用新型的二氧化硅改性的热还原石墨烯为吸附剂采用固相萃取法和紫外可见分光光度法痕量测定环境水样中的铬vi含量教学材料.ppt

Trace determination of chromium(VI) in environmental water samples using innovative thermally reduced graphene (TRG) modified SiO2 adsorbent for solid phase extraction and UV–vis spectrophotometry
用新型的二氧化硅改性的热还原石墨烯为吸附剂采用固相萃取法和紫外可见分光光度法痕量测定环境水样中的铬(VI)含量
姓名:汤娟
专业:化学工程
In this work, we prepared a novel adsorbent by attaching TRG on silica-supported 3-aminopropyltriethoxysilane (SiO2-APTES)surface, and used for extraction of Cr (VI) in environmental water samples. The selectivity of the adsorbent toward the Cr (VI) species was improved by formation of a Cr (VI)-plex prior to the adsorption. Complex formation between Cr(VI) and DPC is an interesting reaction for spectrophotometric determination of Cr(VI). This reaction has high selectivity for Cr (VI) versus Cr (III). The adsorbent has surface characteristics of graphene and graphene oxide such as large contact surface area and high amounts of polar groups on the surface. These properties results in high water-dispersibility of the adsorbent and provide a rapid adsorption process. The detection of the extracted Cr (VI) was performed with UV–vis spectrophotometry. The violet Cr (VI)-plex exhibits a maximum absorption at 543 nm.
Experimental
Preparation of the adsorbent
At first, silica-supported 3-aminopropyltriethoxysilane (SiO2-APTES) was prepared based on the literature. A portion of GO() was added to 40 mL of distilled water and then, sonicated for 30min. Next, SiO2-APTES (20g) was placed in a beaker and the solution containing GO was added to it gradually (SiO2-APTES should not be dried in this step). Then, the mixture was heated up to 15˚C for 20min.
The precedure
At first, pH of 25mL of the sample solution containing Cr (VI)(10ng mL-1) was adjusted at by adding H2SO4( molL-1). Then, 150μL of DPC solution (10-2 mol L-1 in MeOH) was added to it to form the Cr (VI)-plex. After 5 min, of SDS (1% w/v) was added to the sample that, 20 mg of the adsorbent was transferred to t