School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, China; State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China.
Sci Total Environ. 2021 Mar 10;759:143481. doi: 10.1016/j.scitotenv.2020.143481. Epub 2020 Nov 11.
Alginate has been widely employed to increase the performance of nanoscale zerovalent iron (nZVI)-based materials for site remediation. Yet, the effects of alginate on reactivity of sulfidated nZVI (an efficient reductant material) towards contaminants have been understood poorly. In this study, we have developed a one-step synthesis of alginate-coated sulfidated nZVI (S-nZVI@alginate) under air atmosphere and evaluated the reactivity of S-nZVI@alginate towards tetrabromobisphenol A (TBBPA) debromination. Surface analysis shows that S-nZVI has been successfully coated by alginate through the interaction of OH and COO groups of alginate with Fe species. The coating of alginate increases particle stability and dispersion under various conditions and facilitates FeS precipitation on the particle surface. Reactivity experiments show that the coating of alginate significantly enhances TBBPA debromination by S-nZVI. The optimized alginate to Fe weight ratio of S-nZVI@alginate is 0.06, with ~3-fold greater TBBPA debromination rate than S-nZVI. S-nZVI@alginate can completely debrominate TBBPA into bisphenol A via a four-sequential step debromination pathway while S-nZVI not. Its superior reactivity may be attributed to that the formation of alginate-Fe complex can lower the redox potential of Fe species to accelerate electron transfer on the particle surface. The TBBPA debromination rate by S-nZVI@alginate is initially enhanced followed by a decrease with an increase in TBBPA concentration, while it can increase 3.3-, 8.9- and 5.6-fold by increasing S-nZVI@alginate dosage, decreasing pH and adding co-contaminant Cd, respectively. S-nZVI@alginate has greater performance in aging and reusability tests than S-nZVI, and achieves rapid TBBPA removal from wastewater, which may be due to the role of alginate on inhibiting surface oxidation of Fe and S species. Taken together, these results suggest that S-nZVI@alginate provides better reactivity, longevity and reusability than S-nZVI, having the great potential for application into site remediation.
海藻酸钠被广泛应用于提高纳米零价铁（nZVI）基材料在现场修复中的性能。然而，海藻酸钠对硫化纳米零价铁（一种有效的还原剂材料）对污染物的反应性的影响还了解甚少。在本研究中，我们在空气气氛下开发了一种一步合成海藻酸钠包覆硫化纳米零价铁（S-nZVI@alginate）的方法，并评价了 S-nZVI@alginate 对四溴双酚 A（TBBPA）脱溴的反应性。表面分析表明，S-nZVI 通过海藻酸钠中的 OH 和 COO 基团与 Fe 物种的相互作用，成功地被海藻酸钠包覆。海藻酸钠的包覆增加了颗粒在各种条件下的稳定性和分散性，并促进了 FeS 在颗粒表面的沉淀。反应性实验表明，海藻酸钠的包覆显著增强了 S-nZVI 对 TBBPA 的脱溴作用。S-nZVI@alginate 中优化的海藻酸钠与 Fe 的重量比为 0.06，比 S-nZVI 的 TBBPA 脱溴率高约 3 倍。S-nZVI@alginate 可以通过四步连续脱溴途径将 TBBPA 完全脱溴为双酚 A，而 S-nZVI 则不能。其优越的反应性可能归因于海藻酸钠-Fe 配合物的形成可以降低 Fe 物种的氧化还原电位，从而加速颗粒表面的电子转移。S-nZVI@alginate 对 TBBPA 的脱溴速率最初随 TBBPA 浓度的增加而增加，随后降低，而通过增加 S-nZVI@alginate 的用量、降低 pH 值和添加共存污染物 Cd，其脱溴速率分别提高了 3.3 倍、8.9 倍和 5.6 倍。S-nZVI@alginate 在老化和可重复使用性测试中的性能优于 S-nZVI，并且可以从废水中快速去除 TBBPA，这可能是由于海藻酸钠在抑制 Fe 和 S 物种表面氧化方面的作用。综上所述，这些结果表明，S-nZVI@alginate 比 S-nZVI 具有更好的反应性、耐久性和可重复使用性，在现场修复中具有很大的应用潜力。
