Hydrotalcite-supported Pd-Cu catalyst for nitrate adsorption and reduction from water

Abstract

Hydrotalcite-supported Pd-Cu catalyst for nitrate adsorption and catalytic reduction from water is prepared by co-impregnation method and characterized by surface area (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectrum (XPS). The performance of adsorption and hydrogenation of nitrate was evaluated and compared with Al 2 O 3 , TiO 2 , and HZSM-supported Pd-Cu catalysts. The experimental results demonstrated that hydrotalcite-supported Pd-Cu catalyst exhibited a high surface area (185.3 m 2 /g) and mesopore structure (average pore diameter of 52.2 Å). The active metal clusters were homogeneously dispersed on the support, and the size of the most was less than 10 nm. Excellent adsorption for nitrate resulted from that nitrate ions were forced to enter the interlayer space when the calcined hydrotalcite regenerated layer structure in nitrate solution. The adsorption isotherm could be well described by the Langmuir model. The comparison between the adsorption and catalytic hydrogenation for nitrate using hydrogen indicated that nitrate reduction on hydrotalcite-supported Pd-Cu catalysts was a consecutive and dynamic adsorption and catalytic hydrogenation process. Compared with the Al 2 O 3 , TiO 2 , and HZSMsupported catalysts, hydrotalcite-supported Pd-Cu catalyst possessed higher catalytic activity and selectivity. The analysis on the dissolving of metals in the solution demonstrated that there was hydrolyzation on the surface of the hydrotalcite-supported Pd-Cu catalyst. However, the concentrations of dissolved metals in the solution were lower than the standard executed in China. The activity of the hydrotalcite-supported Pd-Cu catalyst for nitrate reduction kept steady after repeated use.

Adsorption and reduction of nitrate in water on hydrotalcite-supported Pd-Cu catalyst

“…In our previous study, the performance of adsorption and hydrogenation of nitrate on hydrotalcite-supported Pd-Cu catalyst prepared by impregnation has been compared intensively with different supports (Al 2 O 3 , TiO 2 , and molecular sieve (HZSM)) catalysts at the same Pd-Cu loading [25]. The results demonstrated that hydrotalcite-supported Pd-Cu catalyst processed higher catalytic activity and selectivity.…”

Development and application of innovative technologies for drinking water quality assurance in China

“…During the last ten years, some new methods/techniques used for the removal of nitrate ion from water have been investigated in China [61][62][63][64][65][66][67][68][69][70][71]. The methods include biological denitrification, bio-electrochemical denitrification and chemical denitrification.…”