A saline-alkali soil remediation system

Abstract

A saline-alkali soil remediation system. The prepared sodium alginate-magnetic biochar can effectively leach out calcium and sodium ions in the saline-alkali soil, and can meet the remediation use requirements of the saline-alkali soil. In addition, the influence of the mass ratio of sodium alginate to magnetic biochar in the sodium alginate-magnetic biochar on the performance is taught, and in actual use, the mass ratio of sodium alginate to magnetic biochar should be controlled to 2:10-6:10.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of saline-alkali soil remediation, and particularly relates to a saline-alkali soil remediation system. BACKGROUND

[0002] Saline-alkali soil is a kind of soil with excessive water-soluble salt content, which has a complete ecological system and can cause adverse effects on the utilization potential of land resources. Excessive salinity can adversely affect the physical and chemical properties of soil. The domestic saline-alkali soil improvement methods can be roughly divided into physical improvement, chemical improvement and biological improvement. In the prior art, some scholars have prepared a humic acid-magnetic biochar material, which can effectively leach out sodium ions in high-sodium saline-alkali soil, but the removal effect of calcium ions is not satisfactory, so it is difficult to be applied to the saline-alkali soil remediation system with excessive calcium and sodium. SUMMARY

[0003] In view of the problems in the prior art, the present application aims to provide a saline-alkali soil remediation system which can effectively remove calcium and sodium metals in soil.

[0004] A saline-alkali soil remediation system comprises the steps of using sodium alginate-magnetic biochar to remediate saline-alkali soil, and the preparation method of the sodium alginate-magnetic biochar comprises the following steps:

[0005] The crushed rice straw powder is placed in an oven at 100-110 DEG C, dried for 24-30 h, and sieved through a 60-100 mesh sieve; it is placed in a quartz boat and pyrolyzed in a muffle furnace under nitrogen atmosphere for 3-5 h, and the heating rate during pyrolysis is 10-15 DEG C / min to obtain rice straw biochar;

[0006] 7.3-8.5 g of FeSO4·7H2O and 4.3-5.2 g of FeCl3 are weighed and dissolved in 200-500 mL of deionized water, 8-15 g of rice straw biochar is added to the above solution and magnetically stirred for 20-50 min; the pH value is adjusted to 10-11 at room temperature with NaOH, and after sufficient stirring, the precipitate and the solution are separated by suction filtration, and the precipitate is washed repeatedly with deionized water until the filtrate is clear and the pH is about 7, and finally the black precipitate is freeze-dried for 30-36 h, and then ground through a 60-100 mesh sieve to obtain magnetic biochar;

[0007] Sodium alginate-magnetic biochar was obtained by taking 2-6 g of sodium alginate and dissolving it in deionized water, stirring it with a magnetic stirrer for 20-30 min, adjusting the pH to neutral with 1-2.5 mol / L HCl, adding 10-12 g of magnetic biochar and stirring it at a rotation speed of 300-500 rpm for 24-30 h, standing for 18-24 h, then repeatedly washing the precipitate with deionized water until the filtrate was clear and neutral, and finally freeze-drying the precipitate for 24-30 h, taking it out, grinding it and passing it through a 60-100 mesh sieve.

[0008] Preferably, the pyrolysis time is 3 h.

[0009] Preferably, the sodium alginate is 4.2 g.

[0010] Preferably, the rotation speed is 300 rpm.

[0011] Preferably, the FeCl3 is 4.3 g.

[0012] Preferably, the FeSO4·7H2O is 7.3 g.

[0013] The sodium alginate-magnetic biochar prepared by the present application can effectively leach out calcium and sodium ions in saline-alkali soil, and can meet the repair use requirements of saline-alkali soil with excessive calcium and sodium ions. In addition, the amount ratio of sodium alginate to magnetic biochar in the sodium alginate-magnetic biochar has a great influence on its performance, and in actual use, the mass ratio of sodium alginate to magnetic biochar should be controlled at 2:10-6:10. DETAILED DESCRIPTION

[0014] The technical effects of the present application will be verified by specific examples below, but the embodiments of the present application are not limited thereto.

[0015] The preparation method of the magnetic biochar in the present application refers to the prior art (Influence mechanism of humic acid-magnetic biochar on repair and plant growth characteristics of slightly saline-alkali soil).

[0016] Example 1

[0017] The crushed rice straw powder was placed in an oven at 110℃, dried for 24 h, and sieved through a 60 mesh sieve; it was then placed in a quartz boat and pyrolyzed in a muffle furnace under a nitrogen atmosphere for 3 h at a heating rate of 10℃ / min, obtaining rice straw biochar.

[0018] Take 7.3 g of FeS04·7H20 and 4.3 g of FeCl3, dissolve in 200 mL of deionized water, add 8 g of rice straw biochar to the above solution and stir magnetically for 20 min; adjust the pH to 10.8 with NaOH at room temperature, stir thoroughly and stand for 0.5 h, separate the precipitate and the solution by suction filtration, and wash the precipitate with deionized water repeatedly until the filtrate is clear and the pH is 7, and finally freeze-dry the black precipitate for 30 h, grind it through a 60 mesh sieve after taking it out, and obtain the magnetic biochar;

[0019] Take 2 g of sodium alginate and dissolve it in deionized water, stir magnetically for 20 min, adjust the pH to neutral with 1 mol / L HCl, add 10 g of magnetic biochar and stir at a speed of 300 rpm for 24 h, stand for 18 h, then wash the precipitate with deionized water repeatedly until the filtrate is clear and neutral, and finally freeze-dry the precipitate for 24 h, grind it and pass it through a 60 mesh sieve after taking it out, and obtain sodium alginate-magnetic biochar.

[0020] Example 2

[0021] Put the crushed rice straw powder into an oven at 110°C, dry for 24 h, and sieve through a 60 mesh sieve; put it into a quartz boat and pyrolyze in a muffle furnace under a nitrogen atmosphere for 3 h, with a heating rate of 10°C / min during pyrolysis, to obtain rice straw biochar;

[0022] Take 7.3 g of FeS04·7H20 and 4.3 g of FeCl3, dissolve in 200 mL of deionized water, add 8 g of rice straw biochar to the above solution and stir magnetically for 20 min; adjust the pH to 10.8 with NaOH at room temperature, stir thoroughly and stand for 0.5 h, separate the precipitate and the solution by suction filtration, and wash the precipitate with deionized water repeatedly until the filtrate is clear and the pH is 7, and finally freeze-dry the black precipitate for 30 h, grind it through a 60 mesh sieve after taking it out, and obtain the magnetic biochar;

[0023] Take 3 g of sodium alginate and dissolve it in deionized water, stir magnetically for 20 min, adjust the pH to neutral with 1 mol / L HCl, add 10 g of magnetic biochar and stir at a speed of 300 rpm for 24 h, stand for 18 h, then wash the precipitate with deionized water repeatedly until the filtrate is clear and neutral, and finally freeze-dry the precipitate for 24 h, grind it and pass it through a 60 mesh sieve after taking it out, and obtain sodium alginate-magnetic biochar.

[0024] Example 3

[0025] Put the crushed rice straw powder into an oven at 110°C, dry for 24 h, and sieve through a 60 mesh sieve; put it into a quartz boat and pyrolyze in a muffle furnace under a nitrogen atmosphere for 3 h, with a heating rate of 10°C / min during pyrolysis, to obtain rice straw biochar;

[0026] Take 7.3 g of FeSO4·7H2O and 4.3 g of FeCl3, dissolve in 200 mL of deionized water, add 8 g of rice straw biochar to the above solution and stir magnetically for 20 min; adjust the pH to 10.8 with NaOH at room temperature, stir thoroughly and stand for 0.5 h, separate the precipitate and the solution by suction filtration, and wash the precipitate repeatedly with deionized water until the filtrate is clear and the pH is 7, and finally freeze-dry the black precipitate for 30 h, grind it through a 60 mesh sieve after taking it out, and obtain the magnetic biochar;

[0027] Take 4.2 g of sodium alginate and dissolve it in deionized water, stir magnetically for 20 min, and adjust the pH to neutral with 1 mol / L HCl, add 10 g of magnetic biochar and stir at a speed of 300 rpm for 24 h, stand for 18 h, then wash the precipitate repeatedly with deionized water until the filtrate is clear and neutral, and finally freeze-dry the precipitate for 24 h, grind it and pass it through a 60 mesh sieve after taking it out, and obtain sodium alginate-magnetic biochar.

[0028] Example 4

[0029] Put the crushed rice straw powder into an oven at 110°C, dry for 24 h, and sieve through a 60 mesh sieve; put it into a quartz boat and pyrolyze in a muffle furnace under a nitrogen atmosphere for 3 h, with a heating rate of 10°C / min during pyrolysis, to obtain rice straw biochar;

[0030] Take 7.3 g of FeSO4·7H2O and 4.3 g of FeCl3, dissolve in 200 mL of deionized water, add 8 g of rice straw biochar to the above solution and stir magnetically for 20 min; adjust the pH to 10.8 with NaOH at room temperature, stir thoroughly and stand for 0.5 h, separate the precipitate and the solution by suction filtration, and wash the precipitate repeatedly with deionized water until the filtrate is clear and the pH is 7, and finally freeze-dry the black precipitate for 30 h, grind it through a 60 mesh sieve after taking it out, and obtain the magnetic biochar;

[0031] Take 5 g of sodium alginate and dissolve it in deionized water, stir magnetically for 20 min, and adjust the pH to neutral with 1 mol / L HCl, add 10 g of magnetic biochar and stir at a speed of 300 rpm for 24 h, stand for 18 h, then wash the precipitate repeatedly with deionized water until the filtrate is clear and neutral, and finally freeze-dry the precipitate for 24 h, grind it and pass it through a 60 mesh sieve after taking it out, and obtain sodium alginate-magnetic biochar.

[0032] Example 5

[0033] The crushed rice straw powder was placed in an oven at 110°C, dried for 24h, and sieved through a 60 mesh sieve; placed in a quartz boat and pyrolyzed in a muffle furnace under a nitrogen atmosphere for 3h, with a heating rate of 10°C / min, to obtain rice straw biochar;

[0034] 7.3g of FeS04-7H20 and 4.3g of FeCl3 were weighed and dissolved in 200mL of deionized water, 8g of rice straw biochar was added to the above solution and magnetically stirred for 20min; the pH was adjusted to 10.8 with NaOH at room temperature, after stirring thoroughly, it was left to stand for 0.5h, the precipitate and the solution were separated by suction filtration, and the precipitate was washed repeatedly with deionized water until the filtrate was clear and the pH was 7, finally the black precipitate was freeze-dried for 30h, ground and sieved through a 60 mesh sieve, to obtain magnetic biochar;

[0035] 6g of sodium alginate was dissolved in deionized water, magnetically stirred for 20min, and the pH was adjusted to neutral with 1mol / L HCl, 10g of magnetic biochar was added and stirred at a speed of 300rpm for 24h, left to stand for 18h, then the precipitate was washed repeatedly with deionized water until the filtrate was clear and neutral, finally the precipitate was freeze-dried for 24h, ground and sieved through a 60 mesh sieve, to obtain sodium alginate-magnetic biochar.

[0036] Comparative Example 1

[0037] The crushed rice straw powder was placed in an oven at 110°C, dried for 24h, and sieved through a 60 mesh sieve; placed in a quartz boat and pyrolyzed in a muffle furnace under a nitrogen atmosphere for 3h, with a heating rate of 10°C / min, to obtain rice straw biochar;

[0038] 7.3g of FeS04-7H20 and 4.3g of FeCl3 were weighed and dissolved in 200mL of deionized water, 8g of rice straw biochar was added to the above solution and magnetically stirred for 20min; the pH was adjusted to 10.8 with NaOH at room temperature, after stirring thoroughly, it was left to stand for 0.5h, the precipitate and the solution were separated by suction filtration, and the precipitate was washed repeatedly with deionized water until the filtrate was clear and the pH was 7, finally the black precipitate was freeze-dried for 30h, ground and sieved through a 60 mesh sieve, to obtain magnetic biochar;

[0039] 0.5g of sodium alginate was dissolved in deionized water, magnetically stirred for 20min, and the pH was adjusted to neutral with 1mol / L HCl, 10g of magnetic biochar was added and stirred at a speed of 300rpm for 24h, left to stand for 18h, then the precipitate was washed repeatedly with deionized water until the filtrate was clear and neutral, finally the precipitate was freeze-dried for 24h, ground and sieved through a 60 mesh sieve, to obtain sodium alginate-magnetic biochar.

[0040] Comparative Example 2

[0041] The pulverized rice straw powder was placed in an oven at 110℃, dried for 24h, and sieved through a 60-mesh sieve; it was then placed in a quartz boat and pyrolyzed in a muffle furnace under a nitrogen atmosphere for 3h, with a heating rate of 10℃ / min during pyrolysis, to obtain rice straw biochar;

[0042] 7.3g of FeSO4·7H2O and 4.3g of FeCl3 were weighed out and dissolved in 200mL of deionized water, and 8g of rice straw biochar was added to the solution and magnetically stirred for 20min; the pH was adjusted to 10.8 at room temperature using NaOH, and after thorough stirring, the mixture was allowed to stand for 0.5h; the precipitate and the solution were separated by suction filtration, and the precipitate was repeatedly washed with deionized water until the filtrate was clear and the pH was 7; finally, the black precipitate was freeze-dried for 30h, ground through a 60-mesh sieve, and magnetically stirred for 20min to obtain magnetic biochar;

[0043] 10g of sodium alginate was dissolved in deionized water, and after magnetic stirring for 20min, the pH was adjusted to neutral using 1mol / L HCl; 10g of magnetic biochar was added and stirred at a speed of 300rpm for 24h, and then allowed to stand for 18h; the precipitate was repeatedly washed with deionized water until the filtrate was clear and neutral; finally, the precipitate was freeze-dried for 24h, ground, and sieved through a 60-mesh sieve to obtain sodium alginate-magnetic biochar.

[0044] In the following, the performance of the sodium alginate-magnetic biochar (addition amount 1.3%) in Examples 1-5 and Comparative Examples 1-2 was evaluated by leaching experiments, and the experimental method can refer to the prior art mentioned above; the saline-alkali soil selected for the experiment was a calcium-sodium-exceeding type saline-alkali soil artificially prepared, and the content of Na and Ca in the soil was both 18mg / kg. To ensure the comparability of the experiment, 5 parallel experiments were set up for each group, and the average value was taken; the sodium alginate-magnetic biochar was different in each group of experiments, and the other experimental conditions were exactly the same; the final measurement was the concentration of sodium and calcium ions in the soil leaching solution when the cumulative infiltration amount was 500mL. The test results are shown in Table 1.

[0045] Table 1

[0046] No. Sodium ion concentration / ppm Calcium ion concentration / ppm Example 1 627 479 Example 2 692 506 Example 3 714 570 Example 4 681 533 Example 5 653 527 Comparative Example 1 651 315 Comparative Example 2 417 549

[0047] As can be seen from Table 1, the sodium alginate-magnetic biochar prepared by the present application can effectively leach out the calcium and sodium ions in the saline-alkali soil, and can meet the use requirements for the repair of such saline-alkali soil. In addition, the amount ratio of sodium alginate to magnetic biochar in the sodium alginate-magnetic biochar has a great influence on its performance, and in actual use, the mass ratio of sodium alginate to magnetic biochar should be controlled at 2:10 to 6:10.

[0048] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A saline-alkali land remediation system, characterized in that: The saline-alkali land restoration system includes using sodium alginate-magnetic biochar to repair the saline-alkali land, and the preparation method of the sodium alginate-magnetic biochar includes the following steps: The crushed rice straw powder was placed in an oven at 100-110°C, dried for 24-30 hours, and then sieved through a 60-100 mesh sieve; the powder was placed in a quartz boat and pyrolyzed in a muffle furnace under a nitrogen atmosphere for 3-5 hours at a heating rate of 10-15°C / min to obtain rice straw biochar; Weigh 7.3-8.5g FeSO4·7H2O and 4.3-5.2g FeCl3, dissolve in 200-500mL deionized water, add 8-15g rice straw biochar to the above solution and stir magnetically for 20-50min; adjust the pH value to 10-11 with NaOH at room temperature, stir thoroughly and let stand for 0.5-2h, separate the precipitate and solution by suction filtration, and repeatedly wash the precipitate with deionized water until the filtrate is clear and the pH is 7. Finally, freeze-dry the black precipitate for 30-36h, remove it and grind it through a 60-100 mesh sieve to obtain magnetic biochar; 2-6 g of sodium alginate was dissolved in deionized water, magnetically stirred for 20-30 min, and then the pH was adjusted to neutral with 1-2.5 mol / L HCl. 10-12 g of magnetic biochar was added and stirred at 300-500 rpm for 24-30 h. The mixture was allowed to stand for 18-24 h. The precipitate was then repeatedly washed with deionized water until the filtrate was clear and neutral. Finally, the precipitate was freeze-dried for 24-30 h, taken out, ground, and passed through a 60-100 mesh sieve to obtain sodium alginate-magnetic biochar. The mass ratio of sodium alginate to magnetic biochar was controlled at 2:10 to 6:

10.

2. A saline-alkali land remediation system according to claim 1, characterized in that: The pyrolysis time is 3 hours.

3. A saline-alkali land remediation system according to claim 1, characterized in that: The amount of the sodium alginate is 4.2 g.

4. A saline-alkali land remediation system according to claim 1, characterized in that: The rotation speed is 300 rpm.

5. A saline-alkali land remediation system according to claim 1, characterized in that: The FeCl3 is 4.3g.

6. A saline-alkali land remediation system according to claim 1, characterized in that: The amount of FeSO4·7H2O is 7.3 g.