Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, PR China.
Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, PR China.
Sci Total Environ. 2019 Dec 1;694:133728. doi: 10.1016/j.scitotenv.2019.133728. Epub 2019 Aug 5.
To study the formation of biochar with high absorbability, experiments were carried out at different carbonization temperature (300, 400, 600, and 800 °C) and under different carbonization atmosphere (activating gases (steam and CO) and inert gas (N)) to prepare biochar. In this paper, the effects of the carbonization atmosphere on the biochar pore structure were studied, and the influence of the biochar pore structure on the adsorption-desorption behaviour of nutrients (NH-N, NO-N, P, and K) was investigated. Experimental results: (1) The activating gases (steam and CO) can catalytically crack activated carbon atoms and tar blocking the biochar pores at high temperatures (T > 600 °C), and the activating gas promotes the formation of microporous biochar (d < 2 nm). (2) Micropores with a pore diameter distribution of 0.6-2 nm in biochar have the strongest nutrients adsorption, and pores with a diameter below 0.6 nm cannot adsorb hydrated ions of nutrients. (3) Biochar prepared at 600 °C and CO atmosphere has the best adsorption effect on nutrients. The adsorption kinetic was well described by Pseudo-second-order model. (4) After 5 cycles of biochar, the adsorption of the nutrients is still >40% of the first adsorption. Biochar has relatively high reusability.
为了研究高吸附性生物炭的形成，在不同碳化温度（300、400、600 和 800°C）和不同碳化气氛（活化气体（蒸汽和 CO）和惰性气体（N））下进行了实验来制备生物炭。本文研究了碳化气氛对生物炭孔结构的影响，并探讨了生物炭孔结构对养分（NH-N、NO-N、P 和 K）吸附-解吸行为的影响。实验结果表明：（1）在高温（T>600°C）下，活化气体（蒸汽和 CO）可以催化裂解活性炭原子和焦油堵塞生物炭孔，活化气体促进微孔生物炭（d<2nm）的形成。（2）生物炭中孔径分布在 0.6-2nm 的微孔对养分具有最强的吸附能力，直径小于 0.6nm 的孔不能吸附养分的水合离子。（3）在 600°C 和 CO 气氛下制备的生物炭对养分的吸附效果最好，吸附动力学很好地符合伪二级模型。（4）经过 5 次生物炭循环后，养分的吸附率仍>40%，高于第一次吸附率。生物炭具有较高的可重复使用性。
