A research on the cadmium ions adsorption of Sulfhydryl- and sulfo-functionalized UIO-66 with silica layer from water

In this study, adsorption behavior on UIO-66, UIO-66@mSi-SH and UIO-66@mSi-SO3H were investigated with a great emphasis on cadmium. The UIO-66@mSi-SH was synthesized by postsynthetic modification with silica layer, and sulfo-functionalized UIO-66 with silica layer (UIO-66@mSi-SO3H) was obtained from oxidizing UIO-66@mSi-SH with H2O2. All prepared adsorbents were characterized by FT-IR, SEM, XRD and BET. The BET value of UIO-66 can reach 1304.59 m(2) g(-1). To fit the adsorption behavior curve of Cd2+, the isothermal adsorption curve (Langmuir, Freundlich and D-R models) and kinetic model (Quasi first-order kinetic, Quasi second-order kinetic and Elovich model) were utilized. It shows that the basic mechanism of adsorption process was determined by R-2, AIC and other constants and the adsorption performance is shown as UIO-66@mSi-SO3H > UIO-66@mSi-SH > UIO-66. Langmuir and Elovich models showed better fitting results of UIO-66@mSi-SO3H adsorption process for Cd2+, and the R-2 values were 0.97471 and 0.97817 respectively. The theoretical maximum adsorption capacity of UIO-66@mSi-SO3H for Cd2+ is 409.96 mg g(-1) by Langmuir isothermal adsorption. The UIO-66@mSi-SO3H shows great adsorption capacity for Cd2+ with a surface area of 126.728 m(2) g(-1) and a pore volume of 0.102 cm(3) g(-1), which is approximately 93.73 % higher than UIO-66. Besides, more than 90 % adsorbents was able to be regenerated in shorter time after 5 cycles.

Automated summary

The adsorption behavior of UIO-66, UIO-66@mSi-SH, and UIO-66@mSi-SO3H towards cadmium was investigated, with UIO-66@mSi-SO3H showing the best adsorption performance. The adsorbent has a high adsorption capacity for Cd2+ and can be regenerated efficiently, making it a promising material for wastewater treatment.