 2 and Figure 4 respectively.

It can be seen from the XRD spectrum in Figure 2 that the crystal form of silicate apatite is hexagonal. It can be seen from the SEM image of Figure 4 that the obtained silicate apatite has good dispersibility.

Example 2

(1) Take 10g of iron and steel smelting slag powder at room temperature, 25.8g of disodium hydrogen phosphate dodecahydrate (according to the Ca/P molar ratio of 1:1, put them into a 250ml beaker, first add 50ml of deionized water to dissolve, and stir with a magnetic force Stir with a device while adjusting the pH of the system to 12 with a 1mol/L KOH solution, and stir for 60 minutes.

(2) Transfer the uniformly mixed solution to a high-pressure reactor, put it into an oven, and perform a hydrothermal reaction at a temperature of 140° C. and a reaction time of 6 hours.

(3) After the reaction, the autoclave was taken out of the oven, cooled naturally to room temperature, filtered and washed until the pH was 7.4, and a silicate apatite precipitate was obtained, which was dried in an oven at 80°C to obtain a sample.

Example 3

(1) Take 10g of iron and steel smelting slag powder and 6.48g of sodium dihydrogen phosphate dihydrate (2:1 according to the molar ratio of Ca/P) at room temperature, put them into a 250ml beaker, first add 50ml of deionized water to dissolve, and stir with a magnetic force Stir with a device while adjusting the pH of the system to 14 with a 1mol/L KOH solution, and stir for 60 minutes.

(2) Transfer the uniformly mixed solution to a high-pressure reactor, put it into an oven, and perform a hydrothermal reaction at a temperature of 180° C. and a reaction time of 3 hours.

(3) After the reaction, the autoclave was taken out of the oven, cooled naturally to room temperature, filtered and washed until the pH was 7.4, and a silicate apatite precipitate was obtained, which was dried in an oven at 100°C to obtain a sample.

Example 4

(1) Take 10g of iron and steel smelting slag powder and 5.17g of ammonium dihydrogen phosphate (1.6 according to the Ca/P molar ratio) at room temperature, put them in a 250ml beaker, add 50ml of deionized water to dissolve, and stir with a magnetic stirrer, At the same time, adjust the pH value of the system to 11 with 1 mol/L ammonia solution, and stir for 2 hours.

(2) Transfer the uniformly mixed solution to a high-pressure reactor, put it into an oven, and perform a hydrothermal reaction at a temperature of 120° C. and a reaction time of 24 hours.

(3) After the reaction, the autoclave was taken out of the oven, naturally cooled to room temperature, filtered and washed until the pH was 7.4, and a silicate apatite precipitate was obtained, which was dried in an oven at 60°C to obtain a sample.

Example 5

The silicate-type apatite obtained in embodiment 1 is carried out the adsorption experiment of heavy metal ion:

(1) Weigh 0.5g of silicate-type apatite, lead ion concentration is 400mg/L, pH=4.0 waste water, under 20 ℃, under 500rpm stirring rate, carry out adsorption, regularly sample, use EDTA solution of 1.0000mmol/L Titrate the concentration of remaining lead ions in the solution until adsorption equilibrium is reached.

Drawing and analysis are carried out to embodiment 5 adsorption lead ion experiment gained data, to lead ion adsorption curve as shown in Figure 5, with respect to the adsorption effect of existing adsorbent material to heavy metal in waste water, the nano hydroxyl prepared by the present invention The adsorption effect of apatite on heavy metal ions has been greatly improved.

Example 6

The silicate-type apatite obtained in embodiment 1 is carried out the adsorption experiment of heavy metal ion:

(1) Weigh 0.5g of silicate-type apatite, lead ion concentration is 800mg/L, pH=5.5 waste water, under 20 ℃, under 500rpm stirring rate, carry out adsorption, regularly sample, use EDTA solution of 1.0000mmol/L Titrate the concentration of remaining lead ions in the solution until adsorption equilibrium is reached.

The data obtained in the experiment of adsorbing lead ions in Example 6 were drawn and analyzed, and the graph of the adsorption amount of lead ions is shown in FIG. 6 .

In summary, these are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. All equivalent changes and modifications are made in accordance with the shape, structure, characteristics and spirit described in the scope of the claims of the present invention. , should be included in the scope of the claims of the present invention.

Claims (7)

1. A method for preparing silicate-type apatite by iron and steel smelting slag, is characterized in that, comprises the steps: After dissolving iron and steel smelting slag powder and phosphate with deionized water respectively, after mixing according to the molar ratio of calcium element and phosphorus element as (1-2):1, the pH value is adjusted to be alkaline with lye; After carrying out the hydrothermal reaction, cool naturally to room temperature, filter and collect the filter residue, wash until neutral and then dry to obtain the silicate apatite. 2. the method for preparing silicate apatite by iron and steel smelting slag as claimed in claim 1, is characterized in that, comprises the following components by weight percentage in the described iron and steel smelting slag: 3. the method for preparing silicate apatite by iron and steel smelting slag as claimed in claim 1, is characterized in that, described phosphate is diammonium hydrogen phosphate, ammonium dihydrogen phosphate, dipotassium hydrogen phosphate, dihydrogen phosphate One or more of potassium, sodium dihydrogen phosphate, and disodium hydrogen phosphate. 4 . The method for preparing silicate apatite from iron and steel smelting slag according to claim 1 , wherein the temperature of the hydrothermal reaction is 120-180° C., and the time of the hydrothermal reaction is 3-24 hours. 5 . The method for preparing silicate apatite from iron and steel smelting slag as claimed in claim 1 , wherein the lye is at least one of ammonia water, sodium hydroxide solution, and potassium hydroxide solution. 6. A silicate apatite prepared by the method according to any one of claims 1-5. 7. A use of the silicate-type apatite as claimed in claim 6 in adsorbing heavy metal ions in waste water.