Abstract:
Effective resource utilization is key to sustainable solid waste management. Co-pyrolysis
as a method provides the advantage of resource utilization in the form of char and enhanced
removal of a variety of pollutants through adsorption. In this study, an innovative hybrid
activated carbon (HAC), obtained via co-pyrolysis of oily sludge cake (OSC) and food
waste (FW) to effectively test its adsorption capacity for Pb(II) ions. The Biochar was
activated with ammonium hydroxide (NH4OH). Two Kinetic models (pseudo-first-order,
pseudo-second-order) and isotherm models (Langmuir, Freundlich, Temkin, Dubinin-
Radushkevich) were employed to analyze the adsorption process. The pseudo-second-
order kinetic model and Langmuir isotherm best represented the Pb(II) adsorption
behavior. The Langmuir isotherm indicated a maximum Pb(II) adsorption capacity of
362.98 mg g-1
. When experimented for the effect of competing cations (Ca2+, Mg2+, Na+,
K+) on Pb(II) removal, the presence of Mg2+ resulted in the maximum reduction of Pb(II)
(removal efficiency, 7.52%). The synthesized HAC possessed a high surface area of 786.21
m2 g
-1
. Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) analyses revealed
the formation of new mineral precipitates (hydrocerussite, Pb3(CO3)2(OH)2) and cerussite
(PbCO3) during Pb(II) adsorption, indicating that mineral precipitation and ion exchange
are the dominant mechanisms. Notably, the prepared HAC demonstrated promising
capabilities for simultaneously removing multiple heavy metals including Pb(II), Cd(II),
Zn(II), and Ni(II). Furthermore, the HAC exhibited excellent reusability, maintaining high
Pb(II) removal capacity even after four regeneration cycles (90.5% removal). This
indicates HAC’s potential for practical water and wastewater treatment applications.
