Preparation of biochar from pyrolysis of soybean straw at different pyrolysis temperature for cadmium removal from wastewater and pyrolysis gas investigation

The Cd2+ adsorption performance of biochar derived from soybean straw pyrolysis at 400–600 °C is investigated. Langmuir model can accurately describe the Cd2+ adsorption data with adsorption amount of 47.30 mg/g with pH=5. Cd2+ adsorption kinetic process could be analyzed using Pseudo-second-order. Biochar has large Cd2+ wastewater treatment volume, based on column adsorption experiment. The π-electrons play an important role in Cd2+ adsorption, based on adsorption mechanism analysis. Biochar has good stability after three cycles. Biochar also has good application potential used in lithium ion battery anode with specific capacity of 132 mA g−1. Besides, pyrolysis gas is recycled in the preparation process of biochar with heating value of the 12.10 MJ/Nm3. These results indicate that soybean straw waste is converted into sustainable adsorbent for Cd2+ wastewater treatment.