(2019) Journal of Colloid and Interface Science_CO₂ as a reaction medium for pyrolysis of lignin leading to magnetic cobalt-embedded biochar as an enhanced catalyst for Oxone activation

Yang M.-T., Tong W.-C., Lee J., Kwon E., Lin K.-Y.A.

(Academic Press Inc.) Journal of Colloid and Interface Science ISSN: 219797 Vol.545 Issue. Article No. DOI: 10.1016/j.jcis.2019.02.090

Carbonaceous materials have been proven as advantageous supports for anchoring cobalt (Co) nanoparticles (NPs) to formulate Co/carbon composite catalysts for Oxone activation in degrading pollutants in water. While Co/carbon composites represent attractive catalysts, most carbonaceous supports are usually sophisticatedly fabricated using fine chemicals and immobilization of Co on carbon supports requires complicated post-modifications. As biochar appears as a versatile but easily-accessible carbon, pyrolysis of Co/lignin can result in a promising Co/biochar (CoBC) catalyst for Oxone activation. Especially, when CO₂ is used to replace N₂ as a reaction medium for pyrolysis of Co/lignin, the syngas production from pyrolysis can be enhanced and a magnetic CoBC is also obtained. This CoBC appears as a micro-sized composite of Co nanoparticles (NPs) well-distributed and embedded within carbon matrices, and exhibits several advantageous properties, such as high porosity, large surface area and magnetism, making it an advantageous catalyst for activating Oxone in water. As decolorization of Amaranth (AMR) dye is employed as a model test, CoBC successfully activates Oxone to fully decolorize AMR within 60 min with a rate constant of 0.33 min ⁻¹ . CoBC also exhibits a much higher catalytic activity than CoBC prepared from pyrolysis in N₂ , and Co₃O₄ , revealing its promising advantages. The activation energy of AMR decolorization by CoBC-activated Oxone is 48 kJ/mol, which is also lower than those reported in other studies. CoBC can be also re-used to activate Oxone over multiple cycles. These findings validate that CoBC is certainly a promising heterogeneous catalyst, which can be simply prepared from pyrolysis of Co/lignin in CO₂ with concomitant enhanced syngas production. © 2019

This work is supported by the Ministry of Science and Technology (MOST), Taiwan , and financially supported by the “Innovation and Development Center of Sustainable Agriculture” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE), Taiwan . This work is supported by the Ministry of Science and Technology (MOST), Taiwan, and financially supported by the “Innovation and Development Center of Sustainable Agriculture” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE), Taiwan.