螯合型聚氨酯微粒的制备及对Hg(Ⅱ)吸附行为

Preparation and Adsorption Behavior of Chelated Polyurethane Particles of Mercury Ions

以二苯基甲烷二异氰酸酯(MDI)、三羟甲基丙烷(TMP)为原料,在温和条件下合成了具有异氰酸根的聚氨酯中间体(PU),由其表面端基—NCO和含有—NH_(2)、—SH活性基团的螯合剂进行加成反应,制备得到了螯合型聚氨酯微粒材料。以吸附量、吸附率为指标对螯合剂种类及用量进行了优化,采用IR、XRD及SEM对其结构进行表征,探究了氨基改性聚氨酯吸附剂对水中Hg(Ⅱ)的吸附性能。结果表明,在螯合剂三聚氰胺为1 mmol制备的螯合型聚氨酯微粒(PU-MEAM),在常温、pH值为4、时间为60min、初始浓度为100mg·L^(-1)的Hg(Ⅱ)吸附量达到48.34mg·g^(-1),吸附动力学符合准二级动力学模型,属于化学吸附,吸附热力学符合Langmuir模型描述的单分子层吸附,在Hg(Ⅱ)与Ca(Ⅱ)、Mg(Ⅱ)组成的混合体系中对Hg(Ⅱ)有较高的选择性,选择性系数分别达到14.82、7.75。

Using diphenylmethane diisocyanate(MDI)and trimethylol propane(TMP)as raw materials,polyurethane midbodys were synthesized under mild conditions.The surface end group—NCO and chelating agent containing—NH_(2),—SH active group were added to extend the chain reaction to prepare the chelating polyurethane adsorbent(PU-MEAM).The types and dosages of chelating agents were optimized with adsorption capacity and adsorption rateas the index,the structure was characterized by IR,XRD and SEM,the adsorption performance was investigated of the amino modified polyurethane adsorbent of Hg(Ⅱ)ions in water.The results showed that the adsorption capacity reached 48.34 mg·g^(-1) of PU-MEAM was better when the chelating agent melamine was 1 mmol,at normal temperature,pH value 4,time was 60 min and initial concentration was 100 mg·L^(-1),Adsorption kinetics conforms to the quasi-second-order kinetics model and belongs to chemical adsorption,Adsorption thermodynamics conforms to the Langmuir model of monolayer adsorption,In Hg(Ⅱ)and Ca(Ⅱ),Mg(Ⅱ)in the mixed system of Hg(Ⅱ)with high selectivity,respectively,selectivity coefficients were 14.82 and 7.75.