Spent Ganoderma lucidum substrate derived biochar as a new bio-adsorbent for Pb2+/Cd2+ removal in water.

The present study firstly reports spent Ganoderma lucidum substrate derived biochars (SLBCS) for the effective removal of Pb2+/Cd2+ from water. The effects of pyrolysis temperature on the SLBCS characteristics and Pb2+/Cd2+ adsorption mechanism was studied systematically. The surface physicochemical properties of SLBCS were significantly affected by the pyrolysis temperature. The increase in pyrolysis temperature from 250 to 650 °C resulted in a drastic increase in the biochar surface area and the well development of mesoporous structure, which could provide more effective adsorption sites for Pb2+ and Cd2+ onto SLBCS. According to the Langmuir model, the obtained maximum adsorption capacity of Pb2+ onto SL650 reached 262.76 mg g-1, while that of Cd2+ reached 75.82 mg g-1. The adsorption capacities of SL650 for Pb2+ and Cd2+ were even higher than that of other modified biochars. The high adsorption capacity of SL650 for Pb2+, attributed to the precipitation supported by high temperature, benefitted the formation of carbonate minerals. Two possible mechanisms involved in Cd2+ sorption: carbonate precipitation and coordination with π electrons. Desorption of SL650 showed high efficiency for Pb2+, but slightly low efficiency for Cd2+. These results indicate that SL650 can be applied for removing heavy metals, especially Pb2+, from polluted water.