Solidification and Stabilization of Spent Pine cone Biochar using Chemically Bonded Phosphate Cement
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Date
2023
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Abstract
Spent biochar is produced after adsorption of heavy metal
which is hazardous by nature. A suitable disposal technique is required
to prevent the leaching of heavy metals from spent biochar into the
environment. This study highlights the solidification and stabilization
(S/S) of copper loaded spent pine-cone biochar by chemically bonded
phosphate cement (CBPC). The response surface methodology (RSM) was
used to conduct S/S experiments in order to evaluate the compressive
strength of CBPC products. The CBPC samples were prepared by varying
biochar content (5-50 wt. %); W:S (0.15-0.3) and curing time(3-28d).
Results illustrated that CBPC products containing biochar had higher
compressive strength upto 12.8 MPa in comparison to CBPC without
biochar i.e., upto 10.8 MPa. XRD and SEM analysis confirmed the
presence of K-struvite (MgKPO4.6H2O), copper containing phases (Ca Cu-Si), copper phosphate precipitates (Cu3(PO4)2) and filling of pore
spaces by spent biochar. Highest compressive strength of 12.8 MPa was
obtained at an optimized biochar content of 25%, W:S of 0.18 and curing
time of 28 d. The evaluation of leaching potential by TCLP illustrated that
stabilization of Cu (II) upto 99.9% was achieved in CBPC product. The risk
assessment study revealed that there is no significant danger due to leaching
of heavy metals from final CBPC product indicating that it can be readily
disposed in the hazardous landfill sites.