Remediation effect of Cr (VI)-contaminated soil by secondary pyrolysis oil-based drilling cuttings ash

[Display omitted] •The novel utilization avenue of oil-based drilling cuttings ash has been proposed.•OBDCA-sp was used to remediate Cr-contaminated soil.•Addition of OBCDA-sp transformed Cr from an effective state to a stable form.•The mechanism of Cr(VI) transformation in soil has been speculated.•OBDCA-sp could be a promising alternative for remediation of Cr-contaminated soil. In this study, secondary pyrolysis oil-based drilling cuttings ash (OBDCA-sp) was used to remediate chromium (Cr)-contaminated soil. The effects of the OBCDA-sp mesh, OBCDA-sp dosage and soil moisture content on the removal of Cr (VI) were investigated. Subsequently, a kinetic experiment was conducted where the pseudo-first-order and pseudo-second-order kinetic models both fitted well on OBDCA-sp with the adsorption process of Cr (VI) in soil. The change of the chromium form indicated that the addition of OBCDA-sp transformed Cr from an effective state to a stable form, reducing its mobility and bioavailability. X-ray diffraction and Fourier transform infrared spectroscopy analysis were used to verify the potential mechanism of Cr (VI) removal; Ba, Fe, S, and P elements in OBCDA-sp were observed to play a significant role in the reduction of Cr (VI). The results from this study indicate that OBCDA-sp could be an emergent and promising alternative for the remediation of Cr-contaminated soil.