Porous carbon monoliths (PCMs) were prepared from waste corrugated cardboard box (WCCB) via slurrying in FeCl3 solution followed by molding and thermal treatment. The thermal process was analyzed by a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer. The evolution of physicochemical characteristics of PCMs was studied. The photothermal conversion and solar steam generation performances of the optimal sample (PCMFe/600) were evaluated. The adsorption properties of PCMFe/600 for methylene blue (MB) were investigated. Results showed that Fe3+ promoted the breaking of cellulose chains in WCCB, leading to the occurrence of pyrolysis of WCCB at lower temperatures and the reduction of activation energy by 76.63 kJ mol-1. Char yield raised because volatile radicals were captured by FeCl3-derived amorphous Fe(III) species, then involved in char formation. Amorphous Fe(III) continuously converted into Fe3O4 crystallites with carbonization temperature increasing from 400 to 700 °C, then α-Fe was formed at 800 °C via the carbothermal reduction of Fe3O4. FeCl3 was favorable to the formation of a developed microporous structure. Surface area significantly increased with carbonization temperature increasing from 400 to 600 °C due to the removal of volatiles. The etching of carbon by Fe3O4 above 700 °C also led to the increase of surface area. PCMFe/600 exhibited higher optical absorption than other samples due to its high graphite degree and porosity. It also had excellent photothermal performance; thus, solar steam yield was 1.46 times that of the pure water with the assistance of PCMFe/600. PCMFe/600 in floating state was effective in adsorption of MB from water. Besides, the adsorption behavior fitted Langmuir model with a monolayer adsorption capacity reached up to 70.9 mg g-1.

中文翻译：

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从废旧瓦楞纸板箱中轻松制备磁性多孔碳单块用于太阳能蒸汽的产生和吸附。

多孔碳单块 (PCM) 由废瓦楞纸板 (WCCB) 通过在 FeCl3 溶液中制浆，然后成型和热处理而制备。通过与傅里叶变换红外光谱仪耦合的热重分析仪分析热过程。研究了PCM的物理化学特性的演变。评估了最佳样品（PCMFe/600）的光热转换和太阳能蒸汽产生性能。研究了 PCMFe/600 对亚甲基蓝 (MB) 的吸附性能。结果表明，Fe3+促进了WCCB中纤维素链的断裂，导致WCCB在较低温度下发生热解，活化能降低76.63 kJ mol-1。由于挥发性自由基被 FeCl3 衍生的无定形 Fe(III) 物质捕获，炭产量提高，然后参与炭的形成。随着碳化温度从400℃升高到700℃，无定形Fe(III)不断转化为Fe3O4微晶，然后在800℃通过Fe3O4的碳热还原形成α-Fe。FeCl3有利于形成发达的微孔结构。由于挥发物的去除，表面积随着碳化温度从 400 到 600 °C 的增加而显着增加。Fe3O4 在 700 ℃以上对碳的蚀刻也导致表面积的增加。由于其高石墨度和孔隙率，PCMFe/600 表现出比其他样品更高的光吸收。它还具有优异的光热性能；因此，在 PCMFe/600 的帮助下，太阳能蒸汽产量是纯水的 1.46 倍。漂浮状态的 PCMFe/600 能有效吸附水中的 MB。