铅离子双印迹吸附剂的制备及其在原子吸收光谱法测定水中痕量铅中的应用

Preparation of a Novel Bi-imprinted Adsorbent for Pb(Ⅱ)and Its Application to FAAS Determination of Trace Amount of Lead in Water Sample

采用分子印迹技术,以3-疏基丙基三甲氧基硅烷为功能单体,铅离子和十六烷基三甲基溴化铵(CTMAB)为双模板形式络合体系,并加入由四乙氧基硅烷和甲醇所形成的溶胶,用氢氧化钠作催化剂制得铅离子双印迹吸附剂。经红外光谱法和氮气吸附-脱附系统对此吸附剂的结构特征及表面性能进行表征和分析。结果表明:在印迹吸附剂中除去铅(Ⅱ)离子模板后,恢复了-SH官能团;CTMAB的存在具有提高表面积和孔径的倾向。此双印迹吸附剂在静态条件下,对铅(Ⅱ)离子的吸附经10min,吸附率达95%。吸附容量达545.6mg·g-1。在镉(Ⅱ)离子共存下,相对选择性系数为192。用0.5mol·L-1硝酸溶液5mL即可从吸附剂上洗脱94.4%铅(Ⅱ)。以此吸附剂作为萃取材料分离富集了环境水样中痕量铅(Ⅱ),洗脱后用原子吸收光谱法测定其中铅(Ⅱ)量,测定值的回收率在104%~106%之间。

A novel bi-imprinted adsorbent for Pb(Ⅱ)(abbr.as Pb-BIA)was prepared by the molecular imprinting technique using MPS as functional isomer,Pb(Ⅱ)-ion and CTMAB as pattern plates,TEOS(in CH3OH)as sol and NaOH solution as catalyst.Its structural features and surface properties were characterised and studied by FT-IRS and ASAP2010system.It was shown that in the BIA,Pb(Ⅱ)-pattern plate was removed and functional group of-SH was resumed,and that its surface area and bore diameter were raised by the presence of CTMAB.It was found that under static condition,rate of adsorption of Pb(Ⅱ)by the BIA attained to 95% in 10min;the maximum adsorption capacity was found to be 545.6mg·g-1;and the relative selectivity coefficient found was 192in the presence of Cd(Ⅱ).Rate of desorption of Pb(Ⅱ)from BIA attained to 94.4% when eluted with 5mL of 0.5mol·L-1 HNO3solution.The BIA was used as extractant in SPE for separation and enrichment of traces of Pb(Ⅱ)in an enviromental water sample,and Pb(Ⅱ)was eluted from the column,and determined by FAAS.Values of recovery were found in the range of 104%to 106%.