posted on 2024-03-05, 20:12authored bySobia Kousar, Mengjiao Fan, Qingyang Li, Kanwal Javed, Qurshia Choudhry, Zahra Essa Khan, Félix Mérimé Bkangmo Kontchouo, Shu Zhang, Xun Hu
Fish scales (FS) are not only a kitchen waste but can
also serve
as a resource when used as a precursor for the production of activated
carbon. However, pore development in activated carbon derived from
the FS could be hindered by the excessive cracking of the thermally
unstable collagens and fats in FS. Herein, an approach of impregnating
FS with bio-oil, before being activated with K2C2O4 at 800 °C, was executed, aiming to increase the
activated carbon yield, tailor the porous structures of activated
carbon, and find another outlet for application of bio-oil. The results
confirmed that the formation of activated carbon was diminished due
to the extreme conversion of proteins/fats to gaseous products during
FS activation. Cross-interactions between organics in the bio-oil
for impregnation with proteins in FS led to a doubling of the yield
of activated carbon and also increased the carbon content in activated
carbon (from 46.2% in the control sample to 62.0%) due to the formation
of organics with higher resistance to conversion to gaseous products.
Besides, more developed pore structures (more mesopores: 22.3% versus
12.0%) were generated through bio-oil impregnation (1349.3 m2/g versus 1206.3 m2/g in the control sample). In-situ
IR characterization indicated the formation of pores via cracking
of aliphatic structures in FS. Bio-oil impregnation formed more aliphatic
structures and destroyed strong hydrogen bonds in FS, generating more
developed pore structures. Additionally, hydrothermal carbonization
(HTC) of FS led to substantial leaching of organics to the extent
of generation of almost no pores from activation of the resulting
hydrochar. The co-HTC of FS with bio-oil can induce the transfer of
organics present in bio-oil to FS, facilitating pore development.