Non-competitive adsorption of polycyclic aromatic hydrocarbons and heavy metals on activated carbon produced from flax shives

Significant anthropogenic activities have contributed to water pollution with harmful contaminants such as Polycyclic Aromatic Hydrocarbons (PAHs) and heavy metals. This study focuses on the use of a co-product from the flax fiber industry (i.e. activated carbon coming from flax shives after pyrolysis) as bio-adsorbent. First, for the modelling step, water was doped with anthracene, fluoranthene, and benzo(b)fluoranthene at concentrations similar to those found in runoff waters (at the µg L⁻¹ range). Various factors affecting pollutant adsorption were examined in single and multi-compound systems, including FSAC (flax shive activated carbon) concentration, initial PAH concentration and contact time. Within this concentration range, results indicated the absence of competition for anthracene and fluoranthene. Maximum adsorption capacities determined for multi-compound systems were: 4.4, 60.0, and 10.1 mg g⁻¹ for anthracene, fluoranthene, and benzo(b)fluoranthene, respectively. Subsequently, the competitive effect involving another type of pollutant was examined, showing that the adsorption of anthracene and fluoranthene remained unchanged despite the addition of six heavy metals. Finally, various runoff water samples from pond, urban and rural areas were treated, and the adsorption rates were still very high whatever the type of water.