磷酸功能化空心二氧化硅的制备及其对Cd^(2+)的吸附

Synthesis of Phosphonic Acid Functionalized Hollow Silica and Its Adsorption of Cd^(2+)

在水溶液中,分别以2-氰乙基三乙氧基硅烷(CTES)、3-脲丙基三甲氧基硅烷(UDPTMS)为内核与外壳前驱体,氨水为催化剂,通过一步法及官能团差异性刻蚀法合成了脲基功能化空心二氧化硅纳米球(UD-HSNs),并通过后磷酸化将功能化二氧化硅转化为磷酸基功能化空心二氧化硅纳米球(H_(2)O_(3)P-HSNs)。通过扫描电子显微镜(SEM)、场发射透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱仪和热重(TG)分析对所得微球的形貌、结构及性能进行了表征。研究结果表明,UD-HSNs与H_(2)O_(3)P-HSNs的粒径分布在450~650 nm范围内,壳层厚度在70~100 nm范围内,磷酸基团修饰前后纳米粒子的形貌和粒径变化不大。从比表面积和孔径分析可知,含脲基或磷酸基团的空心二氧化硅材料均具有一定的比表面积,FTIR、EDS、XPS和TG等表明,磷酸基团被成功地接枝到了二氧化硅材料上,改性后的材料含有一定量的P元素,其含量在5%左右。吸附实验表明,UD-HSNs与H_(2)O_(3)P-HSNs在120 min后逐渐能接近饱和吸附量,pH值为6左右、初始Cd^(2+)浓度在100~180 mg/L时两种材料具有较好的吸附性能,UD-HSNs的最大吸附量达152.63 mg/g,H_(2)O_(3)P-HSNs的最大吸附量达171.81 mg/g。在经过五次循环使用后,两种材料对Cd^(2+)的吸附性能仍然是第一次的65%~70%。

In an aqueous solution,2-cyanoethyltriethoxysilane(CTES)and 3-ureapropyltrimethoxysilane(UDPTMS)are used as the precursors of the core and the outer shell,and ammonia is used as the catalyst.Through a one-step method and differential etching of functional groups urea-based functionalized hollow silica nanospheres(UD-HSNs)were synthesized by the method,and the functionalized silica was converted into phosphoric acid-based functionalized hollow silica nanospheres(H_(2)O_(3)P-HSNs)by post-phosphorylation.Through scanning electron microscope(SEM),field emission transmission electron microscope(TEM),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectrometer and thermogravimetric(TG)analysis,the morphology,structure and the performance was characterized.The research results show that the particle size distribution of the urea-based and phosphoric acid-based functionalized hollow silica particles is in the range of 450—650 nm,and the shell thickness is in the range of 70—100 nm.The morphology and morphology of the nanoparticles before and after the phosphoric acid group modification the particle size changes little.From the analysis of specific surface area and pore size,hollow silica materials containing urea groups or phosphoric acid groups all have a certain specific surface area.FTIR,EDS,XPS and TG show that the phosphoric acid groups are successfully grafted to the silica in terms of materials,the modified material contains a certain amount of P element,the content of which is about 5%.The adsorption experiment shows that the two materials can gradually approach the saturated adsorption capacity after 120 min.When the pH value is about 6,the material has better adsorption performance when the initial Cd^(2+) concentration is 100—180 mg/L.The maximum adsorption capacity of UD-HSNs is 152.63 mg/g,and the maximum adsorption capacity of H_(2)O_(3)P-HSNs is 171.81 mg/g.After 5 cycles of use,the adsorption performance of Cd^(2+) is still 65%—70%of the first time.