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Zhang, Hailin

Publications and source records attributed to Zhang, Hailin.

10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Bioleaching ion-unexchangeable rare earth in ion-adsorption type rare earth waste tailing

Ion-adsorption type rare earth ores (IREO) in China serve as the primary source of medium and heavy rare earth globally. With the rapidly growing demand for rare earth elements (REEs) and the dwindling supply of premium IREO, enhancing the recovery of REEs, especially the ion-unexchangeable REEs with ultra-low content and ambiguous speciation from IREO or its tailing, has become a critical trend and challenge. Here, this study identified the occurrences of ion-unexchangeable REEs, primarily detected in Fe-enriched minerals, xenotime, and monazite of IREO using TESCAN integrated mineral analyzer (TIMA) and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) analysis. To extract these elusive REEs, a bioleaching technique utilizing Aspergillus niger (A. niger) metabolites was proposed, achieving a leaching yield of 31.4 wt%. Complementary sequential chemical extraction methods (SCEM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations further elucidate the underlying mechanism, involving the carboxylic acid produced by the metabolic process of microbes that dissolves goethite by disrupting Fe—O bonds and liberating REEs, which complexed with carboxylate (R—COO—), to promote further dissolution. This work offers insight into enhancing the recovery of ion-unexchangeable REEs from IREO or its tailing, paving the way for sustainable and efficient rare earth mining practices.

42 ENGINEERING↗
DOE OSTI2023

Ultra-low concentration terbium (Tb) adsorption on garlic peels biosorbent and its application for $\mathrm{Nd}$-$\mathrm{Fe}$-$\mathrm{B}$ scraps recovery

Motivated by the strategic value of middle-heavy rare earth elements (MHREEs), we proposed a bio-adsorption method to recover ultra-low concentration terbium (Tb(Ⅲ)) from industrial wastewater that originated from the Nd-Fe-B scraps recovery process. It could be found that Tb(Ⅲ) ions as low as 5.34 ng·mL -1 (ppb) could be adsorbed onto Ca(Ⅱ)-modified garlic peels (Ca-GP) within 10 min with the adsorption efficiency of 99.2% at pH 3.5. The adsorption behavior of Tb(Ⅲ) onto Ca-GP conformed the Langmuir isotherm model and pseudo-second-order kinetic model. Attenuated total reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and density-functional theory (DFT) calculations results showed that Tb(Ⅲ) ions could be ion-exchanged with cations in Ca-GP such as Ca(Ⅱ) and -COOH. In application, column experiment results showed that the maximum bed adsorption capacity for Tb, praseodymium (Pr), neodymium (Nd), dysprosium (Dy), and Total rare earth elements (REEs) ions calculated by the Thomas model was 0.06, 3.50, 9.65, 7.34, and 27.37 µg·g -1 , respectively, with the initial concentration of 0.37 ng·mL -1 Tb, 20 ng·mL -1 Pr, 44 ng·mL -1 Nd, 67 ng·mL -1 Dy and 170 ng·mL -1 total REEs ions of actual solutions (below the solubility of rare-earth hydroxide). Here this manuscript thus provided a novel cost-effective and efficient approach to the enrichment and recovery of MHREEs from ultra-low concentration REEs ions-containing solutions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Crystallization and Phase Transformations of Aluminum (Oxy)hydroxide Polymorphs in Caustic Aqueous Solution

Gibbsite, bayerite, and boehmite are important aluminum (oxy)hydroxide minerals in nature and have been widely deployed in various industrial applications. They are also major components in caustic nuclear wastes stored at various U.S. locations. Knowledge of their crystallization and phase transformation processes contributes to understanding their occurrence and could help optimize waste treatment processes. While it has been reported that partial conversion of bayerite and gibbsite to boehmite occurs in basic solutions at elevated temperatures, systematic studies of factors affecting the phase transformation as well as the underlying reaction mechanisms are non-existent, particularly in highly alkaline solutions. We explored the effects of sodium hydroxide concentrations (0.1~3 M), reaction temperature (60~100 ?) and aluminum concentrations (0.1~1 M) on the crystallization and transformation of these aluminum (oxy)hydroxides. Detailed structural and morphological characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) spectrometry revealed that these processes depend largely on the reaction temperature and the Al/OH- ratio. When 1 = Al/OH- = 2.5, the reactions favor formation of high crystallinity precipitates, whereas at Al/OH- ratio ? 2.5 precipitation ceases unless the Al concentration is higher than 1 M. We identified pseudoboehmite, bayerite and gibbsite as intermediate phases to bayerite, gibbsite and boehmite, respectively, all of which transform via dissolution-reprecipitation. Gibbsite transforms to boehmite in both acidic and weak caustic environments at temperatures above 80 oC. However, a ‘bar-shaped’ gibbsite morphology dominates in highly caustic environments (3 M NaOH). The findings enable a robust basis for selection of various solid phases by tuning the reaction conditions.

aluminum (oxy)hydroxide polymorphs, crystallizatio↗
DOE OSTI2020

The role of surface hydroxyls on the radiolysis of gibbsite and boehmite nanoplatelets

Understanding mechanistic pathways to radiolytic hydrogen generation by metal oxyhydroxide nanomaterials is challenging because of the difficulties of distinguishing key locations of OH bond scission, from structural interiors to hydroxylated surfaces to physi-sorbed water molecules. In this work we exploited the interface-selectivity of vibrational sum frequency generation (VSFG) to isolate surface versus bulk hydroxyl groups for gibbsite and boehmite nanoplatelets before and after 60 Co irradiation at dose levels of approximately 7.0 and 29.6 Mrad. While high-resolution microscopy revealed no effect on particle bulk and surface structures, VSFG results clearly indicated up to 83% and 94% radiation-induced surface OH bond scission for gibbsite and boehmite, respectively, a substantially higher proportion than observed for interior OH groups by IR and Raman spectroscopy. Electron paramagnetic spectroscopy revealed that the major radiolysis products bound in the mineral structures are trapped electrons, O , O 2 – and possibly F-centers in gibbsite, and H , O and O 3 – in boehmite, which persist on the time frame of several months. The entrapped radiolysis products appear to be highly stable, enduring re-hydration of particle surfaces, and likely reflect a permanent adjustment in the thermodynamic stabilities of these nanomaterials.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution

Incorporation of relatively minor impurity metals onto metal (oxy)hydroxides can strongly impact solubility. In complex highly alkaline multicomponent tank waste such as that at the Hanford Nuclear Reservation, tests indicate that the surface area-normalized dissolution rate of boehmite ($γ$-AlOOH) nanomaterials is at least an order of magnitude lower than that predicted for the pure phase. In this work we examine the dissolution kinetics of boehmite coated by adsorbed Cr(III), which adheres at saturation coverages as sparse chemisorbed monolayer clusters. Using 40 nm boehmite nanoplates as a model system, temperature-dependent dissolution rates of pure versus Cr(III)-adsorbed boehmite showed that the initial rate for the latter is consistently several times lower, with an apparent activation energy 16 kJ·mol -1 higher. Although the surface coverage is only around 50%, solution analytics coupled to multimethod solids characterization reveals a phyicochemical armoring effect by adsorbed Cr(III) that substantially reduces the number of dissolution-active sites on particle surfaces. Such findings could help improve kinetics models of boehmite and/or metal ion adsorbed boehmite nanomaterials, ultimately providing a stronger foundation for the development of more robust complex radioactive liquid waste processing strategies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Surface Hydration and Hydroxyl Configurations of Gibbsite and Boehmite Nanoplates

Discontinuation of the bulk structure at the interface between metal oxide particles and water leads to altered bonding characteristics and unique facet-dependent molecular environments. Surface hydration and consequent hydroxylation adds further complexity to the interface, details that for metal (oxy)hydroxides are especially difficult to isolate from the background signal of bulk structural hydroxyls. Here we probe for the first time the hydroxylation and hydration structures on basal surfaces of gibbsite (?-Al(OH)3) and boehmite (?-AlOOH) nanoplates at ambient conditions, using the interface-sensitive technique vibrational sum frequency generation spectroscopy (VSFG). Hydroxyl stretching modes at the interfaces with adsorbed water layers compared directly to Raman and infrared bulk modes show that while gibbsite surface frequencies were sharp and nearly identical to those in the bulk, boehmite surface hydroxyls displayed a very different broad spectrum of states. Ab initio molecular dynamics simulations of both basal surfaces with and without hydration waters reveal that gibbsite surface hydroxyls interact only weakly with overlying hydration waters remaining essentially unperturbed, whereasthose on boehmite can interact more strongly facilitated by higher configurational degrees of freedom at the interface. The findings clearly unveil substantial differences in the hydrated interfacial dynamics of these two otherwise similar materials, with implications for their interfacial chemistry and wettability.

Sassi, Michel JPC↗
DOE OSTI2020

Two-step route to size and shape controlled gibbsite nanoplates and the crystal growth mechanism

Mastery of gibbsite (α-Al(OH) 3 ) nucleation and crystal growth is significant in fundamental aluminum chemistry and also beneficial for industrial applications and the remediation of nuclear waste. Herein, we developed an additive-free two-step route to size and morphology controlled synthesis of gibbsite nanoplates. Independent temperature manipulation of nucleation and crystal growth regimes was used to control the efficacy and yield of the process, producing gibbsite nanoplates with tunable morphologies and sizes. We achieve morphologies ranging from hexagon, pseudo hexagon, truncated triangle to rhombic, and average basal plane diameters from 120 to 850 nm, with thicknesses between 8 and 45 nm. Analysis of gibbsite structure, size and morphology with techniques including powder X-ray diffraction (p-XRD), 27 Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), scanning electron microscopy (SEM), and atomic force microscopy (AFM) provided key details on the nucleation and crystal growth mechanisms. The results indicate the temperature of the nucleation aging step is the most important factor controlling the final particle size. Particularly small nanoplates were obtained with a low nucleation aging temperature followed by high crystal growth temperature, suggesting that gibbsite growth can be approximated via a LaMer-type burst nucleation and crystal growth mechanism. Scalability was demonstrated by triplicate of 2 L experiments which prepared gibbsite nanoplates of ~200 nm size and with an average yield of ~55% after 84 h. Compared to existing techniques, this improved two-step route is cheaper, more efficient and environmentally friendly.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗