查找使用阿拉丁产品的科研文献

Vaporthermal-driven rapid transformation of commercial gibbsite to rhombic boehmite flakes

Jia Luo,Yuqing Luo,Jun Tan,Hongsheng Che,Ting He,Jiugang Hu

The large-scale and controllable production of boehmite has attached much attention due to its extensive application in advanced energy and electronics industries. In this study, a facile vaporthermal (VPH) method was developed for the rapid fabrication of rhombic boehmite microflakes using low-cost commercial gibbsite particles. The evolution behaviors of gibbsite to boehmite under VPH and conventional hydrothermal (LPH) conditions were ex-situ monitored by XRD , Raman, and FT-IR techniques. The boehmite powders from VPH (V-boehmite) and LPH (L-boehmite) have similar crystal structure and bonding vibration information, whereas V-boehmite exhibits rhombic morphology and L-boehmite presents cubic morphology. Moreover, the formation time of boehmite can be shortened from 16 h of LPH to 6 h of VPH at 180 °C, which significantly contributes to its scalable production. These differences of V-boehmite are attributed to the direct contact between high-temperature saturated water steam and gibbsite, which can induce the rapid formation of rhombic boehmite microflakes through dissolution-recrystallization mechanism. Therefore, the vaporthermal technology has great potential for efficient, sustainable, and large-scale production of boehmite powders.

Adsorption Behaviors of Lanthanum (III) and Yttrium (III) Ions on Gibbsite

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

Adsorption of amino acids by montmorillonite and gibbsite: Adsorption isotherms and spectroscopic analysis

Jackson Nkoh Nkoh,Zhineng Hong,Hailong Lu,Jiuyu Li,Renkou Xu

The adsorption of glycine, cysteine and glutamic acid by gibbsite and montmorillonite was studied as a function of amino acid concentration and solution pH. Zeta potential measurements, X-ray diffraction (XRD), and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopic analysis were performed to deduce the mechanism(s) of adsorption and to observe changes in the basic structure of the minerals after interaction with amino acids. The ATR-FTIR analysis revealed that both NH 3 + and COO − groups of amino acids were very vital for interactions with the surface of gibbsite and montmorillonite. XRD analysis revealed that the formation of mineral-amino acid composites decreased the d 001 value of montmorillonite from 17.95 to 14.2 (glycine), 15.49 (cysteine), and 15.22 Å (glutamic acid). This observation suggests that amino acid adsorption induced structural stress on montmorillonite and expanded its interlayer space . Also, the adsorption of glycine and cysteine to gibbsite and montmorillonite increased their zeta potentials at pH 5.0 while glutamic acid decreased the zeta potentials. Thus, amino acid-induced increase/decrease in the surface positive/negative charge of the minerals indicates that chemical bonds were formed between glycine, cysteine, glutamic acid and the minerals. The findings of this study can serve as a reference for studies related to understanding the bonding interactions and distribution of different amino acids in soils.

Rationalize the High Performance of Lithium Sorbents Derived from Gibbsite Guided by Phase Chemistry

You Conglin,Li Dongdong,Fan Yanfei,Gao Dandan,Han Li,Zeng Dewen

Lithium aluminum layered double hydroxide chlorides (LADH-Cl) are the only industrial-level lithium sorbents. However, as an applied material, the composition-structure-property-performance relation is far from well constrained, leaving the manufacture and application of LADH-Cl lithium sorbents empirical rather than rational. Herein, we studied the phase evolution of gibbsite phase Al(OH) 3 in concentrated LiOH aqueous solution, suggesting the formation of lithiated lithium aluminum layered double hydroxide (LADH-OH) with Al:Li molar ratio 2. However, LADH-OH is not an active ingredient as a lithium sorbent. The neutralization of LADH-OH with a dilute HCl aqueous solution resulted in the formation of the active LADH-Cl phase. Unlike the traditional LADH-Cl phase (g-LADH-Cl) generated from direct LiCl intercalation of gibbsite, LADH-OH derived LADH-Cl (b-LADH-Cl) has a topological parent of bayerite instead of gibbsite. This is one of the most important roots for different performances. Another source for the different performance is very likely from variations of the particle size and morphology when the raw gibbsite reacted with LiCl or LiOH aqueous solution. Nevertheless, we found that the limiting-delithiation of b-LADH-Cl is still the same as g-LADH-Cl, that is only maximum 1/3 lithium can be delithiated from the LADH-Cl phase without any decomposition into gibbsite or bayerite. This concluded that b-LADH-Cl and g-LADH-Cl have the same reversible lithium “sorption–desorption” capacity, even through different lithium affinity and sorption kinetics. Also, notably, the “sorption–desorption” performance of the optimal sorbent is very sensitive to the properties of service brines. These results substantially enlarged our knowledge of the LADH-Cl phase and provided a demo of the rational manufacture of lithium sorbent. Graphical Abstract

Polymer grafted gibbsite nanoplatelets via direct initiator tethering and surface-initiated atom transfer radical polymerization

Ling Liu,Mingyuan Wu,Qingyun Wu,Jiuyi Liu,Jianjun Yang,Jianan Zhang

An efficient method for the preparation of polymer grafted gibbsite nanoplatelets (NPs) was proposed by direct preparation of initiator-tethered gibbsite (gibbsite-Br) NPs followed by surface-initiated atom transfer radical polymerization (SI-ATRP) to obtain gibbsite particle brushes. By adding portion of water-soluble solvent (e.g., alcohol), individual ATRP initiator-tethered gibbsite NPs were fabricated using 2-bromo-2-methylpropionic acid as a tetherable initiator avoiding the aggregation of gibbsite NPs which are ready for polymer grafting process. To verify the efficiency of the tethered initiator, various polymers grafted gibbsite NPs were fabricated by SI-ATRP. The results indicated that initiator anchored gibbsite NPs and various gibbsite-g-polymers (e.g., gibbsite-g-poly2-(dimethylamino) ethyl methacrylate, gibbsite-g-polyacrylonitrile, gibbsite-g-polymethyl methacrylate) were synthesized successfully. The thermal stabilities of gibbsite-g-polymer hybrid materials have been enhanced significantly. Compared with PMMA matrix, the fire-retardant behavior of gibbsite-g-polymethyl methacrylate was strengthened due to the incorporation of gibbsite NPs. This work proposed a versatile and convenient method for producing initiator-immobilized solid NPs and polymer grafts, which thereby enables promised properties of polymer hybrid materials depending on the orientation and interactions of particle brushes.

The mechanism for enhancing phosphate immobilization on colloids of oxisol, ultisol, hematite, and gibbsite by chitosan

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 .

Design and reinforcement mechanisms of the binary alumina ceramics with improved density derived from industrial gibbsite and boehmite

Jinquan Wen,Guihua Liu,Tiangui Qi,Nianzi Liu,Qiusheng Zhou,Jian Guo,Leiting Shen,Yilin Wang

The properties of starting aluminum hydroxide powder greatly determine the sintering activity and microstructure of final alumina ceramic. Combing the modified properties of industrial gibbsite and boehmite, binary alumina ceramics with high mechanical property were fabricated under ambient pressure without any additives. The enhanced sintering activity of binary alumina compacts is attributed to the high tetrahedral aluminum content stemmed from gibbsite due to pseudomorphic transition. The low α-Al 2 O 3 content and high microstrain in boehmite-derived α-Al 2 O 3 also facilitate the densification of binary alumina compacts. In addition, the sintering mechanism shifted from boundary diffusion to the combination of boundary and volume diffusion with the introduction of boehmite-derived alumina, leading to accelerated atoms migration and significant reduction of activation energy from 426   kJ/mol to 289   kJ/mol. The resultant rapid densification at low temperature prevented excessive grain growth at the late sintering and resulted in remarkable grains refining. Benefited from the collective effect of binary alumina packing, accelerated sintering kinetics and grain refinement strengthening, full dense in binary alumina ceramics with a 99.8% relative density, 0.02% apparent porosity, 25.88   GPa Vickers hardness and 4.41   MPa·m 1/2 fracture toughness was achieved at 1650℃ for 2   h. This study presented a facile efficient strategy to preparing high-quality binary alumina ceramics, also highlighting the differences in aluminum hydroxide precursor on the performance of alumina-bearing materials.

Structural defect and activated alumina of spheric α-Al2O3 improving alumina ceramics density from the industrial coarse gibbsite

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.

Effect of carbon and nitrogen mineralization of chitosan and its composites with hematite/gibbsite on soil acidification of an Ultisol induced by urea

Jackson Nkoh Nkoh,Peng Guan,Jiu-yu Li,Ren-kou Xu

Chitosan is a biodegradable polymer with a vast range of applications. Along with its metal composites, chitosan has been applied in the remediation of polluted soils as well as a biofertilizer . However, little attention has been given to the degradation of chitosan composites in soil and how they affect soil respiration rate and other physicochemical parameters. In this study, the degradation of chitosan and its composites with gibbsite and hematite in an acidic Ultisol and the effect on urea (200 mg N kg −1 ) transformation were investigated in a 70-d incubation experiment. The results showed that the change trends of soil pH, N forms, and CO 2 emissions were similar for chitosan and its composites when applied at rates <5 g C kg −1 . At a rate of 5 g C kg −1 , the C and N mineralization trends suggested that the chitosan-gibbsite composite was more stable in soil and this stability was owed to the formation of a new chemical bond (CH–N–Al-Gibb) as observed in the Fourier-transform infrared spectrum at 1644 cm −1 . The mineralization of the added materials significantly increased soil pH and decreased soil exchangeable acidity ( P  < 0.01). This played an important role in decreasing the amount of H + produced during urea transformation in the soil. The soil's initial pH was an important factor influencing C and N mineralization trends. For instance, increasing the initial soil pH significantly increased the nitrification rate and chitosan decomposition trend ( P  < 0.01) and thus, the contribution of chitosan and its composites to increase soil pH and inhibit soil acidification during urea transformation was significantly decreased ( P  < 0.01). These findings suggest that to achieve long-term effects of chitosan in soils, applying it as a chitosan-gibbsite complex is a better option.

Reply to Hosseini Monjezi, B.; Lützenkirchen, J. Comment on “Zhou et al. Adsorption Behaviors of Lanthanum (III) and Yttrium (III) Ions on Gibbsite. Minerals 2023, 13, 1530”

Zongke Zhou,Quan Wan,Wenbin Yu,Xin Nie,Shuguang Yang,Shuqin Yang,Zonghua Qin