Engineering of Activated Biochar Derived from Pine Needle Waste Biomass as Ozonation Catalyst in Water

Abstract

Valorization of biomass wastes into carbon-based catalysts for water treatment is a clear paradigm of sustainability.Herein, we investigate an unprecedented transformation of pine needle waste biomass into activated biochars (PNCs) as ozonation catalysts for aqueous oxalic acid degradation. The physico-chemical and textural properties of PNCs are tailored by combining pyrolysis temperatures up to 1200 °C and the use or not of KOH or K2CO3 as activating agents. The physico-chemical and structural properties of these carbocatalysts are correlated with their catalytic activities. The PNC catalyst pyrolized at 1200 °C for 4 h using K2CO3 (PNC1200-4K2CO3) provides a complete pollutant degradation after 150 min, while PNC catalyst pyrolized at 1200 °C for 4 h without activation requires 300 min. PNC1200-4K2CO3 performance compares favorably with previous reports. The superior catalytic activity of this reusable catalyst is attributed to its highest population of π-extended aromatic domains as active sites together with high porosity. The catalytic formation of 1O2, HO. and HOO. radicals are supported by electron paramagnetic resonance measurements and selective quenching experiments. Unlike most of the previous analogous reports, herein, we demonstrate that 1O2 in the presence of PNC1200-4K2CO3 can degrade oxalic acid even in the presence of common radical scavengers.