高分散性纳米铁的制备及其表征

Preparation and Activity Test of Dispersed Iron Nanoparticles

以可生物降解的聚苯乙烯磺酸钠(PSS)为分散剂,制备了能稳定分散于水中的零价纳米铁(nZVI)。未改性的零价纳米铁呈规则的球形或椭球形,平均粒径为60～80 nm,经PPS分散后的纳米铁nZVI/PSS则呈现微小的粒状分散在PSS中。pH=8时,与nZVI相比,nZVI/PSS的ζ电位由+9.4 mV降至-36.7 mV,同时等电点也由8.7变为小于5。XPS分析结果显示,nZVI和nZVI/PSS表面元素构成相同,但nZVI/PSS表面有零价铁存在,而nZVI表面则主要由铁的氧化物组成。实验结果表明,两种纳米铁对Cr(VI)的去除率非常接近,在纳米铁投加量为1.0 g.L-1,Cr(VI)初始浓度为100 mg.L-1的条件下,Cr(VI)的去除率在10 min内均能达到95%,在30 min内能达99%,表明nZVI/PSS具有较高活性。

using biod Dispersed nanoscale zero-valent iron （nZVI） dispersed in water up to 2 weeks was synthesized egradable polymer Poly（sodium-p-styrenesulfonate） （PSS） as a stabilizer. The results of TEM indicated that the bare-nZVI are largely spherical or spheroidicity , with a mean partical size of 60-80 nm, while the nZVI/PSS are dispersed in a kind of crystal coat. X-ray photoelectron spectroscopy （XPS） confirmed that the surface element composition of nZVI was just the same as nZVI/PSS, the difference was that there were zerovalent iron on the nZVI while not on the nZVI/PSS. The result of zeta （ ξ）- potential showed that the X-potential of nZVI reduced from ＋ 9.4 mV to -36.7 mV after dispersed with PSS at pH = 8. The isoelectric point （IEP） shifted from pH = 8.7 to less than 5. Batch experiments confirmed that the capacity of effectively reducing hexavalent chromium of nZVI and nZVI/PSS was equivalent. At 1 g · L^-1 iron loading and 100 mg · L^-1 initial Cr（VI） concentration , over 95% Cr（VI） was removed in less than 10 min and 99% in less than 30 min. This result indicated that the laboratory- prepared nZVI/PSS remains high reactivity.