School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
Sci Total Environ. 2018 Jul 1;628-629:499-508. doi: 10.1016/j.scitotenv.2018.02.091. Epub 2018 Feb 13.
FeO@SiO-NH magnetic particles with core-shell structure were attached on carboxylated biochar derived from phoenix tree leaves to synthesize a novel magnetic biochar for removing Cr(VI) ions from acidic solutions. FSEM, FTEM, XRD characterizations of the synthesized magnetic biochar revealed that the FeO@SiO-NH magnetic particles distributed uniformly on the surface or macrospores of carboxylated biochar by strong chemical bonding. The Cr(VI) ions adsorption capacity of magnetic biochar was 27.2mg·g, surpassing original carboxylated biochar (18.2mg·g). VSM and XPS characterizations demonstrated that the attached FeO@SiO-NH magnetic particles not only endowed biochar with perfect magnetic property (23emu·g) but also provided complexing sites for binding Cr(III) cations reduced from Cr(VI) anions. The Cr(VI) ions removal by magnetic biochar contained three steps: (1) adsorption of Cr(VI) anions by protonated functional groups; (2) reduction of Cr(VI) anions to Cr(III) cations by electron-donor groups; and (3) chelation of Cr(III) cations by amine groups. The adsorption recycling test showed that magnetic biochar kept 85% of its initial Cr(VI) adsorption capacity at the sixth cycle, and the Fe leakage under pH1.0 was smaller than 0.25mg·L. The results indicated that this novel magnetic biochar was applicable for the practical treatment of Cr(VI)-containing wastewater.
具有核壳结构的 FeO@SiO-NH 磁性颗粒被附着在由梧桐树叶衍生的羧基化生物炭上，以合成一种新型磁性生物炭，用于从酸性溶液中去除 Cr(VI)离子。合成的磁性生物炭的 FSEM、FTEM 和 XRD 表征表明，FeO@SiO-NH 磁性颗粒通过强化学键均匀分布在羧基化生物炭的表面或大孔上。磁性生物炭的 Cr(VI)离子吸附容量为 27.2mg·g，超过了原始羧基化生物炭（18.2mg·g）。VSM 和 XPS 表征表明，附着的 FeO@SiO-NH 磁性颗粒不仅赋予生物炭完美的磁性（23emu·g），而且还为结合从 Cr(VI)阴离子还原的 Cr(III)阳离子提供了络合位点。磁性生物炭去除 Cr(VI)离子包含三个步骤：（1）质子化官能团吸附 Cr(VI)阴离子；（2）电子供体基团还原 Cr(VI)阴离子为 Cr(III)阳离子；（3）胺基螯合 Cr(III)阳离子。吸附回收测试表明，磁性生物炭在第六个循环时保持了其初始 Cr(VI)吸附容量的 85%，并且在 pH1.0 下的铁泄漏量小于 0.25mg·L。结果表明，这种新型磁性生物炭适用于实际处理含 Cr(VI)废水。
