Effects of feedstock type and slow pyrolysis temperature in the production of biochars on the removal of cadmium and nickel from water

Biochar is a universal sorbent suitable in strategies for removing contaminants from both soil and water. This study evaluated the potential of four biochars each produced from a different feedstock for removing Cd and Ni from water. Chicken manure mixed with sawdust (CM), sugarcane straw (SS), rice husk (RH) and sawdust (SW) were used to produce biochar through slow pyrolysis at two temperatures: 350 and 650 °C. The percentage removed and the removal capacity of Cd and Ni from water by biochars at both temperatures used in the pyrolysis followed the order: CM > SS > RH > SW. The removal percentage ranged from 31 to 98% for Cd and 24–72% for Ni, while removal capacity ranged from 0.3 to 12.5 mg g−1 for Cd and 0.2–10.9 mg g−1 for Ni. The type of feedstock had greater influence on the performance of biochars for removing metals than the pyrolysis temperature.