Magnetic adsorbent for removing arsenic and antimony by means of adsorption-superconducting magnetic separation and preparation method therefor

Abstract

A magnetic adsorbent, preparation method therefor and application thereof. The magnetic adsorbent is made by loading a weakly material with high adsorption capacity, an iron-based gel, onto a strongly magnetic ferrite material with low adsorption capacity by means of in-situ reaction. The magnetic adsorbent is used for removing heavy metal pollutants and phosphate pollutants from water.

Claims

1. A method for preparing a magnetic adsorbent used for superconducting magnetic separation, comprising the following steps: preparing an iron-based gel by a ferric salt solution and an alkali solution, wherein, dropping the alkali solution slowly into the ferric salt solution and balancing the pH value between 4 to 7.5 under conditions of sufficient stirring, then continuing stirring for 5 to 30 min and standing for 60 min to 24 h to obtain the iron-based gel; loading the obtained iron-based gel on a surface of ferrite by reaction in situ; wherein, the iron-based gel is loaded on the ferrite surface using the following method: (1) adding polyacrylamide solution slowly into ferrite solution under conditions of sufficient stirring, in which the mass ratio of polyacrylamide to ferrite is 1:100 to 1:50000, and reacting for 30 to 120 min to obtain a ferrite suspension; (2) adding a suspension of the iron-based gel slowly into the ferrite suspension obtained in (1) under conditions of sufficient stirring, in which the mass ratio of the iron-based gel and ferrite is 1:10 to 1:500, and reacting for 60 to 240 min.

2. The method of claim 1, wherein the concentration range of ferric salt is 0.5 to 10 mmol/L and the concentration range of OH− in the alkali solution is 0.1 to 10 mol/L.

3. The method of claim 1, wherein the ferric salt is at least one of ferric chloride, ferric sulfate, ferric nitrate, polyferric chloride, polyferric sulfate and polyferric nitrate; the alkali solution is at least one of sodium hydroxide, potassium hydroxide and aqueous ammonia.

4. The method of claim 1, wherein, the ferrite is at least one of manganous ferrite, copper ferrite, magnesium ferrite and ferroferric oxide.

Description

DETAILED DESCRIPTION

(1) The present disclosure will be described below by specific embodiments. Unless otherwise specified, the technical means used in the present disclosure are methods known by those skilled in the art. In addition, the embodiments should be understood as illustrative but not restrictive to the scope of the disclosure, and the spirit and scope of the disclosure are defined only by the claims. For those skilled in the art, various changes and modifications to compositions and amounts in these embodiments are within the scope of the present disclosure, without departing from the spirit and scope of the disclosure.

(2) The present disclosure provides a method for preparing a magnetic adsorbent used for superconducting magnetic separation, comprising the following steps:

(3) preparing an iron-based gel by a ferric salt solution and an alkali solution, wherein, dropping the alkali solution slowly into the ferric salt solution and balancing the pH value between 4 to 7.5 under conditions of sufficient stirring, then continuing stirring for 5 to 30 min and standing for 60 min to 24 h to obtain the iron-based gel;

(4) loading the obtained iron-based gel on a surface of ferrite by reaction in situ.

(5) wherein the concentration range of ferric salt is 0.5 to 10 mmol/L and the concentration range of OH.sup.− in the alkali solution is 0.1 to 10 mol/L.

(6) The suitable ferric salt is at least one of ferric chloride, ferric sulfate, ferric nitrate, polyferric chloride, polyferric sulfate and polyferric nitrate.

(7) The suitable alkali solution is at least one of sodium hydroxide, potassium hydroxide and aqueous ammonia.

(8) Further, the iron-based gel is loaded on the ferrite surface using the following method:

(9) (1) adding polyacrylamide solution slowly into ferrite solution under conditions of sufficient stirring, in which the mass ratio of polyacrylamide to ferrite is 1:100 to 1:50000, and reacting for 30 to 120 min to obtain a ferrite suspension;

(10) (2) adding an iron-based gel suspension slowly into the ferrite suspension obtained in (1) under conditions of sufficient stirring, in which the mass ratio of the iron-based gel and ferrite is 1:10 to 1:500, and reacting for 60 to 240 min.

(11) The ferrite is at least one of manganous ferrite, copper ferrite, magnesium ferrite and ferroferric oxide.

Example 1

(12) Preparation of materials: manganous ferrite was selected as ferrite. Formulating ferric chloride solution and sodium hydroxide solution separately, in which the concentration of ferric chloride was 10 mmol/L and the concentration of OH.sup.−in the sodium hydroxide solution was 10 mol/L; under conditions of sufficient stirring, dropping the sodium hydroxide solution slowly into the ferric chloride solution until the pH value was balanced to 4.0; continuing stirring for 30 min and standing for 24 h to obtain an iron-based gel suspension.

(13) Preparation of magnetic adsorbent: under conditions of sufficient stirring, adding polyacrylamide solution slowly into a manganous ferrite suspension, in which the mass ratio of polyacrylamide to manganous ferrite was 1:50000, and reacting for 30 min; under conditions of sufficient stirring, adding the iron-based gel suspension slowly into the manganous ferrite suspension added with the polyacrylamide solution, in which the mass ratio of the iron-based gel to manganous ferrite was 1:500, and reacting for 60 min.

(14) Application to arsenic-containing water purification: arsenic polluted water was source water for drinking of natural groundwater, and the concentration of arsenic in water was 0.2 mg/L. The magnetic adsorbents were added into the arsenic polluted water in the addition amount of 100 mg/L and then sufficiently mixed; after 5 min of the mixing reaction, water added with the magnetic adsorbents was brought into a continuous superconducting magnetic separation system for solid-liquid separation, and the treated water was discharged when the outflow from the separation system met the drinking water sanitary standard.

Example 2

(15) Preparation of materials: copper ferrite was selected as ferrite. Formulating ferric nitrate solution and potassium hydroxide solution separately, in which the concentration of ferric nitrate was 0.5 mmol/L and the concentration of OH.sup.−in the potassium hydroxide solution was 0.1 mol/L; under conditions of sufficient stirring, dropping the potassium hydroxide solution slowly into the ferric nitrate solution until the pH value was balanced to 7.5; continuing stirring for 5 min, and standing for 60 min to obtain an iron-based gel suspension.

(16) Preparation of magnetic adsorbent: under conditions of sufficient stirring, adding polyacrylamide solution slowly into a copper ferrite suspension, in which the mass ratio of polyacrylamide to copper ferrite was 1:100 and reacting for 120 min; under conditions of sufficient stirring, adding the iron-based gel suspension slowly into the ferrite suspension added with the polyacrylamide solution in which the mass ratio of the iron-based gel to ferrite was 1:10, and reacting for 240 min.

(17) Application to arsenic-containing water purification: arsenic polluted water was industrial wastewater, and the concentration of arsenic in water was 20.0 mg/L. The magnetic adsorbents were added into the arsenic polluted water in the addition amount of 5 g/L and then sufficiently mixed; after 5 min of the mixing reaction, water added with the magnetic adsorbents was brought into a continuous superconducting magnetic separation system for solid-liquid separation, and the treated water was discharged when the outflow from the separation system met the industrial wastewater discharge standard.

Example 3

(18) Preparation of materials: magnesium ferrite was selected as ferrite. Formulating ferric sulfate solution and aqueous ammonia solution separately, in which the concentration of ferric sulfate was 6 mmol/L and the concentration of OH.sup.−in the aqueous ammonia solution was 3 mol/L; under conditions of sufficient stirring, dropping the aqueous ammonia solution slowly into the ferric sulfate solution until the pH value was balanced to 6; continuing stirring for 15 min, and standing for 10 h to obtain an iron-based gel suspension.

(19) Preparation of magnetic adsorbent: under conditions of sufficient stirring, adding polyacrylamide solution slowly into a magnesium ferrite suspension, in which the mass ratio of polyacrylamide to magnesium ferrite was 1:1000, and reacting for 60 min; under conditions of sufficient stirring, adding the iron-based gel suspension slowly into the ferrite suspension added with the polyacrylamide solution, in which the mass ratio of the iron-based gel to the ferrite was 1:50, and reacting for 120 min.

(20) Application to arsenic-containing water purification: arsenic polluted water was polluted river water, and the concentration of arsenic in water was 5.0 mg/L. The magnetic adsorbents were added into the arsenic polluted water in the addition amount of 500 mg/L and then sufficiently mixed; after 3 min of the mixing reaction, the water added with the magnetic adsorbents was brought into a continuous superconducting magnetic separation system for solid-liquid separation, and the treated water was discharged when the outflow from the separation system met the quality standard of surface water environment.

Example 4

(21) Preparation of materials: a mixture of ferroferric oxide and manganous ferrite at a mass ratio of 1:2 were used as ferrite. Formulating polyferric chloride solution and potassium hydroxide solution separately, in which the concentration of polyferric chloride was 3.5 mmol/L and the concentration of OH.sup.−in the potassium hydroxide solution was 6.5 mol/L; under conditions of sufficient stirring, dropping the potassium hydroxide solution slowly into the polyferric chloride solution until the pH value was balanced to 5.5; continuing stirring for 30 min, and standing for 5 h to obtain an iron-based gel suspension.

(22) Preparation of magnetic adsorbent: under conditions of sufficient stirring, adding polyacrylamide solution slowly into a copper ferrite suspension, in which the mass ratio of polyacrylamide to copper ferrite was 1:25000, and reacting for 90 min; under conditions of sufficient stirring, adding the iron-based gel suspension slowly into the ferrite suspension added with the polyacrylamide solution, in which the mass ratio of the iron-based gel to the ferrite was 1:300, and reacting for 180 min.

(23) Application to arsenic-containing water purification: arsenic polluted water was industrial wastewater, and the concentration of arsenic in the arsenic polluted water was 10.0 mg/L. The magnetic adsorbents were added into the arsenic polluted water in the addition amount of 1.5 g/L and then sufficiently mixed; after 5 min of the mixing reaction, the water added with the magnetic adsorbents was brought into a continuous superconducting magnetic separation system for solid-liquid separation, and the treated water was discharged when the outflow from the separation system met the industrial wastewater discharge standard.