Enzyme induced cementation of biochar-intercalated soil: fabrication and characterization

This paper presents the effect of adding biochar on the sand treated by a bio-inspired technique known as enzyme-induced carbonate precipitation (EICP). In EICP, free urease enzyme is used to accelerate the reaction between calcium chloride and urea to induce calcium carbonate precipitation in soil pores. A laboratory study was conducted to investigate the efficiency of three different biochars produced at different temperatures (300, 500, and 700 degrees C) and applied at 1% to the soil. The precipitation is expected to change the mechanical properties of the treated soil through binding particles and reducing the impact of the ammonia chloride. The outcome of this study illustrated that adding biochar will decrease the cementation bonding between particles, strength, due surface structure, and functional groups of biochar. Furthermore, lower pH was recorded at a lower pyrolysis temperature compared to a high pyrolysis temperature. However, the high pyrolysis temperature indicated that higher porosity would decrease the efficiency of precipitation. Unconfined compressive strength, scan electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffractometer were illustrated, and the type of precipitation and crystal that form through this study was discussed.