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In this study, a modified synthetic zeolite adsorbent was synthesized by the hydrothermal method using coal fly ash as the main raw material, and the enhanced phosphorus adsorption properties from aqueous solutions were then evaluated. The modification parameters were specifically studied and optimized. Moreover, the effects of initial phosphorus concentration, adsorption time, and pH value on phosphorus absorption were also investigated. The adsorbent was characterized by the energy-dispersive spectrometer analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. Furthermore, the phosphorus adsorption properties of the zeolite adsorbent were preliminarily discussed through the perspectives of isothermal adsorption experiments, adsorption kinetics experiments, and adsorption thermodynamics calculations. The results show that the lanthanum ions were physically loaded on the surface and micropores of the adsorbent after modification, which helps to enhance the adsorption effect of phosphorus components from the aqueous solution. The phosphorus removal rate has been increased by about 65%. The adsorption process better fitted the Langmuir and Elovich equations. The theoretical calculation and analysis of adsorption thermodynamics showed that the adsorption and removal of phosphorus in water happens spontaneously.

Using synthetic zeolite from fly ash to treat high concentration phosphorus wastewater does not only improve the utilization of fly ash as solid waste but also reduce the environmental pressure caused by eutrophication. A synthetic zeolite was prepared from coal fly ash by one-step hydrothermal synthesis and applied for phosphorus adsorption from industrial wastewater (∼8,000 mg-P/L), and its adsorption characteristics and performance were studied. The results indicated that the product was a well-crystallized Na-P1 zeolite with typical morphology of plate- and rod-shaped crystals. Compared with the original fly ash, the specific surface area and average pore volume of the synthetic zeolite were nine and six times larger than the fly ash, reaching 43.817 m2/g and 0.122 cm3/g. The results from phosphorus adsorption onto the synthetic zeolite showed that the synthetic zeolite had good phosphorus adsorption properties. The adsorption process highly conformed to the pseudo-second-order kinetic model with the regression coefficient R 2 of 0.998. Phosphorus adsorption on the synthetic zeolite was fitted to the Langmuir monolayer adsorption model, and the regression coefficient R 2 was 0.989. The maximum phosphorus adsorption capacity was 84.4 mg-P/g-zeolite.

Although phosphate rock has been considered as a potential new rare earth elements (REEs) resource, the recovery of REEs from phosphate rock is impeded by technical challenges and cost issues. This study investigated the effects of operation conditions on the leaching efficiencies of REEs and phosphorus from Zhijin phosphate ore, a large phosphate deposit in China. The leaching process overtime was also studied by chemical analysis, scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD). The results indicated that the REEs from Zhijin phosphate ore were mainly present in fluorapatite and dolomite, and REEs had similar trends of leaching efficiency to those of phosphorus and magnesium. Under the conditions of 25 wt% phosphoric acid concentration in the initial pulp, a weight ratio of liquid to solid of 12 mL/g, a temperature of 60°C, an agitation speed of 220 rpm, and leaching time of 120 min, REEs and phosphorus leaching efficiencies of 97.8% and 99.7% were obtained. Most parts of dissoluble substances were decomposed within 30 min. Chemical analysis, SEM-EDS, and XRD results indicated that leaching efficiencies of minerals in Zhijin phosphate ore increased following the order: quartz, aluminosilicate, pyrite, fluorapatite, dolomite, and calcite.

Developing cost-effective, active, and durable electrocatalysts is one of the most important issues for the commercialization of fuel cells. Ultrathin Pt-Mo-Ni nanowires (NWs) with a diameter of ~2.5 nm and lengths of up to several micrometers were synthesized via a H2-assisted solution route (HASR). This catalyst was designed on the basis of the following three points: (i) ultrathin NWs with high numbers of surface atoms can increase the atomic efficiency of Pt and thus decrease the catalyst cost; (ii) the incorporation of Ni can isolate Pt atoms on the surface and produce surface defects, leading to high catalytic activity (the unique structure and superior activity were confirmed by spherical aberration-corrected electron microscopy measurements and ethanol oxidation tests, respectively); and (iii) the incorporation of Mo can stabilize both Ni and Pt atoms, leading to high catalytic stability, which was confirmed by experiments and density functional theory calculations. Furthermore, the developed HASR strategy can be extended to synthesize a series of Pt-Mo-M (M = Fe, Co, Mn, Ru, etc.) NWs. These multimetallic NWs would open up new opportunities for practical fuel cell applications.

The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

The effects of particle size on the apparent kinetics of carbothermal reduction process of phosphate rock were studied by non-isothermal thermogravimetric analyses. Phosphate rock of various particle size was reacted with coke and silica under high purity argon atmosphere. The apparent kinetic model and parameters of carbothermal reduction reaction of phosphate rock with different particle sizes were derived by combination of model-free (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Tang, Starink) and model-fitting (Coats-Redfern, Master-plots) methods. The results showed that the obtained apparent activation energy of reaction reduces from 371.74 kJ/mol to 321.11 kJ/mol as the particle size of phosphate rock decreasing from 100–150 μm to 38–48 μm. The reaction apparent kinetics was found to follow shrinking-core model and the conversion degree function equation is G(α)=1−(1−α)12G\left( \alpha \right) = 1 - {\left( {1 - \alpha } \right)^{{1 \over 2}}} (α is conversion degree and G(α) is integral form of conversion degree function).