双硫腙包覆钛酸锶钡粉体对水中镉的吸附性能

用草酸盐化学共沉淀法合成钛酸锶钡粉体，用双硫腙对该粉体表面进行包覆修饰，制成新型有机包覆吸附剂。用傅里叶变换红外光谱对包覆粉体进行了表征；以火焰原子吸收为检测手段，研究了该吸附剂对水中Cd2+ 的吸附性能，考察了洗脱条件；通过红外光谱，初步探讨了包覆和吸附作用机理。结果表明，双硫腙以氢键作用牢固地包覆于钛酸锶钡粉体上；该包覆粉体对水中的Cd2+具有较高的选择性吸附能力，其吸附量受介质的pH值影响，当pH值小于3时，该吸附剂对水中的Cd2+几乎不吸附，当pH值大于6时，吸附量达到最大；常温下，20 min内吸附达到平衡；吸附在双硫腙包覆钛酸锶钡粉体上的Cd2+,可用5% EDTA溶液完全洗脱。建立了吸附富集，火焰原子吸收法测定水中Cd2+的新方法，方法检出限为0.2 μg·L-1,相对标准偏差为2.9%。应用于自来水和地表水中Cd2+的测定，结果满意。

Study on the Adsorption Capability of Barium-Strontium Titanate Powder Coated with Dithizone for Cadmium Ion in Water

Barium-strontium titanate (BST) powder was prepared by using oxalate coprecipitate method, and the surface of barium-strontium titanate (BST) powder was modified by coating with dithizone, gaining a new sort of sorbent. FTIR analysis was used for characterizing the surface modification. By means of determination with flame atomic absorption spectrometry (FAAS), the adsorption capability of cadmium on the coating BST powder was investigated, and the condition of elution was observed; studies of coating and adsorption mechanism were also performed. The results showed that dithizone coated on the BST powder throngh hydrogen bonding between the hydroxyl groups and oxygen atoms on surface of the BST and dithizone. The cadmium ion in water could be adsorbed quantitively on dithizone coated BST when the pH was 6.0. At room temperature, the adsorption equilibrium could be obtained in 20 min. 5% EDTA was sufficient for complete elution. A new method for the determination of trace cadmium based on dithizone coated BST separation/ preconcentration and FAAS determination was proposed. The detection limit of this method for cadmium ion was 0.2 microg x L(-1), and the RSD was 2.9%. The method has been applied to the determination of trace cadmium ion in water samples with satisfactory results.