Production, characterization, and potential of activated biochar as adsorbent for phenolic compounds from leachates in a lumber industry site

There is growing interest in low-cost, efficient materials for the removal of organic contaminants in municipal and industrial effluents. In this study, the efficiency of biochar and activated biochar, as promising adsorbents for phenol removal, was investigated at high (up to 1500mgL(-1)) and low concentrations (0.54mgL(-1)) in synthetic and real effluents (from wood-residue deposits in Quebec), respectively. The performance of both materials was then evaluated in batch adsorption experiments, which were conducted using a low solid/liquid ratio (0.1g:100mL) at different phenol concentrations (C-0=5-1500mgL(-1)), and at 20 degrees C. Activated biochars presented higher phenol adsorption capacity compared to biochars due to their improved textural properties, higher micropore volume, and proportion of oxygenated carbonyl groups connected to their surface. The sorption equilibrium was reached within less than 4h for all of materials, while the Langmuir model best described their sorption process. The maximum sorption capacity of activated biochars for phenol was found to be twofold relative to biochars (303 vs. 159mgg(-1)). Results also showed that activated biochars were more effective than biochars in removing low phenol concentrations in real effluents. In addition, 95% of phenol removal was attained within 96h (although 85% was removed after 4h), thus reaching below the maximum authorized concentration allowed by Quebec's discharge criteria (0.05mgL(-1)). These results show that activated biochars made from wood residues are promising potential adsorbent materials for the efficient treatment of phenol in synthetic and real effluents.