Abstract Magnetic biochars are implicated in graphene micro-crystallite formation, soil redox processes and highly adsorbent chars. This study investigates the mechanisms of bamboo charring – when impregnated with FeSO4·7H2O – at 250, 350, 450 and 550 °C, using thermal and static techniques. Impregnation resulted in the oxidation of Fe2+ to mixed Fe3+/Fe2+ (magnetite) oxide forms during pyrolysis. A reaction sequence was proposed in which Fe-sulphates were incorporated with an ammonia catalyst. Sulphur became ubiquitous in both inorganic and organic forms, and additional minerals also formed. Stable aromatics and separation of holo-cellulosic and degraded lignin volatilisation phases were catalysed, and carboxylation was inhibited. Concentrations of C fluctuated more substantially, before stabilising at high HTTs. Pyrolysis temperatures of 450 °C and above appear to maximise stable C concentrations.These observations indicated that this treatment may yield agriculturally engineered chars with enhanced redox potential, more neutral pH, and a range of nutrients.

中文翻译：

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富硫酸亚铁竹生物炭生产过程中无机反应的机制和后果

摘要 磁性生物炭与石墨烯微晶形成、土壤氧化还原过程和高吸附性炭有关。本研究使用热和静态技术研究了竹炭在 250、350、450 和 550 °C 下的炭化机制——当用 FeSO4·7H2O 浸渍时。浸渍导致 Fe2+ 在热解过程中氧化为混合的 Fe3+/Fe2+（磁铁矿）氧化物形式。提出了一种反应顺序，其中硫酸铁与氨催化剂结合。硫以无机和有机形式无处不在，并且还形成了其他矿物质。催化了稳定的芳烃和全纤维素和降解木质素挥发相的分离，并抑制了羧化。在稳定在高 HTT 之前，C 的浓度波动更大。