Preparation of monolayer amino-modified silica by aqueous phase and effect on adsorption of Pb2+
Monolayer amino-modified silica(SiO2-APTES and SiO2-AEAPTMS,used as adsorbents)was prepared by aqueous phase process by using silane coupling agents γ-aminopropyltriethoxysilane(APTES)and(β-aminoethyl)-γ-aminopropy-ltrimethoxysilane(AEAPTMS),which was charac-terized by using transmission electron microscopy,infrared spectroscopy analyzer,thermogravimetric differential thermal analyzer,elemental analyzer,and other instruments.The influence factors of Pb2+adsorption effect was investigated,and the optimal adsorption conditions were determined.The results showed that when the additive amount of coupling agent(mass fraction)was less than 15%,the monolayer amino modification of silica could be achieved.The maximum adsorption capacity of SiO2-APTES and SiO2-AEAPTMS for Pb2+reached 18.48,34.75 mg/g,respectively,under the opti-mized conditions of an initial Pb2+mass concentration of 200 mg/L,pH value of 6,and adsorption time of 60 min.The adsorption process conforms to the pseudo second-order kinetic model and Langmuir adsorption model,both of which were monolayer chemical adsorption process.The adsorption capaci-ty of Pb2+still exceeded 90%of the maximum ad-sorption capacity after the adsorbent repeated for 5 times,indicating the good cyclic performance.
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