Search

A reduced graphene oxide (RGO) supported Fe3O4-MnO2 nanocomposite (Fe3O4-MnO2@RGO) was successfully prepared for catalytic degradation of oxytetracycline (20 mg/L) by potassium persulfate (PS) and adsorption removal of mixture of Pb2+, Cu2+, and Cd2+ ions (each 0.2 mM) in the synchronous scenario. The removal efficiencies of oxytetracycline, Pb2+, Cu2+, and Cd2+ ions were observed as high as 100%, 99.9%, 99.8%, and 99.8%, respectively, under the conditions of [PS]0 = 4 mM, pH0 = 7.0, Fe3O4-MnO2@RGO dosage = 0.8 g/L, reaction time = 90 min. The ternary composite exhibited higher oxytetracycline degradation/mineralization efficiency, greater metal adsorption capacity (Cd2+ 104.1 mg/g, Pb2+ 206.8 mg/g, Cu2+ 70.2 mg/g), and better PS utilization (62.6%) than its unary and binary counterparts including RGO, Fe3O4, Fe3O4@RGO, and Fe3O4-MnO2. More importantly, the ternary composite had good magnetic recoverability and excellent reusability. Notably, Fe, Mn, and RGO could play a synergistic role in the improvement of pollutant removal. Quenching results indicate that surface bounded SO4•– was the major contributor to oxytetracycline decomposition, and the -OH groups on the composite surface shouldered a significant role in PS activation. The results indicate that the magnetic Fe3O4-MnO2@RGO nanocomposite has a good potential for removing organic-metal co-contaminants in waterbody. [ABSTRACT FROM AUTHOR]

In this study, a three‐dimensional nitrogen‐doped graphene (3DNG)‐Fe3+/poly(acrylic acid‐co‐N,N‐dimethylacrylamide) (3DNG‐Fe3+/P(AA‐co‐DMA)) hydrogel with strong flexibility and excellent self‐healing property was prepared. The 3DNG‐Fe3+/P(AA‐co‐DMA) hydrogel was characterized by Fourier transform infrared spectrometer (FT‐IR), scanning electron microscope (SEM). The specific surface area and pore size distribution of the 3DNG‐Fe3+/P(AA‐co‐DMA) hydrogel were measured by using Brunauer‐Emmett‐Teller (BET) method. The experimental results demonstrate that when 6 mol% FeCl3 was added, the breaking strain of Fe3+/P(AA‐co‐DMA) hydrogel reaches 1149 %, and the tensile strength reaches 689 kPa. Furthermore, the recovery degree of Fe3+/P(AA‐co‐DMA) hydrogel was almost 100 % after 24 h. The supercapacitors based on 3DNG‐Fe3+/P(AA‐co‐DMA) hydrogel have a specific capacitance value of 231.8 F g−1 at 1 A⋅g−1, and conductivity is 0.053 S⋅cm−1. When the power density is 5 kW kg−1, the energy density of the device is 38.7 Wh kg−1. [ABSTRACT FROM AUTHOR]

The use of heavy metal passivators to prevent vegetables from absorbing heavy metals is an important measure to control heavy metal-polluted vegetable fields and to ensure the safe production of vegetables. A pot experiment of planting three times in succession was conducted to study the effects of Bacillus megaterium N3 (N3), rice husk biochar (BC), sheep manure organic fertilizer (SM), strain N3 combined with biochar (BC+N3), and strain N3 combined with sheep manure (SM+N3) on Cd uptake and the functional stability of lettuce using a heavy metal passivator only at the first planting. The comprehensive applicability of the passivation materials was evaluated by the dynamic weighted comprehensive function. The results showed that when lettuce was planted for the first time, compared with the control, all the heavy metal passivators could significantly reduce (61.2%-81%) the Cd content in the edible part of the lettuce. However, in the third cultivation of lettuce, only SM+N3 could significantly reduce the Cd uptake by lettuce, which indicated that SM+N3 had the best functional stability. The dynamic weighted comprehensive function was used to evaluate the Cd content in the edible part of fresh lettuce, available Cd content in the soil, yield, and remediation cost. The results showed that the comprehensive applicability of SM+N3 was the best, followed by that of SM, BC+N3, and BC, and the comprehensive evaluation effect of strain N3 was the worst. The results of this study provide a theoretical basis and technical support for remediation of heavy metal-contaminated vegetable fields.