Development and characterization of activated carbon from pine sawdust waste for removal of 17-α-ethinylestradiol in a water model

Activated carbon biosorption is a feasible alternative for both the removal of emerging contaminants from water and for the utilization of agro-industrial waste. 17-α-ethinylestradiol (EE2) is a hormone considered an emerging contaminant in water bodies, which causes physiological alterations in aquatic animals and ecological problems in aquatic ecosystems. In Mexico, 2.3 million cubic meters of agroforestry waste are generated in the sawmill industry. The primary waste from this industry is sawdust, which is either used as fuel or left in fields, thereby causing pollution. The aim of the current study was to determine the potential of activated carbons made from pine sawdust using inexpensive methods (different H3PO4 treatments) for the removal of EE2 in a water model. The biosorbents were characterized by their yield and surface changes using infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and specific surface area analysis with the Brunauer-Emmett-Teller (BET) method. To determine the EE2 removal capacity, five concentrations of activated carbon (68, 400, 1200, 2000, and 2331 mg/L) at different pH conditions (1.7, 3, 6, 9 and 10.2), and an EE2 solution (400 mg/L water-ethanol, 7:3 v/v) were used. EE2 quantification was carried out by high-performance liquid chromatography with a photodiode array detector (HPLC-PDA). Three activated carbons were prepared, highlighting specific surface area (from 543 to 571.7 m2/g). Although there were no significant differences, the highest EE2 removal (26.92%) was obtained with activated carbon 2 (AC2) for a treatment of 2331 mg/L and pH 6. The results revealed that pine sawdust is an adequate material for producing efficiently activated carbon for removing EE2 from water through inexpensive methods.