ABSTRACT
A new Schiff base modified MCM-41 molecular sieve(N-MCM-41)was synthesized via post-grafting method with 2-pyridine formaldehyde for efficient removal of lead ions(Pb2+)from aqueous solution.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform-infrared(FT-IR)spectroscopy,thermogravimetric analysis(TGA),and X-ray photoelectron spectroscopy(XPS)were employed to characterize the structure,morphology,surface functional groups and chemical states of N-MCM-41.Moreover,the adsorption behavior of Pb2+by N-MCM-41 was systematically studied.Batch adsorption studies revealed that N-MCM-41 showed the maximal adsorption capacity of 101.3 mg/g at 45℃and pH=5.5 under the initial Pb2+ concentration of 80 mg/L after 180 min adsorption.The adsorption process conformed to the Langmuir isotherm model and the pseudo-second-order kinetics model.The adsorption of Pb2+by N-MCM-41 was a spontaneous and endothermic process.Adsorption mechanism analyses suggested that functional groups on N-MCM-41 had strong coordination ability with Pb2+to improve the adsorption capacity.The synthesized N-MCM-41 adsorbent exhibited excellent reusability in five regeneration cycles.Overall,this study showed that the N-MCM-41 had good application prospect to remove Pb2+ from aqueous solution.
ABSTRACT
The rhizome of giant taro (Alocasia macrorrhiza (L.) Schott), which is a highly adaptable wild plant, is a traditional Chinese herbal medicine. In the current study, the antiproliferative constituents of giant taro were investigated and six new (1-6) and four known piperidine alkaloids (7-10) were isolated from its rhizomes. Their chemical structures and absolute configurations were elucidated using various spectroscopic methods and the Mosher ester method. The isolated alkaloids were screened for the antiproliferative activity through MTT assay. The results indicated that piperidine alkaloids exerted potential antiproliferative activity against HepG2, AGS and MCF-7 tumor cells. Further researches showed that compounds 3-5 dose-dependently decreased the colony formation rate and induced the apoptosis of AGS cells, while compound 4 induced AGS cell death via the proapoptotic pathway. This study demonstrates that the piperidine alkaloids isolated from giant taro exhibit significant antitumor activity, which provides phytochemical evidence for further development and utilization.