COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Yanjun Ou,Shuhua Ma,Xiaohui Wang,Hao Wu,Helong Hui,Yi Zhang
China produces over 50 % of global alumina , but its dependence on imported bauxite is as high as 65 %. Local bauxite in China is of low grade. During mining, high-grade ores were sold, while low-grade ores were left piled up on site. This practice not only occupied a large land area but also caused serious pollution. Additionally, kaolinite and diaspore are embedded in a complex and dispersed distribution on the micron scale. The physical separation and ore phase dissociation of these two (kaolinite and diaspore) are very difficult, thereby preventing the economical and efficient utilization of Chinese bauxite using existing mineral flotation and sintering technologies. Based on the analysis of the molecular structure of kaolinite , this study found a significant difference in the dissolution rates of kaolinite and diaspore in a low-alkali solution. This conclusion was drawn through a combination of kinetic analysis and experimental exploration. Therefore, a new chemical pre desilication method of diaspore bauxite rich in kaolinite was proposed. The experiment found that at temperature of 180 ℃ and Na 2 O concentration of 20 g/L, the solubility of kaolinite in a low alkali solution was 3.3 g/L. After 40 minutes of reaction, the maximum dissolution of kaolinite reached 4.2 g/L. Under the same conditions, the solubility of diaspore was 0.064 g/L. The results of kinetic study showed that the activation energy of pure kaolinite dissolution reaction was 26.77 kJ/mol, which belongs to diffusion control. Conversely, the dissolution reaction activation energy of pure diaspore was 84.30 kJ/mol, which belongs to chemical reaction control . In low alkali systems, there was a significant difference in dissolution rate between the two. By optimizing the process conditions, the optimal process conditions were found. Under the optimal conditions, the aluminum silicon ratio increased from 3.22, 2.91, and 2.68–7.92, 8.42, and 8.17, respectively, by processing three types of low-grade bauxite with different particle sizes. It is noteworthy that this method can achieve a significant increase in bauxite A/S only requiring two simple processing steps: alkali dissolution and liquid-solid separation. This study not only fills the research and application gap of low alkali solutions in the field of bauxite beneficiation, but also helps to support the green and sustainable development of the world's alumina industry.
研究领域:
矿物加工工程
·
材料科学与工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2021
·
IF 5.467
Junming Zhou,Hongmei Liu,Dong Liu,Peng Yuan,Hongling Bu,Peixin Du,Wenxiao Fan,Mengyuan Li
Weathered crust elution-deposited rare earth (WED-RE) ores are important rare earth element (REE) resources around the world. In these ores, the REE are believed to mainly exist as exchangeable REE(III) ions on the surfaces of clay minerals, such as tubular halloysite and platy kaolinite . However, the mechanisms underlying the sorption and desorption of REE(III) ions on clay minerals in the environment of weathered crusts remain ambiguous. In this study, the sorption/desorption characteristics of Eu(III) ions onto halloysite and kaolinite were investigated. The results revealed that Eu(III) was adsorbed onto both clay minerals through inner-sphere complexation and outer-sphere complexation, where the former was the primary sorption mechanism. Halloysite displayed a higher sorption capacity for Eu(III) than kaolinite in a weakly acidic environment (pH 4–6). The desorption efficiency increased with the increasing concentration of NH 4 + ions. When the NH 4 + concentration was 0.002 mol/L, which is similar to the typical cation concentration of groundwater/rainwater, the amount and rate of Eu(III) desorption from halloysite were lower than those from kaolinite. The desorption of Eu(III) ions from the two clay minerals is proposed to be governed by the attraction between the outer-sphere complexes and clay minerals when the NH 4 + concentration is 0.002 mol/L. Therefore, halloysite has a higher sorption capacity and stronger retention capacity for Eu(III) than kaolinite, which suggests that halloysite may play a greater role in REE(III) enrichment in WED-RE ores than kaolinite owing to the similar chemical properties of REE(III) ions. The fundamental results obtained in this study afford new insights into the migration of REE and the role of clay minerals in REE enrichment during ore formation.
研究领域:
地质学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2022
·
IF 6.76
Xiaolei Zhang,Ziying Wang,Yangsai Lyu,Jia Li,Kun Song,Ningning Xing,Dickon H.L. Ng
Near-infrared (NIR) light-powered nanomotors with active motion have attracted extensive attention in the chemo-photothermal therapy of cancer. However, there are also some limitations such as complicated synthesis process, low permeability of drugs and viscous physiological environment. Herein, we developed a facile route to synthesize novel NIR light-powered DOX/Au-m-HTAS nanomotor based on natural halloysite (HNTs) for active chemo-photothermal therapy. Such nanomotor exhibited NIR light controlled on/off motion with a maximum speed of 64.5 μm/s. Owing to the synergetic NIR light-powered motion and chemo-photothermal therapy, DOX/Au-m-HTAS nanomotor could effectively adhere tumor cells, leading to deeper cell penetration, higher cellular uptake, and better ablation of tumor cells. Meanwhile, DOX/Au-m-HTAS nanomotors also had enhanced ability for CT imaging of local tumor, demonstrating the enhanced anticancer efficiency. This strategy provided a new insight into the chemo-photothermal synergistic therapy of tumors.
研究领域:
纳米技术
·
癌症治疗
·
生物医学工程
·
材料科学
·
成像技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Sustainable Metallurgy
·
2025
·
IF 3.2
Shao Shuang,Ma Baozhong,Wang Chengyan,Chen Yongqiang
Extracting Al from coal gangue has the double benefits of realizing the high-value application of coal gangue and mitigating the scarcity of bauxite resource. The key Al-containing minerals in coal gangue include kaolinite and boehmite, and thermal activation is pivotal for stimulating their reactivity. In this study, kaolinite and boehmite were subjected to thermal activation and acid leaching to explore the intrinsic link between their thermal evolution and leaching activity. Results showed that the phase evolution of kaolinite followed a multi-step sequential process in the order of kaolinite → metakaolinite → γ -Al 2 O 3 → mullite, and Al V in metakaolinite was highly active. For boehmite, it underwent the transformation of boehmite → γ -Al 2 O 3 → δ -Al 2 O 3 → θ -Al 2 O 3 and α -Al 2 O 3 successively. Their reactivity in descending order was γ -Al 2 O 3 > δ -Al 2 O 3 > boehmite > α -Al 2 O 3 . Furthermore, a comparative study of leaching temperature demonstrated that elevated temperature favorably strengthened the thermodynamic driving force and greatly promoted the Al extraction. This study is of some theoretical significance for guiding the thermal activation and acid leaching of coal gangue. Graphical
研究领域:
矿物加工
·
材料科学
·
冶金学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2022
·
IF 5.907
Qiubei Gu,Jing Liu,Yixuan Yang,Runliang Zhu,Lingya Ma,Xiaoliang Liang,Shiqin Long,Jianxi Zhu,Hongping He
Ion-adsorption rare earth deposits (IAREDs) are important source for rare earth elements (REEs). The transportation, accumulation, fractionation, and leaching of REEs in IAREDs are mainly controlled by the interactions between REEs and mineral geosorbents. The coexisting ions can significantly affect the mineral-REEs interactions, which, however, are not currently well studied. This work investigated the effects of sulfate (SO 4 2− ) on the adsorption of REEs on kaolinite and ferrihydrite, two typical mineral geosorbents in IAREDs with distinct surface properties. The obtained results indicate that, with increasing SO 4 2− concentration, the adsorption of REEs is hardly changed on kaolinite but remarkably enhanced on ferrihydrite. Additionally, SO 4 2− can particularly improve the adsorption of middle REEs on ferrihydrite. The in situ ATR-FTIR spectra results, coupled with 2D correlation spectroscopic analysis, indicate that the promoted adsorption of REEs by SO 4 2− on Fh is attributed to both the electrostatic attraction and the formation of Fe-REE-SO 4 ternary complexes. However, the negatively charged kaolinite can hardly adsorb SO 4 2− because of the strong electrostatic repulsion between them. Desorption experiments reveal that REEs can be more efficiently desorbed by NH 4 Cl from kaolinite than from ferrihydrite. The obtained results suggest that coexisting oxyanions have profound effects on the mineral-REEs interactions, which should be taken into consideration while exploring the transportation, accumulation, and fractionation of REEs in IARED.
研究领域:
矿物学
·
环境科学
✓ 已验证
DOI
高影响因子
Materials
·
2019
·Vol. 12
·期 22
·3780
·
IF 2.972
Xianfeng Yue,Rong Zhang,Huairui Li,Minglei Su,Xiaobei Jin,Daochun Qin
Benzyl ammonium chloride (BAC) is a broad-spectrum bactericide, but vulnerable to leaching by water. In this paper, halloysite nanotubes (HNT) and montmorillonite (MMT) were used as drug carriers to load BAC, in order to achieve good anti-mildew activity and long-term sustained release properties. The HNT and MMT nano-composites were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and nitrogen adsorption/desorption. XRD results showed that BAC intercalated the interlayer of MMT, and expanded the interlayer spacing from 1.15 nm to 1.75 nm. Pore analysis showed that BAC decreased the cavity of halloysite nanotubes to a certain extent, which indicated that BAC loaded inside the lumen of HNT successfully. TG analysis showed that the loading capacity of MMT to BAC was higher than HNT. The accelerated-release experiments revealed both two clays have significant sustained-release effects on BAC, and the releasing rate of HNT was relatively lower. Both HNT and MMT have promising application prospects as sustained-release carriers. The inhibition test showed that BAC in nano-clay has good anti-mildew resistance performance.Keywords:Benzyl ammonium chloride;halloysite nanotubes;montmorillonite;sustained release;anti-mildew
研究领域:
材料科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
·
2020
·
IF 4.872
Haojing Zhang,Taotao Lu,Ruoyu Zhang,Mengjie Wang,Srinivasan Krishnan,Shanhu Liu,Yanmei Zhou,Deliang Li,Zhichong Qi
Antibiotics, a highly prevalent class of environmental organic pollutants, are becoming a matter of global concern. Clay minerals that are ubiquitous in subsurface environments may play an important role in the fate and transport of antibiotics. Taking ciprofloxacin (CIP) as a model antibiotic, this work explored the role of clay colloids (kaolinite and montmorillonite) on the adsorption and transport of CIP under different chemical solution conditions. The adsorption isotherms showed that montmorillonite colloids had a larger CIP sorption capacity than kaolinite colloids. The results of transport experiments indicated that montmorillonite colloids could promote CIP transport in saturated sand columns, but the addition of kaolinite colloids affected CIP mobility to a much smaller extent. The much stronger transport-enhancement effect of montmorillonite colloids was due to CIP adsorbed strongly to the colloids and desorption hysteresis of colloid-adsorbed CIP, likely stemming from the intercalation of this antibiotic in the interlayer of montmorillonite. Interestingly, transport of clay colloids increased with the increasing pH from 5.0 to 9.0; however, CIP transport decreased with the increasing pH in the presence of clay colloids. The observations were likely attributable to pH-dependent ciprofloxacin adsorption/desorption to clay minerals. Increasing the concentrations of NaCl and CaCl 2 generally decreased the contaminant-mobilizing ability of montmorillonite colloids, mainly by increasing the aggregation of colloids and thus, decreasing the transport of colloid-adsorbed CIP. Moreover, under the test conditions (1 mM NaCl and pH 7.0), the presence of CIP inhibited the transport of clay colloids due to the increase in aggregate size of clay colloids with the addition of CIP. Overall, these findings suggest that clay colloids with high adsorption abilities for antibiotics in the subsurface environment may act as a carrier for certain antibiotic compounds.
研究领域:
环境科学
·
污染生态学
✓ 已验证
DOI
PubMed
高影响因子
APPLIED CLAY SCIENCE
·
2016
·
IF 2.586
Zongrong Wang,Wan Zheng,Zhenqian Zhang,Likun Chen,Zhongfei Zhang,Yong Li,Ning Ma,Piyi Du
A kaolinite-serine intercalation compound was synthesized via the guest displacement method. Serine molecules were intercalated into kaolinite to form kaolinite-serine through exchange between serine and the guest molecules ethylene glycol or water, which was inserted into the interlayer space of kaolinite beforehand. The thickness of kaolinite-serine particles decreased to 14 nm from 30 nm of raw kaolinite after intercalation. The interlayer distance of kaolinite reached approximately 1.13 nm after the intercalation of serine molecules. The serine molecules inserted in the interlayer space of kaolinite molecules were arranged in a flattened monolayer configuration and partially compressed into the tetragonal holes in the silicate layer. The activation energy Ea for releasing the pre-intercalated molecule before ultimate exchanging with serine determines the intercalation degree of serine into kaolinite. Higher Ea makes the expansion of kaolinite with pre-intercalated molecules more stable, which will facilitate the final intercalation of serine. The activation energy is 6.95 kJ/mol for ethylene glycol and 21.2 kJ/mol for water, respectively, resulting in serine intercalation degree of 45%, and 85% correspondingly. The kaolinite-serine intercalation compound is expected to be applied in the pharmaceutical and cosmetics fields.
研究领域:
材料科学
·
化学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2024
·
IF 8.2
Yinhua Zhong,Yue Cheng,Huiying Zhang,Ran Wei,Jinzhi Ni,Weifeng Chen,Hui Jia
Biomass burning (e.g., wildfire) frequently occurs globally, inevitably produces abundant biomass-burning smoke-derived dissolved organic matters (BBS-DOMs) which eventually deposits on the surface environment. The adsorption and fractionation of BBS-DOMs on clays inevitably alter their biogeochemical process and environmental behaviors in the surface environment. It is therefore important to clarify the adsorption and fractionation of BBS-DOM on clay surfaces. This study found that the fractionation of BBS-DOMs on clays (montmorillonite and kaolinite) were controlled by their functional groups, aromaticity, molecular size and organic components. The spectral indexes (SUVA 254 and S 275 – 295 ) of BBS-DOMs in solution after clays adsorption suggested that with the increasing DOC concentration, the primary interaction between BBS-DOMs and clays changed from hydrogen bond to hydrophobic/pore filling effects, and the adsorption ratio of the large molecules increased, which were very different from natural fulvic acid . Furthermore, various BBS-DOMs and fulvic acid had different component fractionation behaviors during clay adsorption, because they had different abundances of protein-like matters (hydrogen bond donors), pyridine-N/pyrimidine-N (positive charge doners of electrostatic interaction), and fulvic-like matters (hydrophobic interaction and pore filling effect). Additionally, the increasing pH weakened the adsorption of bulk BBS-DOMs and enhanced the adsorption ratio of aromatic matters and smaller BBS-DOM molecules. Meanwhile, at a higher pH, the adsorption ratio of protein-like matters increased, while the adsorption ratio of humic- and fulvic-like matters decreased. The result was ascribed to the enhanced hydrogen bond between protein-like matters and clays as well as the enhanced electrostatic repulsion between humic−/fulvic-like matters and clays. This study is helpful for deeply understanding the multimedia-crossing environmental behavior of BBS-DOMs in the surface environment.
研究领域:
环境科学
·
土壤学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yafei Zhao,Shu Guo,Xin Xue,Chengli Xiong,Xiangyang Gao,Bing Zhang
Rational design of efficient, low-cost and eco-friendly catalysts for hydrogen generation from solid-state hydrogen storage material ammonia borane (AB) is identified as an ideal approach for solving the problems of energy crisis and environmental pollution. Herein, we construct a robust and low-cost composite catalyst with the combination of non-noble metal cobalt phosphide (Co 2 P), carbon dots (CDs) and halloysite nanotubes (HNTs), in which CDs serve as the bridge and conductive mediator to link Co 2 P and HNTs for facilitating electron transfer. Attributing to the synergistic effects among Co 2 P, CDs and HNTs, the high conductivity of CDs and the dispersion/supporting of HNTs, the as-prepared Co 2 P-CDs/ m HNTs composite catalyst displays a considerably high hydrogen evolution rate with TOF of 178.02 mol H2 mol co2P −1 min −1 , which is much higher than Co 2 P/HNTs, Co 2 P/CDs and other non-noble metals-based catalysts. This work provides a new insight and bridging strategy for the design of low-cost composite catalysts with excellent performance toward AB hydrolysis.
研究领域:
材料科学
·
能源化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
NANO
·
2019
·
IF 1.293
Mengmeng Zhang,Yamin Cheng,Zhiwei Li,Xiaohong Li,Laigui Yu,Zhijun Zhang
An inorganic–organic nanohybrid flame retardant, HNT@CS@Fe 3 O 4 , is prepared by Halloysite nanotubes (HNT) as nanotemplate, chitosan (CS) as char-forming agent and ferroferric oxide (Fe 3 O 4 ) playing in a catalytic role, aiming to endow enhanced flame-retardant performance of its nanohybrid. Results show that HNT@CS@Fe 3 O 4 nanohybrids have a corn-like structure and can significantly improve the flame retardancy and thermal stability of epoxy resin (EP). Especially, the initial thermal degradation temperature of EP/HNT@CS@Fe 3 O 4 is significantly improved by 2 4 ∘ C relative to pure EP, and the residual carbon yield under air atmosphere is 8.8 wt.%, which is significantly higher than other EP composites, indicating a higher thermal stability is offered by the as-prepared nanohybrid. The limiting oxygen index of EP/10HNT@CS@Fe 3 O 4 is 31.3%, which is 10.2% higher than that of pure EP. Meanwhile, the HNT@CS@Fe 3 O 4 nanofiller reduces the peak heat release rate, CO production and peak smoke production release of EP nanocomposite by 32.0%, 44.0% and 33.0% in a cone calorimeter test, respectively. This is because the HNT-based composite can form a three-dimensional network structure into the EP matrix to inhibit heat release and diffusion of flammable moieties upon burning of EP. In the meantime, the incorporated Fe 3 O 4 nanoparticle can in situ catalyze the charring of CS and EP matrix on the surface of HNT during the combustion process, which also contributes to the significantly increased fire safety of EP.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2021
·
IF 5.467
Min Xia,Haibo Liu,Hanlin Wang,Fuwei Sun,Xuehua Zou,Tianhu Chen,Ziyang Chu,Dong Chen,Yuefei Zhou,Qiaoqin Xie
Clay minerals and iron oxide usually coexist in soil. This work revealed the effect of the interaction between halloysite (HNTs) and hematite on the environmental fate of organic pollutants. Methylene blue (MB) was used as a probe molecule to investigate the effect of this interaction on the adsorption and degradation of MB in the presence of H 2 O 2 . The experimental results showed that the presence of hematite changed the Zeta potential of HNTs and weakened the adsorption capacity of HNTs to MB, but the existence of HNTs improved the dispersion of hematite and hence enhanced the performance for activating H 2 O 2 to degrade MB. The adsorption and degradation of other organic pollutants (e.g. 2,4-dichlorophenol, phenol, sulfadiazine, sodium) were similar to MB. The hydroxyl radicals (·OH) were the dominant reactive species confirmed by quantitative experiments, radical scavenging studies and ESR spectra. In addition, with the participation of hematite, the adsorbed methylene blue on the halloysite surface was also removed via activating H 2 O 2 . Consequently, these findings are of significance to understand the migration, enrichment, degradation of organic pollutions.
研究领域:
环境科学
·
土壤学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）