Sustainable production of value-added sulfonated biochar by sulfuric acid carbonization reduction of rice husks

Biochar is an effective vehicle for sequestering carbon and mitigating the greenhouse gas effect, as a way to combat climate change. Currently pyrolysis is the main treatment method to prepare biochar, and generally only half of the carbon (C) can be retained in the pyrolytic biochar. In this paper, we introduce a new low-cost method for the preparation of biochar from biomass by one-step carbonized reduced sulfuric acid. The results show that the carbonization reaction of rice husk with alkylated waste sulfuric acid can yield more than 80% of biochar, which is much higher than the pyrolysis biochar. Besides, the prepared biomass sulfonated char has abundant functional groups including -(SOH)-H-3, -OH and exhibits excellent adsorption performance for Cd2+ with the maximum adsorption capacity of 93.98 mg/g. In conclusion, the method used in this paper to prepare sulfonated biochar has fewer steps, a lower processing cost and higher value-added products, thus making it more sustainable and economical, and supporting a wider range of sulfuric acid carbonization methods. It has the potential to inspire and lead the way for the safe, economical and sustainable preparation of value-added sulfonated carbon materials for commercial applications. (C) 2021 Published by Elsevier B.V.