Liu Wenjian, Fan Mengjiao, Sun Kai, Cheng Xiao, Wu Fei, Zhang Shu, Hu Xun
School of Material Science and Engineering, University of Jinan, Jinan 250022, PR China.
Joint International Research Laboratory of Biomass Energy and Materials, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, PR China.
Sci Total Environ. 2025 May 1;975:179302. doi: 10.1016/j.scitotenv.2025.179302. Epub 2025 Apr 5.
FeCl is a Lewis acid catalyzing condensation reaction, which might be beneficial for enhancing mass yield of activated carbon (AC) if used as a co-activator. Herein, this was verified by conducting activation of willow with various activators (ZnCl, KCO, HPO) in the presence/absence of FeCl. The results indicated that FeCl competed with acid-catalyzed reactions induced by ZnCl or HPO, interfering aromatization and diminishing AC yields (from 40.8 % to 37.0 % with ZnCl). In the activation with KCO + FeCl, In-situ IR measurement showed that FeCl catalyzed polymerization reactions, but polymeric products were not stable and were further cracked with KCO, reducing AC yield drastically from 27.6 % to 7.1 %. The co-presence of FeCl in the activation reduced overall specific surface area (1201.6 versus 1127.2 m g for KCO) by merging of micropores to form a higher percentage of mesopores (i.e. 2.0 % to 17.1 % for KCO, and 9.2 % to 41.4 % for HPO). This pore restructuring significantly enhanced tetracycline adsorption (99.9 % removal for AC- KCO + FeCl versus 61.1 % for AC-KCO alone), while compromising phenol adsorption (48.7 % versus 96.1 %) due to reduced micropore availability. The reduced specific surface area was also attributed to the retention of inorganics by solid phase reactions between FeCl and KCO or HPO. Additionally, the presence of FeCl resulted in more fragmented surface of ACs generated from all activators.
氯化铁是一种催化缩合反应的路易斯酸，如果用作共活化剂，可能有利于提高活性炭（AC）的质量产率。在此，通过在有无氯化铁的情况下用各种活化剂（氯化锌、碳酸钾、磷酸）对柳树进行活化来验证这一点。结果表明，氯化铁与由氯化锌或磷酸引发的酸催化反应竞争，干扰芳构化并降低活性炭产率（用氯化锌时从40.8%降至37.0%）。在用碳酸钾 + 氯化铁进行活化时，原位红外测量表明氯化铁催化聚合反应，但聚合物产物不稳定，会被碳酸钾进一步裂解，使活性炭产率从27.6%急剧降至7.1%。活化过程中氯化铁的共存通过微孔合并形成更高比例的中孔，降低了总体比表面积（碳酸钾为1201.6对1127.2 m²/g，磷酸为9.2%至41.4%）。这种孔结构重组显著增强了四环素吸附（AC - 碳酸钾 + 氯化铁去除率为99.9%，而单独的AC - 碳酸钾为61.1%），但由于微孔可用性降低，损害了苯酚吸附（分别为48.7%对96.1%）。比表面积降低还归因于氯化铁与碳酸钾或磷酸之间的固相反应导致无机物的保留。此外，氯化铁的存在导致所有活化剂产生的活性炭表面更加破碎。
