Heat-treated biochar impregnated with zero-valent iron nanoparticles for organic contaminants removal from aqueous phase: Material characterizations and kinetic studies

Abstract

Biochar (BC) is an inexpensive and widely available carbon-based material with a variety of applications. Zero valent iron nanoparticles (nZVI), on the other hand, are highly reactive species. However, agglomeration and difficulty of separation from the treated media are the major reported drawbacks associated with nZVI application for water treatment. In this study, BC was modified by a simple heat-treatment, producing hydrophilic heat-treated biochar (HBC) with enhanced absorptive features, and was impregnated with nZVI, producing BC/nZVI composite for efficient organic contaminant removal. Synthesis conditions of BC/nZVI composite were optimized by evaluating p-nitrosodimethylaniline (pNDA) bleaching efficiency of various BC/nZVI samples synthesized under different conditions of pH, ultrasonication amplitude, and iron concentration. Variously-synthesized HBCs were then used to synthesize HBC/nZVI composites, and were characterized for surface morphology, surface chemistry, and elemental composition. The best-performing HBC/nZVI for pNDA bleaching was then used for trichloroethylene (TCE) removal from water. Using HBC/nZVI or BC/nZVI composites, the pseudo-second order model fit indicated a chemisorption mechanism for organic contaminants removal. Using 250&#8201

mg&#8201

L&#8722

1 of the best-performing HBC/nZVI, an 88% TCE reduction (initial concentration of 40&#8201

μg&#8201

1) was achieved after 20&#8201

min at pH&#8201

=&#8201

3.0, with a rate of 3.318&#8201

g&#8201

mg&#8722

1&#8201

min&#8722

1.