Low temperature and highly-efficient one-step decomposition of phosphogypsum via biochar by Fe3+/Co2+/Ni2+ unitary/ternary catalyst.

Phosphogypsum (PG), which has great environmental harm and restricts the sustainable development of phosphorus chemical industry, is a solid waste produced in phosphoric acid production. Thermal decomposition of PG is an extensive way to reutilization of resource, and the key point is to establish an appropriate decomposition path and catalyst system of PG. In the work, the strategy for low-temperature and highly-efficient decomposition of PG is established based on the thermodynamic analysis and the experimental research by metal ions to reduce the decomposition temperature. Meanwhile, SEM(Scanning Electron Microscope) is used to characterize the composition and morphology of PG in the various conditions, also the decomposition temperature is analyzed by TGA(Thermogravimetric Analysis). Then, the decomposition ratio via Fe3+/Co2+/Ni2+ unitary/ternary catalyst is obtained by precipitation method. Through kinetic analysis combined with XRF(X-ray Fluorescence Spectrometer) and EDX(Energy Dispersive X-Ray Spectroscopy) results, it is found that there is a reaction competition in the decomposition process by Fe3+/Co2+/Ni2+ ternary catalyst. Further the mechanism of catalytic system on PG is derived. The present work can be concluded that Fe3+/Co2+/Ni2+ can effectively reduce the decomposition temperature of PG, and the effect of ternary metal is more obvious than that of unitary metal. Finally, pomelo peel is used instead of coke to successfully decompose PG at low temperature by one step method. The establishment of low temperature decomposition system of PG has potential application in phosphorus chemical industry and is in line with sustainable development.

Novel 3D cross-shaped Zn/Co bimetallic zeolite imidazolate frameworks for simultaneous removal Cr(VI) and Congo Red.

The photocatalytic properties of Zn/Co zeolite imidazolate frameworks (ZIF-ZnCo) prepared by various Zn/Co ratio are of significantly diversity due to the morphology structure of the ZIF-ZnCo. Thereinto, the prepared ZIF-ZnCO-8:1 is excellent capability by virtue of its 3D cross-shaped structure. Spectral test results show that as-prepared novel 3D cross-shaped ZIF-ZnCo has a lower recombination rate of electron and hole pairs than the lamellar and dodecahedral, thus improving the photocatalytic ability. The photocatalytic ability of 3D cross-shaped ZIF-ZnCo was carefully investigated for removing mixed solution of Congo Red (CR) and Cr(VI). The photocatalytic reduction ability of 3D cross-shaped ZIF-ZnCo was 22% higher than ZIF-8 for Cr(VI). Meanwhile, CR was altogether removed at dark processing and Cr(VI) was removed 70% after dark processing 120 min and photocatalytic 240 min. Therefore, the high adsorption and photocatalytic capacity denote the potential application of 3D cross-shaped ZIF-ZnCo.

High-efficient removal of U(VI) from aqueous solution by self-assembly pomelo peel/palygorskite composite.

The efficient separation of low-concentration radionuclides by the eco-friendly adsorbent is a compelling requirement in the development of nuclear industry. Hence, a novel composite consisted of one-dimensional palygorskite (Pal) and three-dimensional pomelo peel (PP) is prepared by self-assembly approach (PP/Pal) and coupling agent approach (PP/KPal) for removing uranium (U(VI)) from aqueous solution. Moreover, the mass ratio (PP/Pal), adsorbent dosage, pH, contact time, temperature, and ionic strength are investigated. Two adsorption kinetic models and isotherm models are used to investigate the kinetic behaviors and adsorption capacity, respectively. The maximum adsorption capacities were 370.5 mg·g-1 on PP/Pal and 357.3 mg·g-1 on PP/KPal at pH 6.0, contact time 150 min and 25 °C. Meanwhile, the composite can be easily separated from water via a simple filtering. Furthermore, thermodynamic parameters indicate that adsorption is an endothermic and spontaneous process. And the surface complexation, ion exchange, and electrostatic attraction play a vital role. This work shows that the PP/Pal composite with high efficiency, low cost, and green has a further application in the treatment of wastewater containing U(VI).

Renewable biomass derived porous BCN nanosheets and their adsorption and photocatalytic activities for the decontamination of organic pollutants.

In this work, the preparation, characterization and removal capabilities of a novel biomass derived BC and its BCN nanocomposites are described. Possessing hierarchically porous structures, extremely large surface areas and special chemical bonds, porous BCN nanosheets have demonstrated advantages in terms of their adsorption and photocatalytic activities. The adsorption and photocatalytic activities of the as-prepared catalysts were evaluated by the degradation of RhB. The best results exhibited 97% and 95% decomposition of RhB which were obtained by using porous BCN-40 nanosheets within 120 min at 25 °C under UV light and visible light (>420 nm) irradiation respectively. The rate constant of the porous BCN-40 nanosheets for the degradation of RhB was more 16 times than that of pure h-BN. Besides, the porous BCN nanosheets showed remarkable cycling stability, maintaining a high photocatalytic activity up to 94% after 5 cycles. Furthermore, the degradation mechanisms of RhB and the photocatalytic mechanism have been explained in this paper.