High efficiency removal of As(III) from waters using a new and friendly adsorbent based on sugarcane bagasse and corncob husk Fe-coated biochars

Water contamination of As is a big issue in many areas around the globe. Therefore, cheap and efficient techniques are essential facing traditional treatment methods. Then, biochars (BC) emerged recently as material that can be used for As removal. However, research about efficiency of BC produced from local feedstock is still needed. The purpose of this study is to assess the efficiency of BC produced from sugarcane bagasse (SB) together with corncob husk (CH) with and without Fe(III) (BC_Fe) modification to be used for removal of As(III) from waters. The BC and BC_Fe produced at different pyrolysis temperatures were characterised using FTIR and SEM/EDS. Adsorption capacities of BC and BC_Fe were evaluated via batch adsorption, desorption and column tests and their performance was compared with adsorption using activated carbon. The results showed that Fe modification improve substantially the As(III) adsorption in a way that both BC_Fe-SB and BC_Fe-CH removed from 85% to 99.9% from 1000 µg/L As(III) solutions. Both materials fitted well in Langmuir model and the maximum adsorption capacity was 20 mg/g for BC_Fe-SB and 50 mg/g for BC_Fe-CH. The adsorption kinetics of BC_Fe was fast (≤ 30 min) and it had a better performance than activated carbon. The column tests showed that the process is efficient even at high As(III) concentrations. The fast removal process and good removal results make the BC_Fe-SB and BC_Fe-CH attractive for in situ and commercial (filters) use, since time and efficiency are required in new technologies.