Paracetamol removal by Kon-Tiki kiln-derived biochar and activated carbons

Abstract

Biochar was obtained from Eucalyptus pruning residues with a non-conventional device named Kon-Tiki kiln. The average heat of combustion of the biochar, 27.3 MJ kg−1, was higher than that of Eucalyptus wood, 17.8 MJ kg−1. Activation with CO2 was performed by varying the activation time from 0 to 60 minutes. The activated carbons (ACs) and the carbon precursor have been characterised and tested for paracetamol removal in the liquid phase, studied in both kinetic and equilibrium aspects. ACs presented an increase in BET area (up to 845 m2/g), total pore volume and microporosity with the activation time. The pseudo-second order model was the one that best fitted the experimental data. Elimination of paracetamol was much faster when using ACs, 5 h, than when using the biochar, 3 days. However, pollutant removal was greater than 95 % for all materials, which is a promising result for low-cost biochars in a difficult economic context. All the adsorption equilibrium experiments exhibited multilayer behaviour, showing values up to 98 mg g−1 for the maximum monolayer-adsorption capacity.