Biochars-Fe PCu hybrides deriving from solid waste and waste acids for elimination of refractory organic pollutants from pharmaceutical wastewater

A novel Fe based nanocomposite was fabricated by using solid waste, waste acids, iron ores and copper salts as raw materials. The composites were composed of biochars, iron phosphides, iron carbide and Cu (BC-FexPCu), and applied as pre-treating materials to degrade 3,4,5,6-tetrachloropicolinic acid (TCPA) from saline water. In a wide pH (4–10), temperature (25–65 °C) and salinity (0–25 g L-1 of NaCl) range, TCPA could be eliminated completely within 240 min from saline water with the corresponding mineralization efficiency ranged in 65.4–85.9 %. High concentration of ·OH, O2–· and 1O2 was continuously detected in BC-FexPCu reaction solution owing to efficient activation of dissolved oxygen by BC-FexPCu. The BC-FexPCu showed good performance in pretreating wastewater from a chloropyridine herbicide production plant. In batch experiment, about 60 % of total organic carbon (TOC) was removed from wastewater within 180 min without the requirement of H2O2. In the fixed bed column test, the elimination efficiency of TOC maintained 30 % with the help of discontinuous aeration. The recycle test suggested that the long-lasting activity of BC-FexPCu could be achieved when the targets were degraded only by reactive oxygen species in the system. Compared to zero-valent iron and commercial Fe/C materials, the advantages of BC-FexPCu include good stability, cost-effectiveness, and less chemical requirements.