Efficient and selective adsorption of V(V), pentavalent vanadium, from strategic polymetallic shale leaching solutions is crucial for resource utilization. However, the lack of a high-capacity adsorbent poses a significant challenge. Herein, we have successfully developed a novel composite adsorbent material by cross-linking orange peel biomass with aminated MXene , referred to as OPM . The incorporation of aminated MXene enhanced the availability of reactive groups within the material. The unique aerogel structure avoids the accumulation of MXene, thus improving the exposure of active sites. Furthermore, the positively charged surface of OPM enabled efficient adsorption of pentavalent vanadium ions . Experimental results showed that the adsorption of V(V) fitted well with the Langmuir adsorption isotherm model, and its adsorption rate was controlled by the pseudo-second-order kinetic mechanism. Remarkably, OPM exhibited a remarkable maximum adsorption capacity of 748.42 mg/g at pH=4. Even in the presence of interfering anions and cations, OPM maintains a high adsorption capacity for V(V).In the simulated wastewater adsorption experiment, the removal rate of V by the adsorbent exceeded 80 % After five cycles of adsorption, the material retains an adsorption capacity of more than 78 %. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy revealed that the adsorption mechanism of OPM on V(V) is attributed to the fact that OPM is protonated under acidic conditions and has strong electrostatic interactions with pentavalent vanadium anion, in which abundant hydroxyl and carboxyl groups can undergo ion-exchange reactions with vanadium anion. Meanwhile, the amino group reduces V(V) to V(IV) and forms a complex with the oxygen/nitrogen functional group. This study provides theoretical understanding and practical application for the synergistic adsorption of V(V) on aerogels prepared from MXene composite orange peel biomass.
In this study, we explored an effective and low-cost catalyst and its adsorption capacity and catalytic capacity for Methyl Orange Fenton oxidation degradation were investigated. The catalyst was directly prepared by reuse of magnetic iron oxide (Fe 3 O 4 ) after saturated adsorption of vanadium (V) from waste SCR (Selective Catalytic Reduction) catalyst. The obtained catalyst was characterized by FTIR, XPS and the results showed that vanadium (V) adsorption process of Fe 3 O 4 nanoparticles was non-redox reaction. The effects of pH, adsorption kinetics and equilibrium isotherms of adsorption were assessed. Adsorption of vanadium (V) ions by Fe 3 O 4 nanoparticles could be well described by the Sips isotherm model which controlled by the mixed surface reaction and diffusion (MSRDC) adsorption kinetic model. The results show that vanadium (V) was mainly adsorbed on external surface of the Fe 3 O 4 nanoparticles. The separation-recovering tungsten (VI) and vanadium (V) from waste SCR catalyst alkaline solution through pH adjustment was also investigated in this study. The results obtained from the experiments indicated that tungsten (VI) was selectively adsorbed from vanadium (V)/tungsten (VI) mixed solution in certain acidic condition by Fe 3 O 4 nanoparticle to realize their recovery. Tungsten (V) with some impurity can be obtained by releasing from adsorbent, which can be confirmed by ICP-AES. The Methyl Orange degradation catalytic performance illustrated that the catalyst could improve Fenton reaction effectively at pH = 3.0 compare to Fe 3 O 4 nanoparticles alone. Therefore, Fe 3 O 4 nanoparticle adsorbed vanadium (V) has a potential to be employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the decoloration efficiency of Methyl Orange.
A magnetic chitosan/TiO2 composite material (MCT) was developed. MCT was successfully synthesized by a one-pot method using chitosan, TiO2, and Fe3O4. The absorption equilibrium time of MCT was 40 min in absorbing vanadium(V), the optimal adsorption pH was 4, and the maximum adsorption capacity of vanadium(V) was 117.1 mg g−1. The spent MCT was applied to photocatalytic reactions for reutilization. The decolorization rates for the degradation of rhodamine B (RhB) by new and spent MCT were 86.4% and 94.3%, respectively. The new and spent MCT exhibited absorption bands at 397 and 455 nm, respectively, which showed that the spent MCT was red-shifted to the cyan light region. These results indicated that the forbidden band widths of the new and spent MCT were about 3.12 and 2.72 eV, respectively. The mechanism of the degradation reaction showed that the hydroxyl radicals as oxidants in the spent MCT mediated the photocatalytic degradation of RhB. In addition, the superoxide anion radical formation of hydroxyl radicals was the main reaction, and the hole generation of hydroxyl radicals was the subordinate reaction. The N-de-ethylated intermediates and organic acids were monitored by MS and HPLC.
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