Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein, South Africa.
Department of Soil Science, Stellenbosch University, Matieland, South Africa.
Environ Technol. 2022 Feb;43(5):774-787. doi: 10.1080/09593330.2020.1804466. Epub 2020 Aug 11.
Biochar is known to be a highly adsorptive material, especially when the biochar is altered by activation to further increase its sorption ability. Little information, however, is available on the potential reversibility of both ammonium () and nitrate () sorption on the inherent biochar pH. The objective of our study was to characterise biochars made using different pyrolysis conditions from five various plant materials and rubber tyre, and to use them to investigate the biochar properties responsible for and adsorption and desorption. The rubber tyre, maize stover and sugarcane pith were the weakest adsorbing biochars (5.7-7.8 mg g) and best described by the Freundlich adsorption isotherm. The grape pip, grape skin and pine wood biochars had adsorption capacities in the range 8.3-9.4 mg g and best described by a linear adsorption isotherm at 100 mg L. The adsorption results were associated with physisorption which implies that they can act as slow release fertilisers if is bioavailable. The six biochars had adsorption capacities in the range 15.2-15.9 mg g and were well fitted to the linear adsorption isotherm at 100 mg L. All six biochars had a stronger removal affinity (82-89%) compared to (33-39%). Adsorbed nitrate was not desorbable (0.01-0.23%) compared to adsorbed which was 53-60% desorbable. The desorption result was possibly due to competing redox reactions or being too strongly adsorbed for extraction. Desorption of was associated with biochar net negative pH values and volatilisation of ammonia.
生物炭是一种高吸附性材料，特别是在经过活化处理以进一步提高其吸附能力后。然而，关于固有生物炭 pH 值对铵（）和硝酸盐（）吸附的潜在可逆性的信息很少。我们的研究目的是描述使用来自五种不同植物材料和橡胶轮胎的不同热解条件制成的生物炭，并利用它们来研究导致和吸附和解吸的生物炭特性。橡胶轮胎、玉米秸秆和甘蔗髓是吸附能力最弱的生物炭（5.7-7.8 mg g），最适合用 Freundlich 吸附等温线描述。葡萄皮、葡萄皮和松木生物炭的吸附能力在 8.3-9.4 mg g 范围内，在 100 mg L 时最好用线性吸附等温线描述。吸附结果与物理吸附有关，这意味着如果可以生物利用，它们可以作为缓释肥料。六种生物炭的吸附能力在 15.2-15.9 mg g 范围内，在 100 mg L 时很好地符合线性吸附等温线。与（33-39%）相比，所有六种生物炭对（82-89%）的去除亲和力更强。与可解吸的吸附相比，吸附的硝酸盐不可解吸（0.01-0.23%）。吸附的硝酸盐不可解吸（0.01-0.23%）。吸附的硝酸盐不可解吸（0.01-0.23%）。吸附的硝酸盐不可解吸（0.01-0.23%）。吸附的硝酸盐不可解吸（0.01-0.23%）。吸附的硝酸盐不可解吸（0.01-0.23%）。与生物炭净负 pH 值和氨挥发有关。
