Recyclable Ag/halloysite nanotubes/polyvinyl alcohol sponges for enhanced reduction of 4-nitrophenol
Recently, developing facile, cheap, and efficient nano‑silver catalysts for the reduction of waste 4-nitrophenol (4-NP) to useful 4-aminophenol (4-AP) has attracted more and more attention. In this study, a facile mechanical foaming method was used to fabricate Ag/halloysite nanotubes/polyvinyl alcohol sponges (Ag/Hal/PVA) for enhanced degradation of 4-NP. It included the preparation, morphology and composition characterization, and catalytic performance test of Ag/Hal/PVA. The morphology and composition of Ag/Hal/PVA were characterized by field emission scanning electron microscopy , Fourier transform infrared spectra , Raman spectra , X-ray photoelectron spectroscopy, thermo-gravimetric analysis, and XRD, respectively. BET and UV–vis spectrum measurements were used to test the adsorption and catalytic performance of Ag/Hal/PVA for 4-NP. The results showed that silver nanoparticles (AgNPs) were evenly distributed in the Hal/PVA sponge. Moreover, halloysite nanotubes (Hal) greatly improved the specific surface area and the loading capacity for AgNPs of the sponge due to the hollow tubular structure of Hal. The specific surface area of the Ag/Hal/PVA was about 1.62 m 2 /g. The obtained Ag/Hal/PVA exhibited a good catalytic activity and the apparent rate constant was 0.297 min −1 , and a good stability up to 5 cycles without a significant loss of its catalytic activity. This study provided a facile strategy for the development of cheap Ag/Hal/PVA sponges for high efficient reduction of 4-NP, which has potential application in the filed water treatment
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