ABSTRACT
Herein, a synthetic strategy for a rough microsphere Cr(VI)-adsorbent via the reaction of tannic acid (TA) and 1,6-hexanediamine (HA) and using polyethylene glycol (PEG) as surface modifier was presented. This adsorbent was characterized by a Fourier Transform Infrared spectrometer (FTIR), thermogravimetic analysis (TGA), X-ray photoelectron spectroscopy (XPS), etc. Certain factors, including contact time, PEG@poly(tannin-1,6-hexanediamine) (PEG@PTHA) dosage, initial concentration, and experimental temperature affecting the Cr(VI) adsorption performance of adsorbent were explored. PEG@PTHA can adsorb Cr and the Cr(VI) was reduced up to Cr(III) due to the existence of phenolic hydroxyl groups. Its adsorption capacity can reach up to 300 mg/g within 10 min and approximately 100% removal percentage below the initial concentration of 100 mg/L. Its behavior matched well with the Langmuir isotherm model and pseudo-second-order kinetic model. A PEG@PTHA adsorbent with maximum adsorption capacity (450 mg/g) has great prospects in Cr(VI)-sewage treatment.
ABSTRACT
The development of zinc-ion storage cathode materials for aqueous zinc-ion batteries (AZIBs) is a necessary step for the construction of large-scale electrochemical energy conversion and storage devices. Iron-doped alpha-manganese dioxide (α-MnO2) nanocomposites were achieved in this study via pre-intercalation of Fe3+ during the formation of α-MnO2 crystals. A polypyrrole (PPy) granular layer was fabricated on the surface of α-MnO2 using acid-catalyzed polymerization of pyrroles. The pre-intercalation of Fe3+ effectively enlarges the lattice spacing of α-MnO2 and consequently decreases the hindrance for Zn2+ insertion/extraction in the iron-doped α-MnO2 coated by PPy (Fe/α-MnO2@PPy) composite. Meanwhile, the PPy buffer layer can ameliorate electron and ion conductivity and prevent dissolution of α-MnO2during the charge/discharge process. This unique structure makes the Fe/α-MnO2@PPy composite an efficient zinc-ion storage cathode for AZIBs. The targeted Fe/α-MnO2@PPy cathode achieves superior performance with reversible specific capacity (270 mA h g-1 at 100 mA g-1) and exhibits highdiffusioncoefficientof 10-10-10-14 cm-2 s-1. Therefore, a feasible approach is implemented on advanced electrode materials using in AZIBs for practical applications.
ABSTRACT
Three photosensitive tert-butylcalix[n]arene (TBC[n], n = 4, 6, 8)-protected titanium-oxo clusters (TOCs), formulated as [Ti4(µ3-O)2(TBC[4])2(OiPr)4(DEF)2]·DEF (1, TBC[4]-Ti4, DEF = N,N-diethylformamide), [Ti4(µ4-O)TBC[6](OCH3)9]·H2O (2, TBC[6]-Ti4), and [Ti4(µ3-O)2(OiPr)4TBC[8](DEF)2]·DEF (3, TBC[8]-Ti4), were successfully synthesized and characterized. Because of the generation of charge transfer from TBC[n] to the TiO core, the three TBC[n]-decorated TOCs show a broadened visible-light absorption and narrowed optical band gap based on the UV-visible spectra and density functional theory calculations. The corresponding photosensitive electrodes prepared using these three TOCs exhibit stable photocurrent responses. Furthermore, their photocatalytic performances for hydrogen evolution and methylene blue degradation were evaluated, and all of the materials display excellent photocatalytic activity and stability. The calixarene-Ti coordination is therefore an effective strategy to enlarge the visible-light absorption band of Ti-O materials and improve their photoelectric/photocatalytic performances.
