Immobilization and mitigation of chromium toxicity in aqueous solutions and tannery waste-contaminated soil using biochar and polymer-modified biochar

This study was conducted to investigate the potential of Jujube (Ziziphus jujube L) wood waste-derived biochar (BC) and its derivative polymer-modified biochar (PBC) in removing hexavalent chromium (Cr-VI) from aqueous solutions and in achieving Cr stabilization in tannery waste-contaminated soil. BC was produced at three different pyrolysis temperature (300 degrees C, 500 degrees C, 700 degrees C) and was polymerized with acrylamide and N, N1 methylenebisacrylamide. The results showed that Cr-VI adsorption is a function of the pH and Cr-VI initial concentration of the solution. The PBC showed highest sorption efficiency for Cr-VI removal, which amounted to 76.4%-99.6% of the Cr-VI overall initial concentrations (5 -40 mg L-1) at an initial pH of 2. In greenhouse, wheat (Triticum aestivum L) was cultivated as a test crop in pots with tannery waste-contaminated soil along with BCs and PBCs amendments. The BC and PBC amended soil showed 47.7% and 65% less Cr uptake by the plant roots in comparison with unamended soil, respectively. In addition, zero concentration of Cr in the plant shoots was noted with the PBC-amended soil, while the Cr concentration in the shoots was decreased by 89% with the BC-amended soil. Thus, it was concluded that BC and PBC have great potential in removing Cr-VI from aqueous phases and in decreasing the Cr mobility and bioavailability in soil. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study found that biochar and polymer-modified biochar have great potential in removing hexavalent chromium from aqueous phases and in decreasing the mobility and bioavailability of chromium in soil.