34 9 2013 9 ENVIRONMENTAL SCIENCE Vol 34 No 9 Sep 2013 1 2 1* 1 1 2 1 2 1 2 Marc Peters 1 1 100101 2 100049 EDTA Cd Pb 52 2 mg kg - 1 4 836 5 mg kg - 1 Cr 2 7% 60% Cd Pb 0 1% 0 1 mol L - 1 EDTA 1 6 2 3 h X53 A 0250-3301 2013 09-3690-07 Research on the Effect and Technique of Remediation for Multi-Metal Contaminated Tailing Soils ZHU Guang-xu 1 2 GUO Qing-jun 1 YANG Jun-xing 1 ZHANG Han-zhi 1 2 WEI Rong-fei 1 2 WANG Chun-yu 1 2 Marc Peters 1 1 Center for Environmental Remediation Institute of Geographical Sciences and Natural Resources Chinese Academy of Sciences Beijing 100101 China 2 University of Chinese Academy of Sciences Beijing 100049 China Abstract Soil samples were collected from compound polluted tailings to analyze the contents of total heavy metals and their speciation in the soil Laboratory batch tests were conducted to examine the effects of distilled water and different concentrations of oxalic acid citric acid acetic acid HNO 3 and EDTA on the removal of heavy metals from the polluted soils The suitable eluent and its optimal conditions including liquid to soil ratio reaction time and washing number were also optimized and the total toxicity reduction index was proposed to evaluate the effect of the eluent on the remediation of polluted soil The results showed that Cd and Pb were the most abundant heavy metals in the soil reaching 52 2 mg kg - 1 and 4 836 5 m kg - 1 respectively There was significant difference in the removal efficiency for different heavy metals Cr had a maximum removal efficiency of 2 7% while the maximum Cd and Pb removal efficiency was both about 60% Distilled water had little removal efficiency for heavy metals with less than 0 1 % removal rate the heavy metal removal efficiency of oxalic acid and acetic acid was also quite low EDTA in 0 1 mol L - 1 was selected as the suitable eluent for the polluted soil Evaluation of the total toxicity reduction index and the cost suggested that EDTA should be used with a liquid to soil ratio of 6 1 a reaction time of 3 h and 2 washings Key words heavy metal contaminated soil tailing soil washing remediation total toxicity reduction index 50 t 95% 80% 70% - - 4 1 2 743 hm 2 5 ~ 7 80 51 t 3 2013-01-06 2013-03-08 863 2013AA06A211-2 1986 ~ E-mail woaiwojiahxx@ 163 com * E-mail guoqj@ igsnrr ac cn
9 3691 EDTA DTPA 8 NTA 9 1 EDTA 1 1 1 1 3 2 1 20 2 00 g 20 50 ml 12 ml ph 20 ml 6 1 10 1 100 1 3 1 HNO 3 -HF-HClO 4 10 2 20 2 00 g GSS-1 GSS-5 50 ml 180 r min - 1 25 BCR 11 3 6 12 24 h 3 1 2 1 2 EDTA-Na 2 2 EDTA 14 3 PHS-3B ph 2 ph -Mastersizer 2000 Cd ICP- 2 1 MS ELAN-DRC-e ICP-OES Optima 5300DV Cr Cu Ni Pb Zn 20 min 1 3 5 0% 17 2% 1 3 1 77 8% 2 20 2 00 g 50 ml 20 ml 10 / 1 3 Cd 527 3 > Pb 117 3 > Zn 18 5 > Cu 1 3 16 2 > Cr 3 4 > Ni 1 7 25 GB 15618-1995 Cd 50 180 r min 12 h 3 000 Pb Zn 8 2 Cu r min - 1 Cd Pb Zn Cu Table 1 Test eluents and their concentrations /mol L - 1 0 05 0 1 0 2 0 05 0 1 0 2 0 05 0 1 0 2 0 2 0 5 1 EDTA 0 05 0 1 0 2 2 1 ph 6 34
3692 34 2 /mg kg - 1 Table 2 Contents of heavy metal in test soil and reference standard values /mg kg - 1 Cd Cr Cu Ni Pb Zn 52 2 246 6 620 1 85 4 4 836 5 1 719 4 0 099 72 4 38 38 50 68 41 24 92 82 1 0 300 400 200 500 500 13 ~ 15 ph 16 ~ 18 1 Fig 1 Speciation distribution of heavy metals in test soil BCR 1 Cd 40% Cd Pb Cd 60% Cu Zn 30% Cu Cu Ni 1% 70% Pb 17% Zn Ni Cr Cd Pb 24 6% Ni Cr ph 19 20 Cd Pb 21 Wasay 22 Cr Zn Cu Cr + Cr 94 7% Zn Cu 70% Mn Hg Pb 43% ~ 45% 37% ~ 54 3% Zn 41% 91% ~ 92% 75% 16 5% 7 6% Cu 98% Cd 89% Pb 91% 30 2% 8 7% Ni Cd 87% Pb 40% Cd Cu Pb Zn 84% ~ Ni 13 8% 91% 73% ~ 84% 56% ~ 70% 72% ~ 81% 2 2 23 80 mmol L - 1 Cd 2 5 Cu Pb 90 4% 82 5% 38 6% Cd Cr Cu Zn 0 07% Cd Pb
9 3693 Fig 2 2 Removal efficiency for the heavy metals by different eluents in a series of concentrations EDTA Cd Cu Pb Zn 2 3 ~ 24 h Cu Pb Zn Pb EDTA Cd Zn 60% Cd Zn 13% ~ 17% Cu EDTA Pb EDTA EDTA 65% Pb 28% 21 33% 24 Pb 2 3 1 10 EDTA 1 6 Cd Zn 1 10 Cd Pb 24 h Pb 1 6 0 1 mol L - 1 EDTA 26 6% 1 6 1 10 14 9% 38 5% Cd 2 3 EDTA Makino 25 3 Cd
3694 34 1 1 5 1 10 3 h 6 h 6 h 12 h 3 Fig 3 3 EDTA Removal efficiency for the heavy metals under different EDTA washing condition 27 28 Hakanson 26 L L = Σ n i = 1 = Σ n B i r E i r = Σ n i = 1 B i r T i r C i s /C i n B i r T i r C i r EDTA 4 1 10 2 i = 1 3 h B i r C i s C i n CdEDTA T i r Cd Cd 1 6 2 Hakanson 3 h 1 6 3 h 2
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