Emerging micro-contaminant adsorption from water and wastewater using CNT-doped biochar nanocomposites from rice husks and sewage sludge

Abstract In this study, rice husks (RH) and sewage sludge (SS) were used as feedstock to produce carbon nanotube (CNT)-doped biochar nanocomposites at two pyrolytic temperatures, 400 °C and 600 °C. The samples were produced, physicochemically and structurally evaluated, and tested as adsorbents for the extraction of six organic micro-contaminants of emerging concern (EMCs) in as-close-to-realistic concentrations, from water and wastewater. RH biochar nanocomposites were more effective than SS biochar nanocomposites on the adsorption of EMCs, requiring lower adsorption times (5 min as compared to 10 min) to sufficiently remove (> 80%) the investigated pollutants. This was in agreement with the physicochemical analysis of biochar nanocomposites which showed a more developed porous structure for RH samples. The dominant mechanisms in the adsorption process were proven to be π-π EDA interactions accompanied by pore-filling mechanisms, along with hydrophobic and electrostatic interactions, in a less dominant role. This study showed that RH and SS biochar nanocomposites have the potential to be effectively used to decontaminate water and wastewater from emerging pollutants.