Rapid remediation of pharmaceuticals from wastewater using magnetic Fe3O4/Douglas fir biochar adsorbents

Modification of commercially available Douglas fir biochar (BC) by iron oxide nanoparticle precipitation from aqueous Fe2+/Fe3+ salt solutions upon NaOH treatment generated a hybrid adsorbent (MBC) that removed three common emerging aqueous contaminants, a stimulant (caffeine) and two anti-inflammatory drugs (ibuprofen and acetylsalicylic acid) through batch sorption. Fe3O4 particles (12.3 +/- 7.1 nm diameter fundamental particles with aggregates 1-17 mu m diameter) dispersed on the biochar surface provided magnetization and created new adsorption sites for the contaminant uptake. These smaller quasi-spherical, octahedral Fe2O3 particles as well as the spindle-like Fe2O3 particles were observed with scanning electron microscopy (SEM) images of MBC, and the composition was confirmed by X-ray powder diffraction (XRD). Adsorption features were evaluated using Langmuir and Freundlich isotherm models. The Langmuir adsorption capacities on MBC at 35 degrees C have increased from 24.6 +/- 0.4 to 75.1 +/- 1.8 mg/g for caffeine, 17.5 +/- 0.4 to 39.9 +/- 1.2 mg/g for ibuprofen and 106.2 +/- 2.8 to 149.9 +/- 4.5 mg/g for acetylsalicylic acid after Fe2O3 modification. Fast adsorption resulted in equilibrium within 5 min. MBC has potential as a low cost, green adsorbent for pharmaceutical mitigation from water with high adsorption capacities and fast kinetics. The Douglas fir biochar is a byproduct waste from a syn-gas from wood production process covering its production costs. Published by Elsevier Ltd.