Xiaoyan Zhao,Yongcheng Zhou,Hua Guo,Yuqi Zhai,Xianrui Zou,Donghui Wang
Titanium dioxide (TiO 2 ) has received widespread attention as high stability, low toxicity and costless photocatalyst , but it only exhibits photocatalytic activity under ultraviolet (UV) light. To improve TiO 2 photocatalytic efficiency, Bio-CaCO 3 /WO 3 /TiO 2 /(Ca,Y)F 2 :Tm,Yb was prepared. TiO 2 was combined with upconversion materials, coupled with WO 3 and loaded on oyster shell powder (Bio-CaCO 3 ), which showed that the prepared photocatalyst effectively reduce the band gap of TiO 2 , expand the photoreaction range of the material and avoid agglomeration, thus improving its photocatalytic efficiency and antibacterial efficiency. The photocatalytic degradation efficiency of Bio-CaCO 3 /WO 3 /TiO 2 /(Ca,Y)F 2 :Tm,Yb (50 mg) was 24.32% higher than that of TiO 2 /(Ca,Y)F 2 :Tm,Yb in 90 min. And its antibacterial rates against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) were enhanced by 38.68% and 25.89% compared to TiO 2 /(Ca,Y)F 2 :Tm,Yb, respectively.
Yan Yi,Yang Shuai,Jiang Feng,Luo Yuwei,Gao Hejun,Liao Yunwen
The sheet-like adsorbent of the eggshell wastes was prepared by the thermal hydrolysis method. The structure of the adsorbent was characterized by scanning electron microscope, Brunauer-Emmett-Teller, X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectrometer. The adsorption capacity was investigated in a Pb 2+ solution. The effects of initial pH, salt concentration, contact time, and adsorbate concentration on the adsorption of lead ions were investigated in detail. The morphology of the adsorbent was sheet-like microspheres. Zinc selenide/zinc oxide could be uniformly loaded onto the eggshell waste surface, which could effectively enhance the specific surface area of the eggshell wastes. The adsorption kinetics and isotherm followed the pseudo-second-order and Langmuir–Freundlich isotherm model, respectively. The synthesized adsorbent showed a maximum lead adsorption capacity of 1,428.78 mg/g at room temperature. Ion-exchange was the main adsorption mechanism.
Huiyan Xiong,Jiemin Chen,Tingting Zhang,Wenzhong Wang,Chengcai Huang,Yuling Zhu,Baowei Hu
In this investigation, the magnetic bio-CaCO 3 were synthesized and elimination of uranium and europium from aqueous solutions. The prepared magnetic composite underwent a series of characterization analyses, such as Transmission electron microscope (TEM), Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), which prove that the magnetic particles are successfully modified on bio-CaCO 3. Surprisingly, it was found that coating the bio-CaCO 3 with Fe 3 O 4 not only increased the distance between the calcium carbonate nanosheets but also ensured the presence of Fe O active groups on the bio-CaCO 3 surface. The sorption of U(VI)/Eu(III) on the magnetic bio-CaCO 3 as a function of the pH, adsorbent dose, shaking time, co-existing ions, and the temperature was investigated using batch experiments. The effect of pH was investigated showing optimum sorption at pH 5 for U(VI) and Eu(III). The adsorption kinetics is relatively fast and can reach equilibrium in 60 to 90 min, and the pseudo-second-order rate equation preferentially fits the kinetic distribution, suggesting chemisorption was involved. The maximum adsorption amounts were 122.66 mg·g −1 for U(VI) and 130.62 mg·g −1 for Eu(III) at pH 5.0 and 298 K. The adsorption mechanism, which was evaluated with XRD, FTIR, SEM-EDS, and XPS, demonstrated that the functional groups (O H, -NH 2 , CO 3 2− and O Fe) and the increased hierarchical distances were primarily responsible for the improved adsorption ability. This paper highlights magnetic bio-CaCO 3 as potential, eco-friendly and ultrahigh-efficiency materials for uranium and europium pollution cleanup.
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