功能接枝微粒PVI-SiO_2的制备及其吸附特性初探

Preparation of Functional Grafted Particles PVI-SiO_2 and Preliminary Study of Their Adsorption Characters

在偶联剂γ-(甲基丙烯酰氧)丙基三甲氧基硅烷的媒介作用下,在溶液聚合体系中,采用"接出"法将功能单体1-乙烯基咪唑(VI)接枝聚合于微米级硅胶微粒表面,制得了功能接枝微粒PVI-SiO2。采用红外光谱(FT-IR)、扫描电镜(SEM)及热失重分析(TGA)等方法对PVI-SiO2进行了表征;测定了接枝微粒的Zeta电位;考察研究了主要因素对接枝聚合的影响;初步探索了其对铬酸根负离子及重金属离子的吸附特性。研究结果表明:本接枝聚合体系亦呈现在固体微粒表面接枝聚合的一般规律,即已接枝到硅胶微粒表面的聚合物层,会对后续的接枝聚合产生阻隔作用;温度及引发剂用量等因素显著影响接枝度,在适宜条件下每100g PVI-SiO2接枝PVI 21.63g。在较大的pH范围内,接枝微粒的Zeta电位为较大的正值,在静电相互作用下,接枝微粒对铬酸根离子会产生很强的吸附作用,吸附量可高达120mg/g;凭借配位鳌合作用,接枝微粒对重金属离子具有强的吸附能力。

Vinylimidazole（VI） was graft-polymerized on micron-sized silica get particles in a manner of “graft from” in a solution polymerization system by right of the mediation of the coupling agent 3-metha- cryloxypropyl trimethoxysilane （MPS）, resulting in the functional grafted particles PVI SiO2. The grafted particles PVI-SiO2 were characterized by infrared spectrum （FT-IR）, scanning electron microscope （SEM） and thermogravimetric analysis （TGA）. The Zeta potential of the grafted particles was determined. The effects of the main factors on the graft polymerization were examined emphatically, and their adsorption character for chromate ion and heavy metal ions were preliminarily explored. The experimental results show that as the general rule of the graft polymerization on solid particles, for this graft system, the formed grafted polymer layer during the graft polymerization is a hindrance to the subsequent graft poly- merization, and the reaction temperature and the used amount of initiator affect the graft polymerization intensively. Under the suitable conditions, the grafting degree of PVI on the surfaces of the grafted parti- cles（100 g） can get up to 21.63 g. In a wider pH range, the Zeta potential of the grafted particles PVI-SiO2 is a greater positive value. By right of the strong electrostatic interaction, the grafted particles PVI SiO2 have strong adsorption ability towards chromate anions, and the adsorption capacity can reach 120 mg/g. By virtue of the coordination, the grafted particles PVI-SiO2 can produce strong adsorption ability for heavy metal ions.