Pyrolysis temperature is one of the main parameters affecting the properties of biochar and the composition of bio-oil during the pyrolysis of aquatic biomass such as seaweed. In this study, the evolution of the functional groups of biochar during seaweed pyrolysis was characterized with in situ diffuse reflectance infrared Fourier transform spectroscopy. The results showed that restructuring of the biochar was more pronounced at temperatures ranging from 230 to 290 °C, where the decomposition and pyrolysis of glucose crystals, polysaccharides and long-chain aliphatic compounds dominated. Fusion of the aromatic rings started and reached the equivalent of six fused rings at 500 °C and 12 fused benzene rings at 800 °C. Varying the pyrolysis temperature remarkably affected the distribution/transformation of the heteroatom in biochar and in the bio-oil formed. A large proportion of nitrogen in the original protein formed in seaweed was retained in the biochar, even at 800 °C. The sulfur species in the original sulfate polysaccharide form was transformed initially to Mg₂K₂(SO₄)₃ and then to MgO and CaS crystals. The oxygen content in the seaweed-derived biochar was rather high, as a significant portion of carbon was transferred into the tar fraction due to the aliphatic nature of seaweed.

热解温度是影响海藻等水生生物质热解过程中生物炭特性和生物油成分的主要参数之一。在这项研究中，利用原位漫反射红外傅里叶变换光谱对海藻热解过程中生物炭功能基团的演化进行了表征。结果表明，生物炭的重组在230至290°C的温度下更为明显，其中葡萄糖晶体，多糖和长链脂族化合物的分解和热解占主导地位。开始芳香环的融合，并在500°C时达到6个稠合环，在800°C时达到12个稠合苯环。改变热解温度显着影响了杂原子在生物炭和形成的生物油中的分布/转化。即使在800°C时，海藻中形成的原始蛋白质中的大部分氮也保留在生物炭中。最初硫酸盐多糖形式的硫物种最初转化为Mg₂ K ₂（SO ₄）₃，然后生成MgO和CaS晶体。由于海藻的脂肪族性质，很大一部分碳转移到焦油馏分中，因此海藻衍生的生物炭中的氧含量很高。