镧掺杂纳米材料合成及其高氟选择性吸附特性

采用共沉淀法制备了镧渗杂的纳米镁铝层状双氢氧化物材料(LDHs),获得了一类对氟具有选择性的新型吸附材料.实验表征了LDH、其焙烧产物(LDOs)以及吸附氟后的材料(F-LDHs)的微观形态、体相组成等性质的变化,通过批处理试验和吸附柱试验对其工艺特性及影响因素进行了深入分析.实验结果表明,材料经600℃焙烧10min,在含200mg·l~(-1)SO_4~(2-),氟浓度为10mg·l~(-1)的配水中投加0.1g LDOs吸附240min,最高除氟率可达93.53%;在含200mg·l~(-1)SO_4~(2-)的氟溶液中,镁铝铜LDOs吸附氟的容量高于镁铝LDOs;吸附柱实验中,14h时出水氟含量小于国家标准(1 mg·l~(-1));共存阴离子对材料的除氟干扰强度排序为:Co_3~(2-)>PO_4~(3-)>NO_3~->Cl~-.材料吸附氟后可用0.5mg·l~(-1)的Na_2CO_3洗脱,并经600℃焙烧10min再生,再生4次后选择性除氟效果稳定.

SYNTHESIS OF La DOPED NANO MATERIALS USED IN HIGH-SELECTIVE DEFLUORINATION

A defluorination nano-material La-doped layered double hydroxides (LDHs) was synthesized by coprecipitation in this study. The microstructure and component of LDHs, its calcined and fluoride-adsorbed products, LDOs and F-LDHs, were characterized by SEM, XRD and XRF. In addition, defluorination performance and influence factors of LDHs were adequately analyzed through batch and adsorption column and experiments. The results showed that, for 10 mg F ·l~(-1) water containing 200mg·l~(-1)SO_4~(2-), and with 240 min reacting time, the maximum fluoride removal rate reached 93.53% using an adsorbent of LDO calcined 10 min at 600℃. Moreover, adsorption capacity of Mg/Al/La LDOs was larger than that of Mg/Al LDOs, and the adsorption behaviors are fit with Freundlich adsorption isotherm. Fluoride adsorption was slightly influenced by inorganic anions in solution in the following order CO_3~(2-)> PO_4~(3-) > NO_3~- > Cl~-. In addition, after elution with Na_2CO_3 solution and 10 min calcination at 600℃, the adsorbent was regenerated for 4 experimental cycles.