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| Stabilization of cadmium in soil using modified red mud-zeolite composite material |
| Received:October 16, 2015 |
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| KeyWord:modified red mud;zeolite;cadmium;available silicon;stabilization |
| Author Name | Affiliation | E-mail | | ZHU Qing | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | LUO Hui-li | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China
Engineering and Technology Center of Pollution Control of Breeding of Livestock-Poultry and Agricultural Planting in Hunan Environment Protection, Changsha 410128, China | luohuili770121@126.com | | WU Gen-yi | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China
Engineering and Technology Center of Pollution Control of Breeding of Livestock-Poultry and Agricultural Planting in Hunan Environment Protection, Changsha 410128, China | | | ZHOU Ying | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | |
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| Abstract: |
| A composite material of modified red mud and zeolite was used to stabilize cadmium in soil. Different fractions of soil Cd were extracted by sequential extraction. Available silicon and pH values in soil were also measured to analyze their effects on Cd stabilization. Results showed that zeolite had a great influence on soil pH, with the largest pH value of 8.36 observed at 5% zeolite. But modified red mud had little effect on soil pH even combined with zeolite, with pH ranging from 6.92 to 7.21. Adding modified red mud and zeolite composite material obviously increased available silicon in soil. As high as 359.1% increase was found at 10% application rate of the composite materials(red mud:zeolite=3:1). At 5% composite material, the greatest stabilization of soil Cd occurred, and exchangeable and carbonate Cd decreased by 79.31% and 45.17%, respectively, while residual Cd fraction increased by 170.84%. The increases in residual Cd were significantly correlated with the decreases in iron manganese oxides-bound Cd(R=-0.975 1). The present results suggest that the ratios of modified red mud and zeolite should be no more than 3:1, and that applying this composite material not only increases soil available silicon but also promotes the transformation of exchangeable-, carbonates-, and iron manganese oxides- Cd to residual Cd. |
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