Co2 Dual Roles In Food Scraps-Derived Biochar Activation To Enhance Lead Adsorption Capacity

Driven by China's waste classification system, the recycling of food scraps is a work of great importance. The carbonate (CO32-) and phosphate (PO43-) in food scraps indicate that its derived biochar can be a good candidate for Pb immobilization. In the current study, Pb2+ adsorption sites (CO32- and PO43-) of biochar were adjusted by carrier gas atmosphere and activation temperature. Results indicate that CO2 has dual roles in activation of food scraps-derived biochar. CO2 can not only inhibit the decomposition of CO32- but also increase the content of PO43- via consuming aromatic carbon combined with phosphorus at high temperature (>600 degrees C). Thus, the biochar prepared at 700 degrees C and CO2 atmosphere has more adsorption sites, resulting in an outstanding Pb adsorption capacity (up to 555.6 mg/g) via coprecipitation mechanisms. As-prepared biochar sample also can be prepared to a hydrogel with a remarkable mechanic strength. But biochar hydrogel decreases Pb adsorption capacity to 104.2 mg/g due to the pore blocking effect. Life cycle assessment illustrates that the scene of food scraps activated by CO2 has lower Global Warming Potential (GWP) and Primary Energy Demand (PED). Therefore, current research provides a high-efficiency method for treatment of food scraps.