Synthesis of high-crystallinity Zeolite A from rare earth tailings: Investigating adsorption performance on typical pollutants in rare earth mines

The ecological restoration of rare earth mines and the management of rare earth tailings have consistently posed global challenges, constraining the development of the rare earth industry. In this study, Zeolite A is efficiently prepared from the tailings of an ion-type rare earth mine in the southern Jiangxi Province of China. The resulting Zeolite A boasts exceptional qualities, including high crystallinity, a substantial specific surface area, and robust thermal stability. The optimum conditions for Zeolite synthesis are experimental determination and the adsorption properties of Zeolite A for typical pollutants (Cd2+, Cu2+, NH4+, PO43- and F-) in rare earth mines. The synthesised Zeolite A material is found to have strong adsorption properties. The adsorption mechanism is mainly cation exchange, and the priority of adsorption of pollutants is Cu2+> Cd2+ > NH4+ > PO43- > F-. Notably, the sodium Zeolite A material synthesized at room temperature can be effectively recycled multiple times. In summary, we propose a method to synthesise low cost and high adsorption zeolites using rare earth tailings. This will facilitate the reduction of rare earth tailings and the rehabilitation of rare earth mines. Our method has great potential as a rehabilitation technology for rare earth mines.

Optimization of alkali fusion process for determination of I-129 in solidified radwastes by neutron activation

This study determines the optimum temperature for the alkali fusion process used to effectively separate iodine from solidified radwaste attaining low-level ¹²⁹I by neutron activation. The alkali fusion temperature was adjusted to 120, 200, and 400 °C to approach the optimum conditions associated with a good statistical distribution of the measured ¹²⁹I data and high chemical recovery yield. Statistical analysis revealed that the optimum temperature of the alkali fusion process was 200 °C, displaying good central tendency and low variance of the measured ¹²⁹I data, and the respective chemical recovery yields were higher than other temperatures. The optimum fusion condition provides more reliable scaling factors (¹²⁹I/¹³⁷Cs) of radwaste.

Production of 191Pt from an iridium target by vertical beam irradiation and simultaneous alkali fusion

We have developed a new method for producing ¹⁹¹Pt from an iridium target. Alkali fusion of iridium was successfully performed using a vertical beam irradiation method and a mixed target of Ir and Na₂O₂, which resulted in easy dissolution of the irradiated iridium target. A trace amount of Pt^ⅣCl₆^2- was isolated from bulk Ir^ⅣCl₆^2- by solvent extraction and anion exchange chromatography. The production yield of ¹⁹¹Pt was 7.1 ± 0.4 (MBq/μA h, EOB) by proton irradiation at 30 MeV. The radioplatinum product (n.c.a.) was prepared at a radiochemical purity of 97% for Pt^ⅣCl₆^2-, and 95% for Pt^ⅡCl₄^2-, respectively.

Application of the Synthesized Activated Carbon-4A Zeolite Composite from Elutrilithe in Wastewater Treatment

The quartz abundant elutrilithe with several other elements from Pan zhihua, was taken as the main material to synthesize activated carbon-4A zeolite composite by hydrothermal crystallization after alkali fusion at 750 °C for 1 h under a flowing N2 atmosphere. Then the effect of alkali content and molar ratio of H2O versus Na2O on product was investigated, respectively. Finally, the activated carbon-4A zeolite composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry-differential scanning calorimetry (TG-DSC). The results showed that the crystallization product was activated carbon-4A zeolite composite with complete crystal form and the average particle size was about 1 μm. Moreover, the composite materials had well adsorption capacities to water, hexane and metal ions such as Cu2+, Ni2+, Zn2+ and Pb2+ analyzing by inductively coupled plasma atomic emission spectrometry (ICP).

Feasible conversion of solid waste bauxite tailings into highly crystalline 4A zeolite with valuable application

Bauxite tailings are a major type of solid wastes generated in the flotation process. The waste by-products caused significant environmental impact. To lessen this hazardous effect from poisonous mine tailings, a feasible and cost-effective solution was conceived and implemented. Our approach focused on reutilization of the bauxite tailings by converting it to 4A zeolite for reuse in diverse applications. Three steps were involved in the bauxite conversion: wet-chemistry, alkali fusion, and crystallization to remove impurities and to prepare porous 4A zeolite. It was found that the cubic 4A zeolite was single phase, in high purity, with high crystallinity and well-defined structure. Importantly, the 4A zeolite displayed maximum calcium ion exchange capacity averaged at 296 mg CaCO3/g, comparable to commercially-available zeolite (310 mg CaCO3/g) exchange capacity. Base on the optimal synthesis condition, the reaction yield of zeolite 4A from bauxite tailings achieved to about 38.43%, hence, this study will provide a new paradigm for remediation of bauxite tailings, further mitigating the environmental and health care concerns, particularly in the mainland of PR China.