Minerals
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2023
·Vol. 13
·期 12
·1530
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IF 2.5
Zongke Zhou,Quan Wan,Wenbin Yu,Xin Nie,Shuguang Yang,Shuqin Yang,Zonghua Qin
The enrichment process of rare earth elements in ion-adsorbed rare earth ores and bauxite is potentially related to the adsorption of rare earth elements by gibbsite. In this paper, lanthanum and yttrium were selected as surrogates of light rare earth elements and heavy rare earth elements, respectively. The effects of adsorption time, solution pH, and background electrolyte concentration on the adsorption of rare earth ions by gibbsite were investigated through batch adsorption experiments. The results showed that the adsorption of rare earth ions by gibbsite can approach equilibrium in 72 h. There is mainly electrostatic repulsion between gibbsite and rare earth ions at pH 4–7, and the adsorption efficiency increases with the increase in solution pH value and background electrolyte concentration. The adsorption process of rare earth ions by gibbsite is more consistent with the pseudo-second-order kinetic and Langmuir single-layer adsorption models. Moreover, based on the structural correlation between clay minerals and gibbsite, the causes for the differences in the adsorption behaviors of rare earth elements on the minerals are discussed. The results of this study help to understand the role of aluminum hydroxide in the migration and fate of rare earth elements in epigenetic environments.Keywords:gibbsite;rare earth element;adsorption;kinetics;thermodynamics
研究领域:
地质学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Jackson Nkoh Nkoh,Ke-wei Li,Yang-xiao-xiao Shi,Jiu-yu Li,Ren-kou Xu
Phosphorus (P) availability in highly weathered soils is significantly influenced by the contents of iron (Fe)/aluminum (Al) oxides, clay minerals, and organic matter. With the increasing interest in biofertilizers (e.g. chitosan), it is important to understand how they affect P adsorption profiles on colloids of weathered soils rich in Fe/Al oxides. Thus, the effect of chitosan on the adsorption of P to colloids of hematite, gibbsite , Oxisol , and Ultisol was studied through electrokinetic measurements, spectroscopic analysis , and adsorption edge/isotherm profiles. The presence of chitosan significantly improved the surface positive charge and the decreasing trend of surface positive charge was slower for chitosan-treated colloids compared to the control with increasing pH. At pH 5.0, all the colloids were positively charged, with the oxides containing more positve charges than the soil colloids. At this pH value, the surface coverage capacity of P was 99.1, 61.6, 50.5, and 37.5 mmol kg⁻ 1 for Oxisol, Ultisol, hematite, and gibbsite, respectively. This suggests that clay minerals in soil colloids were vital in enhancing P adsorption. In the presence of chitosan, the surface coverage capacity of P was increased by 111%, 173%, 647%, and 488% for Oxisol, Ultisol, gibbsite, and hematite, respectively. Drawing inferences from spectroscopic analysis, citric acid desorption profile, and zeta potential analysis, we suggest that chitosan (CH) enhanced P adsorption by promoting the formation of (i) citric acid “undisplaceable” inner-sphere P complexes such as [Colloid-OP- O -CH] and [Colloid-OP- N -CH] , (ii) citric acid “displaceable” outer-sphere P complexes such as {[Colloid- O -CH]-OP} and {[Colloid- N -CH]-OP} , and (iii) water “leachable or soluble” P complexes such as {[Colloid-CH] + PO 4 ³⁻} and {[Colloid-OP]⁻CH + } . Thus, applying chitosan as a biofertilizer (source of N) along with P in highly weathered soils could improve P availability while reducing P leaching .
研究领域:
土壤学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2019
·
IF 4.784
Xiujuan Zhao,Yangyang Luo,Peixin Tan,Mingxian Liu,Changren Zhou
A high-performance oil-water separation device that built by environment-friendly materials is a promising strategy to solve water pollution problem. In this study, we developed an oil-water separation system with chitin/halloysite nanotubes (C/HNTs) composites. C/HNTs were crosslinked by epichlorohydrin and freeze-dried, then a porous sponge was formed. The C/HNTs sponge was modified to be hydrophobic via immersing into bromohexadecane ethanol solution. The surface structure, mechanical properties, microstructure, oil absorption and oil-water separation ability of the C/HNTs sponge were investigated. The addition of HNTs significantly increased the compressive strength of chitin sponge without influence on porous structure . IR spectra indicated the successful coating of bromohexadecane on the C/HNTs sponge surface, which enabled the hydrophobicity and lipophilicity of this construct. The inside construct of the C/HNTs sponges were full of interconnected pores, and the pore size ranged from 250 to 500 μm. The absorption capability for various oil and grease were measured, including methylbenzene, sunflower seed oil , carbon dichloride, n-hexane, chloroform and acetone. It is found that the total amount of chloroform absorbed by a C/HNTs sponge was ~11.23 times of the sponge's weight, and the absorption for hexane was ~3.94 times of the sponge's weight. The sponge also exhibited an excellent oil-water separation ability with as high as 98.7% separation efficiency. All the results suggested that the chitin/HNTs sponges with improved mechanical property would have a great potential in oil-water separation.
研究领域:
材料科学
·
环境工程
·
高分子化学
·
纳米复合材料
·
分离技术
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Zhenhao Yang,Guihua Liu,Tiangui Qi,Qiusheng Zhou,Zhihong Peng,Leiting Shen,Yilin Wang,Xiaobin Li
The quality of alumina ceramics generally depends on alumina powder. High-density alumina ceramics were prepared from industrial coarse gibbsite. Near-spheric α-Al 2 O 3 with particles smaller than 500 nm was produced via the synergy of B and F from NH 4 BF 4 . The near-spheric α-Al 2 O 3 calcined at low temperature generated alumina ceramics with high density and low porosity. Meanwhile, the wet pretreatment yielded smaller particles with structural distortion and high microstrain and aluminum hydroxide, notably increasing the relative density of alumina ceramics. 99.18 % relative density, 0.017 % porosity, and 27.54 GPa Vickers hardness of alumina ceramics were achieved at 1650 °C for 2 h without additives and pressed sintering. In addition, the early stage of sintering of alumina green body followed particle boundary diffusion with reduced activation energy in the sintering process. The close packing of the spheric α-Al 2 O 3 , high microstrain of α-Al 2 O 3 , structural defects with considerable AlO 4 units calcined at low temperature, structural distortion in the alumina, and activated alumina on the α-Al 2 O 3 surface collectively promoted the densification of alumina ceramics, achieving remarkable hardness, high density, and tiny porosity.
研究领域:
材料科学
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陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Deping Xia,Yonggang Wang,Hui Liu,Hualin Lin,Sheng Han
The MoS 2 /AlOOH nanocomposites were prepared through a facile one-pot hydrothermal method and subsequently employed as lubricating oil additives to improve the tribological properties of PAO4 base oil. The structure, composition, morphology, tribological properties, and lubrication mechanism of the MoS 2 /AlOOH nanocomposites have been investigated. The results demonstrated that the in-situ assembly of MoS 2 on the surface of AlOOH change their microstructure, resulting in enhanced dispersion and a reduction in friction and wear. At 0.5 wt% concentrations of MoS 2 /AlOOH nanocomposites, the average COF, WSD, and wear volume were decreased by 50.47 %, 42.34 %, and 86.57 % compared to base oil, respectively. Moreover, the tribological behaviors of the PAO4 containing MoS 2 /AlOOH nanocomposites under various conditions were explored as well. Furthermore, based on the analysis of micromorphology and composition of wear surfaces, a synergistic lubrication mechanism for MoS 2 /AlOOH nanocomposites has been proposed, which involves the formation of a tribochemical film composed of Fe 2 O 3 , Fe 3 O 4 , MoS 2 , and Al 2 O 3 and demonstrates remarkable capabilities in reducing friction and wear. This research might provide new insight into enhancing the tribological properties of MoS 2 -based additives through the composite method and promote the application of MoS 2 /AlOOH nanocomposites as additives.
研究领域:
材料科学
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机械工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）