摘要
采用尿素法制备高结晶度Mg-Al水滑石(MAH),系统研究了Mg-Al水滑石"记忆效应"及其对Cr(Ⅵ)阴离子吸附性能的影响.通过XRD、FT-IR、SEM、DSC以及去卷积分析对MAH、重构"记忆"MAH(RMAH)以及MAH的金属氧化物(MAO)、RMAH的金属氧化物(RMAO)进行表征分析.结果表明,重构的"记忆"RMAH和前体MAH均具高结晶度水滑石层状晶体结构特征,两者晶体结构和层板电荷密度几乎无差异.MAO仍保留层状结构,而再次重构的RMAO中MgAl2O4尖晶石晶相增多,仍有层状结构残留.由于水滑石强结构"记忆效应",使Mg-A1 LDOs(MAO和RMAO)对Cr(Ⅵ)阴离子吸附能力大大强于Mg-A1 LDHs(MAH和RMAH).MAO对Cr(Ⅵ)阴离子吸附能力高于RMAO,可能由于RMAH焙烧形成的RMAO中MgAl2O4尖晶石含量增多及层状结构消减,导致其"记忆效应"重构能力衰减,从而使RMAO对Cr(Ⅵ)阴离子吸附能力下降.
Mg-Al hydrotalcite（MAH） with high crystallinity was prepared using urea method.The ＂memory effect＂ and the chromium（Ⅵ） adsorption property of Mg-Al Hydrotalcites were studied.The MAH,recon-structed MAH（RMAH）,calcined MAH（MAO） and calcined RMAH（RMAO） were characterized by XRD,FT-IR,SEM and DSC as well as self-deconvolution analyses.The results showed that the MAH and RMAH possessed a layered structure of hydrotalcites with high crystallinity,and there was little difference in crystal structures and charge density of brucite-like sheets between MAH and RMAH.The brucite-like sheets were still held in MAO,and a little remained in RMAO with more MgAl2O4.The adsorbility of Mg-A1 LDOs（MAO and RMAO） to Cr（Ⅵ） anions was substantially higher than that of Mg-A1 LDHs（MAH and RMAH）,mainly because of the structure ＂memory effect＂ of hydrotalcites.The adsorbility of the MAO was higher than that of the RMAO.The adsorbility decrease of the RMAO might be due to the increase of the content of spinel MgAl2O4 phase and the decline of brucite-like sheets in RMAO that resulted in the descent of the ＂memory effect＂ reconstruction property.This newly discovery for anionic clays is useful for the de-contamination of waste waters.The Mg-Al hydrotalcite can be considered as a potential material for sorption of anions in wastewater treatment systems.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2011年第8期874-880,共7页
Journal of Inorganic Materials
基金
国家重大科技专项(2009ZX07212-001-03)
国家自然科学基金(20976148)
湖南省研究生科研创新项目(CXZ010B268)~~
