Biochar, preparation method and applications thereof

Abstract

A biochar, its preparation method, and its applications are disclosed. The biochar preparation method includes an activation step and a pyrolysis step. The activation step involves activating biomass with an ionic compound to form an activated mixture. The pyrolysis step involves pyrolyzing the activated mixture at a pyrolysis temperature for a period of time to form biochar. This invention can produce high-quality biochar with high specific surface area and high porosity at relatively low temperatures. The yield of the biochar of this invention increases with increasing pyrolysis temperature. Biochar possesses excellent physicochemical properties, making it not only highly effective in wastewater purification and soil fertility enhancement, but also suitable as an electrode material for high-performance energy storage devices (such as supercapacitors and sodium-ion batteries).

Claims

1. A method for preparing biochar, comprising the following steps: an activation step in which a biomass is immersed in a solution at room temperature to form an activated mixture, wherein the solution contains an ionic compound, and the ionic compound is sodium chloride, ammonium sulfate, potassium nitrate or calcium chloride, the concentration of the ionic compound in the solution being in the range of 0.001M to 2.0M; and a pyrolysis step in which the activated mixture is pyrolyzed at an atmospheric temperature without adjusting the pH of the activated mixture to form biochar, wherein the pyrolysis temperature is in the range of 350°C to 950°C, and the yield of the biochar increases with increasing pyrolysis temperature.

2. The method for preparing biochar as described in claim 1, wherein the soaking time in the activation step is 24 hours and the pyrolysis time in the pyrolysis step is 8 hours.

3. The method for preparing biochar as claimed in claim 1, wherein before the pyrolysis step, the activated mixture is further subjected to a drying step and a dehydration step in sequence, and after the pyrolysis step to form the biochar, the method further includes an acid washing step for washing the biochar with an acidic solution.

4. The method for preparing biochar as described in claim 1, wherein the biomass is selected from a group consisting of plant waste, agricultural by-products, agricultural waste, industrial by-products, forestry by-products, food processing residues, aquaculture waste and natural organic resources.

5. The method for preparing biochar as described in claim 1, wherein the concentration of the ionic compound in the solution ranges from 0.01 M to 1.0 M.

6. A biochar prepared by a method for preparing biochar as described in any one of claims 1 to 5, wherein the biochar has a specific surface area of ​​200 m² / g to 800 m² / g and a total pore volume of 0.3 cm³ / g to 1.2 cm³ / g.

7. A composition for wastewater treatment comprising biochar as described in claim 6.

8. A composition for soil improvement comprising biochar as described in claim 6.

9. An electrode for an energy storage device comprising biochar as described in claim 6, wherein the energy storage device is a supercapacitor or a sodium-ion battery, wherein in the supercapacitor the biochar is composite with a hydroxide, and wherein in the sodium-ion battery the electrode is an anode comprising the biochar, a conductive agent and a binder.

10. A use of the biochar as described in claim 6 for manufacturing electrodes for supercapacitors, anodes for sodium-ion batteries, soil amendments, or wastewater purification.

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