Lignocellulosic materials have great potential to be valorized into new products. Flax by-products such as powder and short fibers are used in the present study to identify plausible potential applications for the products obtained from their hydrothermal treatment. The as-received industrial flax by-products are subjected to hydrothermal carbonization (HTC) in a wide range of severity, an operating parameter combining time and temperature. In this way, the yield and characteristics of the resulting HTC products: hydrochars, carbon quantum dots (CQDs) and organics such as 5-hydroxymethylfurfural (5-HMF) and furfural (FU), are determined. Likewise, pyrolysis of the hydrochars and the starting flax by-products at 900 °C is also carried out, leading to carbon materials with developed surface areas, higher than 950 m²/g, and CO₂ capture values of up to 4.8 mmol/g at 1 bar and 0 °C. In the overall process, severities above 4.9 were found to be optimal in terms of higher calorific value (around 27 MJ/kg) of the obtained hydrochars, production of organic products (0.22 and 0.06 g/L of 5-HMF and FU, respectively), photoluminescence quantum yield of the CQDs fraction (4.7%) and CO₂ capture (up to 4.8 mmol/g) by the hydrochar-derived carbons.

木质纤维素材料在新产品中具有巨大潜力。本研究中使用亚麻副产品（如粉末和短纤维）来确定从其水热处理获得的产品的合理潜在应用。收到的工业亚麻副产品经过水热碳化 (HTC) 的严重程度范围广泛，操作参数结合了时间和温度。通过这种方式，确定了所得 HTC 产品的产率和特性：水炭、碳量子点 (CQD) 和有机物，例如 5-羟甲基糠醛 (5-HMF) 和糠醛 (FU)。同样，水炭和起始亚麻副产品在 900 °C 下也进行热解，从而产生具有发达表面积的碳材料，高于 950 m ²/g 和 CO ₂在 1 bar 和 0 °C 下的捕获值高达 4.8 mmol/g。在整个过程中，发现 4.9 以上的严重性在获得的水炭的较高热值（约 27 MJ/kg）、有机产品的生产（分别为 0.22 和 0.06 g/L 的 5-HMF 和 FU）方面是最佳的)、CQDs 部分的光致发光量子产率 (4.7%) 和水炭衍生的碳捕获的 CO ₂ (高达 4.8 mmol/g)。