Transformation of polychlorinated biphenyls （PCBs） by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl （4-C1BP） by nanosca...Transformation of polychlorinated biphenyls （PCBs） by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl （4-C1BP） by nanoscale zero-valent iron （NZVI） in the presence of humic acid or metal ions was investigated. The results showed that the dechlorination of 4-C1BP by NZVI increased with decreased solution pH. When the initial pH value was 4.0, 5.5, 6.8, and 9.0, the de.chlorination efficiencies of 4-CIBP after 48 hr were 53.8%, 47.8%, 35.7%, and 35.6%, respectively. The presence of humic acid inhibited the reduction of 4-CIBP in the first 4 hi＇, and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr. Divalent metal ions, Co2＋, Cu2＋, and Ni2＋, were reduced and formed bimetals with NZVI, thereby enhanced the dechlorination of 4-CIBP. The dechlorination percentages of 4-CIBP in the presence of 0.1 mmol/L Co2~, Cuz~ and Niz~ were 66.1%, 66.0% and 64.6% in 48 hr, and then increased to 67.9%, 71.3% and 73.5%, after 96 hr respectively. The dechlorination kinetics of 4-C1BP by the NZVI in all cases followed pseudo-first order model. The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.展开更多
研究了采用碱溶酸析法配加高剪切技术制备的纳米腐植酸对重金属镉离子的吸附性能,用原子力显微镜（AFM）、红外光谱（FT-IR）、扫描电子显微镜（SEM）、比表面积测试仪（BET）等对纳米腐植酸进行表征,绘制了静态平衡吸附等温线及吸附动...研究了采用碱溶酸析法配加高剪切技术制备的纳米腐植酸对重金属镉离子的吸附性能,用原子力显微镜（AFM）、红外光谱（FT-IR）、扫描电子显微镜（SEM）、比表面积测试仪（BET）等对纳米腐植酸进行表征,绘制了静态平衡吸附等温线及吸附动力学曲线。实验结果表明：吸附剂纳米腐植酸对镉离子的吸附较符合Freundlich模型,在288-308 K温度下,吸附焓变？H=24.22 k J？mol？1,表明吸附是吸热过程,吸附动力学符合HO二级吸附速率方程,反应的表观活化能Ea=25.58 k J？mol？1,表明纳米腐植酸对重金属离子的吸附是化学反应控制,而非扩散所控。吸附剂纳米腐植酸解吸再生循环使用5次后,Cd2＋的吸附容量仅减少18.9%,说明该吸附剂具有较好的解吸再生性能。展开更多
As a promising in situ remediation technology, nanoscale zero-valent iron （nZVI） can remove polybromi- nated diphenyl ethers such as decabromodiphenyl ether （BDE209） effectively, However its use is limited by its ...As a promising in situ remediation technology, nanoscale zero-valent iron （nZVI） can remove polybromi- nated diphenyl ethers such as decabromodiphenyl ether （BDE209） effectively, However its use is limited by its high production cost. Using steel pickling waste liquor as a raw material to prepare nanoscale zero-valent metal （nZVM） can overcome this deficiency. It has been shown that humic acid and metal ions have the greatest influence on remediation. The results showed that nZVM and nZVI both can effectively remove BDE209 with little difference in their removal efficiencies, and humic acid inhibited the removal efficiency, whereas metal ions promoted it. The promoting effects followed the order Ni2＋ 〉 Cu2＋ 〉 Co2＋ and the cumulative effect of the two factors was a combination of the promoting and inhibitory individual effects. The major difference between nZVM and nZVI lies in their crystal form, as nZVI was found to be amorphous while that of nZVM was crystal. However, it was found that both nZVM and nZVI removed BDE209 with similar removal efficiencies. The effects and cumu- lative effects of humic acid and metal ions on nZVM and nZVI were very similar in terms of the efficiency of the BDE209 removal.展开更多
基金supported by the National Basic Research and Development Program (973) of China (No. 2007CB936604)
文摘Transformation of polychlorinated biphenyls （PCBs） by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl （4-C1BP） by nanoscale zero-valent iron （NZVI） in the presence of humic acid or metal ions was investigated. The results showed that the dechlorination of 4-C1BP by NZVI increased with decreased solution pH. When the initial pH value was 4.0, 5.5, 6.8, and 9.0, the de.chlorination efficiencies of 4-CIBP after 48 hr were 53.8%, 47.8%, 35.7%, and 35.6%, respectively. The presence of humic acid inhibited the reduction of 4-CIBP in the first 4 hi＇, and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr. Divalent metal ions, Co2＋, Cu2＋, and Ni2＋, were reduced and formed bimetals with NZVI, thereby enhanced the dechlorination of 4-CIBP. The dechlorination percentages of 4-CIBP in the presence of 0.1 mmol/L Co2~, Cuz~ and Niz~ were 66.1%, 66.0% and 64.6% in 48 hr, and then increased to 67.9%, 71.3% and 73.5%, after 96 hr respectively. The dechlorination kinetics of 4-C1BP by the NZVI in all cases followed pseudo-first order model. The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.
文摘研究了采用碱溶酸析法配加高剪切技术制备的纳米腐植酸对重金属镉离子的吸附性能,用原子力显微镜（AFM）、红外光谱（FT-IR）、扫描电子显微镜（SEM）、比表面积测试仪（BET）等对纳米腐植酸进行表征,绘制了静态平衡吸附等温线及吸附动力学曲线。实验结果表明：吸附剂纳米腐植酸对镉离子的吸附较符合Freundlich模型,在288-308 K温度下,吸附焓变？H=24.22 k J？mol？1,表明吸附是吸热过程,吸附动力学符合HO二级吸附速率方程,反应的表观活化能Ea=25.58 k J？mol？1,表明纳米腐植酸对重金属离子的吸附是化学反应控制,而非扩散所控。吸附剂纳米腐植酸解吸再生循环使用5次后,Cd2＋的吸附容量仅减少18.9%,说明该吸附剂具有较好的解吸再生性能。
基金This research was supported by National Natural Science Foundation of China （Grant No. 41471259） and Guangdong Technology Research Centre for Ecological Management and Remediation of Urban Water Systems （No. 2012 gczxA005）. The authors are grateful to all study participants and thanks for the financial support of the Guangdong Technology Research Centre for Ecological Management and Remediation of Water Systems.
文摘As a promising in situ remediation technology, nanoscale zero-valent iron （nZVI） can remove polybromi- nated diphenyl ethers such as decabromodiphenyl ether （BDE209） effectively, However its use is limited by its high production cost. Using steel pickling waste liquor as a raw material to prepare nanoscale zero-valent metal （nZVM） can overcome this deficiency. It has been shown that humic acid and metal ions have the greatest influence on remediation. The results showed that nZVM and nZVI both can effectively remove BDE209 with little difference in their removal efficiencies, and humic acid inhibited the removal efficiency, whereas metal ions promoted it. The promoting effects followed the order Ni2＋ 〉 Cu2＋ 〉 Co2＋ and the cumulative effect of the two factors was a combination of the promoting and inhibitory individual effects. The major difference between nZVM and nZVI lies in their crystal form, as nZVI was found to be amorphous while that of nZVM was crystal. However, it was found that both nZVM and nZVI removed BDE209 with similar removal efficiencies. The effects and cumu- lative effects of humic acid and metal ions on nZVM and nZVI were very similar in terms of the efficiency of the BDE209 removal.
