| Professional Committee of Rock and Mineral Testing Technology of the Geological Society of China, National Geological Experiment and Testing Center | Host |
| Citation: |
ZHU Hong, LIU Jing, JIAO Han-tao, ZHANG Jing, DUAN Jiang-tao, LIAN Xing-ye, HOU Ya-nan. Effect of Molecular Structure in Chlorinated Organic Compounds on Zero-valent Copper Degradation Mechanism Based on SEM-EDS and GC-MS Techniques[J]. Rock and Mineral Analysis, 2015, 34(2): 169-175. doi: 10.15898/j.cnki.11-2131/td.2015.02.003
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Effect of Molecular Structure in Chlorinated Organic Compounds on Zero-valent Copper Degradation Mechanism Based on SEM-EDS and GC-MS Techniques
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Abstract
Zero-valent copper, even cheap, is rarely used in hydrodechlorination (such as chlorinated aromatic hydrocarbons), because Cu has poor catalytical dechlorination activity and complex reaction mechanisms. In this study, Cu-Fe and Cu-Ni alloys were prepared by mechanical ball-milling, and the effect of micro-environment for the chlorophenol (4-CP) dechlorination behavior of Cu was studied in order to investigate the effect of organic chlorine molecular structure on Cu dechlorination. Two reaction mechanisms were examined for low-cost copper during dechlorination. SEM-EDS and GC-MS analyses show that the structure of organic chlorine and Cu metal environment could directly affect the mechanism. In the Cu-Fe system, Cu follows the classic catalytic hydrodechlorination mechanism and the degradation product 4-CP is phenol. But in the Cu-Ni system, nickel metal does not play a catalytic hydrogenation of action, the degraded product for 4-CP by Cu-Ni alloy is cyclohexanone. Copper acts as hydrogen-metal and shows a strong reducing activity by direct electron transfer. 4-CP degradation for Zero-valent copper was up to 70%, while only 34% for Cu-Fe system. These differences concluded that the aromatic ring was a direct electron transfer for Cu. Zero-valent copper can degrade 4-CP and phenol with high chemical stability, but cannot degrade aliphatic chlorinated organics (e.g., monochloroacetic acid and dichloroacetic acid) with relatively poor chemical stability. In conclusion, dechlorination mechanism for zero-valent copper is not traditional catalytic hydrodechlorination, but the direct electron transfer reduction mechanism which is affected by target molecule structure.
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References
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ZHU Hong, LIU Jing, JIAO Han-tao, ZHANG Jing, DUAN Jiang-tao, LIAN Xing-ye, HOU Ya-nan. Effect of Molecular Structure in Chlorinated Organic Compounds on Zero-valent Copper Degradation Mechanism Based on SEM-EDS and GC-MS Techniques[J]. Rock and Mineral Analysis, 2015, 34(2): 169-175. doi: 10.15898/j.cnki.11-2131/td.2015.02.003
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Figure 1.
SEM-EDS images for ball-milled Cu-Fe alloy
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Figure 2.
degradation with different composition ratio of Cu-Fe(a), and Cu-Ni(b) alloy at the initial pH=2
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Figure 3.
Compound concentrations during the degradation for 50 mg/L 4-CP solution with initial pH=3. The ball-milling time was 6 h for Cu-Fe or Cu-Ni alloy
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Figure 4.
Degradation of 100 g/L copper power dosage for (a) 50 mg/L phenol, (b)500 mg/L monochloroacetate and dichloroacetate
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Figure 5.
(a) Degradation for 50 mg/L 4-CP solution, initial pH=5, with 100 g/L dosage Cu power; (b) Degradation and total organic carbon for 4-CP in HCl solution, with 100 g/L dosage Cu power