1.China Merchants Ecological and Environmental Protection Technology Co., Ltd;2.College of Environment and Ecology, Chongqing University
Chongqing technology innovation and application demonstration project (No. cstc2018jszx-zdyfxmX0017); China merchants ecological and environmental protection technology co., LTD. Science and technology innovation project (No. 190351)
Solidification/stabilization was an effective means for the remediation of chromium (Cr)-contaminated soil. Different agents differ in their abilities of Cr-reduction, adsorption and stabilization. Screening agents that are low-cost and high-efficiency is vital to remediate Cr-contaminated soil. In the present study, seven reductants, ten adsorbents and six stabilizers in different doses were used as amendments to remediate Cr-contaminated soil, respectively. The main findings were as follows: (1) Calcium polysulfide (CPS), sodium sulfide (Na2S), ferrous chloride (FeCl2) and ferrous sulfate (FeSO4) can be used as reducing materials of Cr-contaminated soil. CPS had the best Cr (VI)-stability efficiency exceeding 90% when it was added at the mole ratio of 0.8. (2) Calcium magnesium phosphate (CMP), weak-base anion-exchange resin (WAR), magnesium oxide (MgO) and diaspore (Al2O3·3nH2O) can be used as absorbing materials of Cr-contaminated soil. CMP demonstrated the best adsorptivity with Cr (VI)-stability efficiency being above 90% and total Cr 80% when it was added at the mass ratio of 20%. (3) Furnace slag powder (FSP, bought from Chongqing and Henan) and sodium silicate (Na2SiO3·9H2O) can be used as immobilizing materials of Cr-contaminated soil. FSP from Chongqing was the best in immobilizing Cr (VI) with stability efficiency reaching 98% and total Cr higher 70% when it was added at the mass ratio of 16%. In conclusion, the materials used in this study played important role in remediation of Cr-contaminated soil and achieved the high Cr (VI)-stability efficiency under laboratory conditions. Their potential value as Cr-immobilizers and their remediation efficacy deserve further studies in large-scale field trials.