Abstract:
Para nitroaniline (PNA) and para nitrophenol (PNP), used as pharmaceutical
precursors, are highly carcinogenic and mutagenic priority pollutants. Nano zero-valent iron (nZVI) has garnered much recent attention as a remediation tool, owing
to its advanced oxidation and adsorption capabilities. However, bare nZVI has
inherent issues of agglomeration and passivation which can be mitigated using a
support material like biochar (BC) known for its cost-effectiveness and eco-friendliness. Carbothermal reduction is a popular, relatively non-toxic approach for
nZVI synthesis, forming highly stable nZVI. Allowing carbothermal reduction of iron
on BC creates a surface-deposited material while allowing simultaneous pyrolysis
and reduction of a mixture of iron and carbonaceous material to form an nZVI-embedded BC. There have been no previous studies done on organic contaminant
removal by nZVI-embedded BC, nor have there been a comparative study between
the two carbothermally synthesized materials. A comprehensive batch sorption study
was carried out including pH, kinetic, isotherm, and regeneration experiments. Data
indicates that the surface-deposited material shows higher adsorption capability while
the embedded material exhibits superior regeneration ability. Thermodynamic data
validate the spontaneity and feasibility across different temperatures. This study
highlights the efficiency of BC-based nZVI as a potent tool for PNA and PNP
remediation in aqueous systems.
