A biomass carbon composite material with high adsorption performance and its preparation method and application

Abstract

The present invention relates to the technical field of biochar adsorption materials, and specifically provides a biochar composite material with high adsorption performance, and a preparation method and application thereof. The method comprises: (1) mixing a biochar source with a 10-15wt% calcium chloride solution, adjusting the pH to 2-3; performing a hydrothermal reaction at 160-180°C; (2) after the hydrothermal reaction, drying the system, and calcining the dried material to obtain a biochar material; (3) performing a low-temperature plasma treatment on the biochar material for 3-5 minutes; (4) mixing the material obtained in step (3) with a 5-8wt% chitosan solution, and drying. The biochar composite material with high adsorption performance prepared by the method of the present invention has good adsorption capacity for a variety of heavy metals in urban sewage, and will not cause secondary pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of biochar adsorption materials, and more specifically to a biochar composite material with high adsorption performance and a preparation method and application thereof. Background Art

[0002] Urban sewage may contain a variety of heavy metals, among which the common heavy metals include: Lead (Pb): mainly comes from industrial wastewater, automobile exhaust, etc., which is harmful to human health and can cause nervous system damage and other health problems; Cadmium (Cd): commonly found in electronic waste, fertilizers, etc., which is harmful to human health and the environment, and will accumulate in the human body to cause a variety of diseases; Chromium (Cr): including hexavalent chromium and trivalent chromium, hexavalent chromium is harmful to the human body, and comes from industrial wastewater, leather processing wastewater, etc. If these heavy metals exceed the allowable concentration of the environment, they will have a serious impact on aquatic life and human health, so effective sewage treatment is needed; Nickel (Ni): mainly comes from industrial wastewater, fuel combustion, etc., excessive intake can cause skin allergies and other health problems.

[0003] Biochar is a renewable energy source. It is a solid carbon material made from biomass raw materials (such as wood, straw, fruit shells, etc.) through high-temperature carbonization. It has the characteristics of being porous, having a large specific surface area, and having strong adsorption properties. Therefore, it is expected to become a new adsorbent for removing heavy metal ions.

[0004] High-performance biochar usually refers to biochar that has been treated with a special process and has a high degree of carbonization and adsorption performance. The invention patent application with application publication number CN105836745A discloses a method for preparing a sycamore leaf carbon material, which specifically uses sycamore leaves to obtain a carbon material through hydrothermal carbonization, and then undergoes multiple steps of activation to prepare a carbon material with a honeycomb structure; the sycamore leaf carbon material has a good adsorption effect on hexavalent chromium, but the adsorption effect on other heavy metals in urban sewage, such as cadmium or chromium, is unknown to those skilled in the art. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a high-adsorption biomass charcoal composite material and its preparation method and application. The high-adsorption biomass charcoal composite material prepared by the method of the present invention has good adsorption capacity for various heavy metals in urban sewage and will not cause secondary pollution.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a biomass carbon composite material with high adsorption performance, comprising:

[0008] (1) Mix the biomass carbon source with 10-15wt% calcium chloride solution, adjust the pH to 2-3, and perform a hydrothermal reaction at 160-180°C;

[0009] (2) After the hydrothermal reaction is completed, the system is dried, and the dried material is calcined to obtain a biochar material;

[0010] (3) treating the biochar material with low-temperature plasma for 3 to 5 minutes;

[0011] (4) The material obtained in step (3) is mixed with 5-8 wt% chitosan solution and dried to obtain a biomass carbon composite material with high adsorption performance.

[0012] Preferably, step (1) further comprises: pre-treating the biomass carbon source; the pre-treatment comprises: washing and crushing; the crushed biomass carbon source is preferably sieved through an 80-mesh sieve; the biomass carbon source comprises one or more of fruit shells, straws, and wood chips; the straw comprises one of the carbonizable organic matter in crop straw, wood chips, branches, fallen leaves, sawdust, and urban garbage; the crop straw comprises one or more of corn straw, wheat straw, soybean straw, rice straw, sorghum straw, and cotton straw, preferably rice straw; the wood chips comprise miscellaneous wood sawdust.

[0013] In step (1) of the present invention, the solid-liquid ratio of the biomass carbon source to the calcium chloride solution is (0.5~2):10g / ml; the mixing of the biomass carbon source and the calcium chloride solution is preferably carried out under stirring conditions; the stirring speed is preferably 500~600rpm, and the time is 10~15min; the pH is preferably adjusted with an organic acid; the organic acid includes one or more of citric acid, acetic acid, and oxalic acid; after adjusting the pH, the system is preferably stirred for 0.5~1h; the time of the hydrothermal reaction is preferably 10~12h; after the reaction is completed, the system is preferably dried at 90~100°C.

[0014] In step (2) of the present invention, the calcination treatment specifically comprises: heating to 700-800°C at a rate of 5-10°C / min for calcination, and keeping the temperature for 1-2h; the calcination treatment is preferably carried out under an argon protective atmosphere.

[0015] In step (3) of the present invention, the low-temperature plasma treatment is carried out under an oxygen atmosphere at 100-200W; the oxygen pressure is 0.3-0.5mbar; preferably, the biochar material is placed on a lower plate of a low-temperature plasma generator for low-temperature plasma treatment.

[0016] In step (4) of the present invention, the material-to-liquid ratio of the material obtained in step (3) to the chitosan solution is (1-2):5 g / ml, preferably 1:5 g / ml; the mixing of the material obtained in step (3) and the chitosan solution is carried out under stirring for 1-1.5 hours; in the chitosan solution, the viscosity of chitosan is 200-400 mPa·s.

[0017] The present invention also provides a biomass carbon composite material with high adsorption performance obtained by the preparation method of the above-mentioned biomass carbon composite material with high adsorption performance.

[0018] The present invention also provides the use of the above-mentioned high-adsorption performance biomass carbon composite material in the preparation of heavy metal adsorption products.

[0019] Preferably, the mass ratio of the high adsorption performance biomass carbon composite material to the heavy metal is 1:(200-450), more preferably 0.02:5.41, 0.02:8.05 or 0.02:6.43.

[0020] Preferably, the concentration of the high adsorption performance biomass carbon composite material in the heavy metal adsorption product is 2 mg / ml; in the heavy metal product, the concentration of heavy metals is 500-1000 mg / ml.

[0021] Preferably, the heavy metal includes one or more of cadmium, lead and chromium; the heavy metal includes heavy metal ions, preferably Pb 2+ 、Cd 2+ Cr 6+ One or more of .

[0022] Preferably, the product comprises a heavy metal ion adsorbent.

[0023] Compared with the prior art, the method for preparing the high-absorption biomass carbon composite material of the present invention has low cost and simple process. The obtained material has good adsorption capacity for various heavy metals in urban sewage and will not cause secondary pollution. The examples of the present invention have confirmed that the use of 0.02g of the high-absorption biomass carbon composite material of the present invention can absorb Pb in 10ml of urban sewage. 2+ The content of Cr decreased from 541mg / ml to 2.3mg / ml. 6+ The content of Cd decreased from 805mg / ml to 4.2mg / ml. 2+ The content dropped from 643mg / ml to 2.4mg / ml. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] To further illustrate the present invention, the following examples are used to describe it in detail. The raw materials used in the following examples of the present invention are all commercially available products. The chitosan used in the examples of the present invention and the comparative examples was purchased from Shanghai Myril Biochemical Technology Co., Ltd., with a product number of M29342 and a viscosity of 200-400 mPa·s.

[0026] Example 1

[0027] The method for preparing the biomass carbon composite material with high adsorption performance of this embodiment comprises the following steps:

[0028] (a) Rice straw was used as the biomass carbon source. The rice straw was washed, dried, mechanically crushed, and passed through an 80-mesh sieve.

[0029] (b) Take 20 g of the rice straw powder obtained in step (a), add it to 200 ml of calcium chloride solution (10 wt%), stir it thoroughly at 500 rpm for 10 min, adjust the pH of the system to 2 with acetic acid, and stir it for 0.5 h.

[0030] (c) The system obtained in step (b) is poured into a hydrothermal reactor and heated at 160°C for 8 hours. After the reaction is completed, it is dried at 90°C. Under an argon protective atmosphere, the dried material is placed in a tubular furnace, heated to 700°C at a rate of 5°C / min for calcination, and kept warm for 2 hours to obtain a biochar material.

[0031] (d) The biochar material obtained in step (c) is placed on the lower plate of a low-temperature plasma generator and activated for 5 minutes at 150 W in an oxygen atmosphere; the pressure of the introduced oxygen is 0.5 mbar.

[0032] (e) 100 g of the material obtained in step (d) was soaked in 0.5 L of chitosan solution (5 wt%) and stirred thoroughly to mix. After 1 h, the solid and liquid were separated and the solid was dried at 80 °C for 3 h to obtain a biomass carbon composite material with high adsorption performance.

[0033] Comparative Example 1

[0034] The preparation method of the biomass carbon composite material in this comparative example is different from that in Example 1 only in that the calcium chloride solution is replaced with deionized water in this comparative example, and the remaining steps are carried out with reference to the method in Example 1.

[0035] Comparative Example 2

[0036] The preparation method of the biomass carbon composite material in this comparative example is different from that in Example 1 only in that the excitation activation time of the low-temperature plasma in step (d) is adjusted to 8 minutes, and the remaining steps are carried out according to the method in Example 1.

[0037] Comparative Example 3

[0038] The preparation method of the biomass carbon composite material in this comparative example is different from that in Example 1 only in that the 5 wt % chitosan solution in this comparative example is replaced by a 5 wt % sodium alginate solution, and the remaining steps are carried out with reference to the method in Example 1.

[0039] Example 2

[0040] The method for preparing the biomass carbon composite material with high adsorption performance of this embodiment comprises the following steps:

[0041] (a) Rice straw was used as the biomass carbon source. The rice straw was washed, dried, mechanically crushed, and passed through an 80-mesh sieve.

[0042] (b) Take 10 g of the rice straw powder obtained in step (a), add it to 200 ml of calcium chloride solution (15 wt%), stir it thoroughly at 500 rpm for 10 min, adjust the pH of the system to 3 with citric acid, and stir it for 0.5 h.

[0043] (c) The system obtained in step (b) is poured into a hydrothermal reactor and heated at 160°C for 8 hours. After the reaction is completed, it is dried at 90°C. Under an argon protective atmosphere, the dried material is placed in a tubular furnace, heated to 750°C at a rate of 10°C / min for calcination, and kept warm for 1 hour to obtain a biochar material.

[0044] (d) The biochar material obtained in step (c) is placed on the lower plate of a low-temperature plasma generator and activated for 5 minutes at 150 W in an oxygen atmosphere; the pressure of the introduced oxygen is 0.4 mbar.

[0045] (e) 100 g of the material obtained in step (d) was soaked in 0.5 L of chitosan solution (8 wt %) and stirred thoroughly to mix. After 1 h, the solid and liquid were separated and the solid was dried at 80 ° C for 3 h to obtain a biomass carbon composite material with high adsorption performance.

[0046] Example 3

[0047] The method for preparing the biomass carbon composite material with high adsorption performance of this embodiment comprises the following steps:

[0048] (a) Rice straw was used as the biomass carbon source. The rice straw was washed, dried, mechanically crushed, and passed through an 80-mesh sieve.

[0049] (b) Take 20 g of the rice straw powder obtained in step (a), add it to 200 ml of calcium chloride solution (10 wt%), stir it thoroughly at 500 rpm for 10 min, adjust the pH of the system to 3 with acetic acid, and stir it for 0.5 h.

[0050] (c) The system obtained in step (b) is poured into a hydrothermal reactor and heated at 160°C for 8 hours. After the reaction is completed, it is dried at 90°C. Under an argon protective atmosphere, the dried material is placed in a tubular furnace, heated to 800°C at a rate of 5°C / min for calcination, and kept warm for 1 hour to obtain a biochar material.

[0051] (d) The biochar material obtained in step (c) is placed on the lower plate of a low-temperature plasma generator and activated for 3 minutes at 200 W in an oxygen atmosphere; the pressure of the introduced oxygen is 0.3 mbar.

[0052] (e) 100 g of the material obtained in step (d) was soaked in 0.5 L of chitosan solution (5 wt%) and stirred thoroughly to mix. After 1 h, the solid and liquid were separated and the solid was dried at 80 °C for 3 h to obtain a biomass carbon composite material with high adsorption performance.

[0053] Test example

[0054] 10 ml of urban sewage was taken into a glass centrifuge tube, and 0.02 g of the material prepared in the embodiment and the comparative example was added. After mixing evenly, it was placed in a shaker at a speed of 150 rpm and a temperature of 25°C. After continuous shaking for 12 hours, it was taken out and allowed to settle for 12 hours. The solution was subjected to ICP-OES heavy metal element determination before and after treatment, and the results were shown in Table 1 below.

[0055] Table 1

[0056]

[0057] It can be seen from Table 1 that, compared with the comparative example, the high adsorption performance biomass carbon composite material prepared in the embodiment of the present invention has a better adsorption capacity for various heavy metal ions in urban sewage and will not cause secondary pollution.

[0058] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a biomass carbon composite material, characterized in that: include: (1) mixing a biomass carbon source with a 10-15wt% calcium chloride solution, adjusting the pH to 2-3, and performing a hydrothermal reaction at 160-180°C; the material-liquid ratio of the biomass carbon source to the calcium chloride solution is (0.5-2): 10g / mL; the biomass carbon source includes one or more of fruit shells, straw, and sawdust; (2) After the hydrothermal reaction is completed, the system is dried, and the dried material is calcined to obtain a biochar material; the calcination treatment specifically includes: heating to 700-800°C at a rate of 5-10°C / min, and calcining for 1-2 hours; (3) treating the biochar material with low-temperature plasma for 3 to 5 minutes; the low-temperature plasma treatment is performed at 100 to 200 W in an oxygen atmosphere; The pressure of the oxygen is 0.3-0.5 mbar; (4) The material obtained in step (3) was mixed with 5-8 wt % chitosan solution at a material-liquid ratio of (1-2): 5 g / mL, and dried to obtain a biomass carbon composite material.

2. The biomass carbon composite material obtained by the preparation method of the biomass carbon composite material according to claim 1.

3. The use of the biomass carbon composite material according to claim 2 in the preparation of a heavy metal adsorption product, characterized in that: The heavy metals include Pb 2+ 、Cd 2+ Cr 6+ One or more of .

4. The use according to claim 3, characterized in that: The mass ratio of the biomass carbon composite material to the heavy metal is 1:(200-450).

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