Introduction of vacancy capture mechanism into defective alumina microspheres for enhanced adsorption of organic dyes
Graphical abstract
Introduction
Water contaminated by organic dyes is becoming a potential threat to human health and environment, because a majority of them are carcinogenic, teratogenic and genotoxic [1], [2], [3], [4]. Therefore, there is an urgent need to develop effective methods to remove organic dyes from water. Adsorption is one of the most effective technologies that have been widely adopted to achieve this purpose [5], [6], [7], [8], [9]. However, the practical application of traditional absorbents such as activated carbon is often limited by their low adsorption capacity [10], [11], [12], [13], [14]. Hence, it is high demand for developing high-efficiency adsorbents to remove organic dyes.
Alumina-based materials with hierarchical structure have attracted considerable attention owing to its low cost and environmentally benign nature [15], [16], [17]. Compared with traditional bulk adsorbents, the hierarchical structured alumina-based materials exhibited enhanced removal performance in water pollutants. For instance, Al2O3@ZnO core–shell microfibers [18], γ-Al2O3 hollow microspheres [19] and nanoparticles [20] showed improved adsorption performance for congo red. For spindle like γ-Al2O3 [21], it has been used to remove congo red (176.7 mg/g), phenol (21.0 mg/g), and Cd(II) (10.1 mg/g) in water. However, the adsorption capacities of these alumina-based materials are still not satisfactory, and it is imperative to design efficient alumina-based adsorbents to remove organic dyes.
Recently, creating defects (e.g., oxygen vacancies) in material has proved to be a promising approach to improve its performance owing to great number of surface active sites and high surface energy [22], [23], [24], [25], [26], [27]. More specifically, introducing oxygen vacancies into catalysts not only change coordination structure, but also regulate the surfaces electronic state, which in turn influence the intrinsic reactivity [28]. For instance, increasing the abundance of oxygen vacancies to photocatalysts, such as TiO2−x [29], ZnO1−x [30], can greatly improve their activity by narrowing bandgap and extending visible light absorption. In some case, the presence of oxygen vacancies can obviously reduce the resistance of charge-transfer and lower the adsorption energy of H2O molecules, and thus improving the electrocatalytic activity [31], [32]. In addition, oxygen vacancies formed played a critical role in promoting photoinduced charge separation, leading to an increased photocatalytic activity towards the reduction of CO2 [33]. Similarly, the key roles of oxygen vacancies in promoting the adsorption and activation of reactant molecules have been fully demonstrated [34], [35], [36]. Upon contact, oxygen vacancies can change the state of the reactants (eg, bond length, bond angle, coordination pattern, or intermediates), thereby increasing the affinity for the reactants. Zhang et al. [25] reported the high adsorption affinities of oxygen vacancy-rich WOx/C nanowires for Pb2+ and methylene blue. Although the relationship between defects and catalytic performance has been widely investigated in heterogeneous catalysis. The specific role of defects in adsorption performance of alumina-based materials for organic dyes have not been identified and clarified to date. Therefore, it is very meaningful to adjust the adsorption performance of materials with defects.
Our previous research found that the microsphere-shaped materials generally have larger specific surface area, well-developed pore structure and abundant functional groups [37], [38], [39], [40]. This allows such materials to expose more active sites, thus showing better adsorption performance. Therefore, in this work, we designed alumina into a spherical shape and use it to remove organic dyes. The aims of this work are to develop high-efficiency adsorbents for dye removal, and then give detailed analysis about the role of the defects in dye removal, finally discuss adsorption mechanism for dye on the defective alumina microspheres (DF-AlOx).
Section snippets
Synthesis of materials
The chemical reagents used were purchased from Sinopharm Chemical Regent Beijing Co., Ltd., including aluminum nitrate (Al(NO3)3·9H2O), acetic acid (HAc), isopropanol (IPA), congo red (CR, C32H22N6Na2O6S2), methyl blue (MB, C37H27N3Na2O9S3) and methyl orange (MO, C14H14N3SO3Na). The chemical structure of CR and MB are displayed in Fig. S1.
The preparation process for the DF-AlOx is as follows. Firstly, 30 mmol Al(NO3)3·9H2O was placed in a mixed solution (60 mL) containing HAc and IPA, and then
Characterization of materials
The as-obtained DF-AlOx was successfully synthesized via a solvothermal reaction by using Al(NO3)3·9H2O as metal salt, HAc and IPA acetic acid as solvent, as demonstrated in Fig. 1a. Firstly, the Al(NO3)3·9H2O, HAc and IPA were hydrothermally treated at 200 °C for 2 h to form the precursor of the DF-AlOx (step I). Subsequently, the resulting precursor was calcinated under N2 atmosphere to obtain the final product (step II). The as-obtained DF-AlOx was characterized using XRD and SEM to verify
Conclusions
In this work, defective alumina microspheres were prepared and used as adsorbent to remove organic dyes from aqueous solution. The DF-AlOx microspheres have amorphous structure and present yellow colour, which are different from the ordinary alumina. The DF-AlOx microspheres possess coordinatively unsaturated Al-species, large surface area, abundant oxygen-containing groups and oxygen vacancies. Due to its structural characteristics, the DF-AlOx microspheres exhibit excellent adsorption
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was supported by National Natural Science Foundation of China (51808037), Fundamental Research Funds for the Central Universities (FRF-TP-19-020A2) and Natural Science Foundation of Guangdong Province (2020A1515011197).
References (81)
- et al.
Ultrahigh adsorption capacities for anionic and cationic dyes from wastewater using only chitosan
J. Clean. Prod.
(2019) - et al.
3D-Printed metal-organic frameworks within biocompatible polymers as excellent adsorbents for organic dyes removal
J. Hazard. Mater.
(2020) - et al.
Competitive removal of Pb2+ and malachite green from water by magnetic phosphate nanocomposites
Water Res.
(2019) - et al.
Adsorption dynamics of methyl violet onto granulated mesoporous carbon: facile synthesis and adsorption kinetics
Water Res.
(2016) - et al.
Superb adsorption capacity of hierarchical calcined Ni/Mg/Al layered double hydroxides for Congo red and Cr(VI) ions
J. Hazard. Mater.
(2017) - et al.
Characterization and utilization of industrial microbial waste as novel adsorbent to remove single and mixed dyes from water
J. Clean. Prod.
(2019) - et al.
Removal of volatile odorous organic compounds over NiAl mixed oxides at low temperature
J. Hazard. Mater.
(2018) - et al.
MgAl-LDH/Biochar composites for methylene blue removal by adsorption
Appl. Clay. Sci.
(2019) - et al.
Hierarchical porous Al2O3@ZnO core-shell microfibres with excellent adsorption affinity for Congo red molecule
Appl. Surf. Sci.
(2019) - et al.
Facile synthesis of hierarchical porous gamma-Al2O3 hollow microspheres for water treatment
J. Colloid Interface Sci.
(2014)
Solvent-free hydrothermal synthesis of gamma-aluminum oxide nanoparticles with selective adsorption of Congo red
J. Colloid Interface Sci.
Construction of crystal defect sites in N-coordinated UiO-66 via mechanochemical in-situ N-doping strategy for highly selective adsorption of cationic dyes
Chem. Eng. J.
MOF-derived CoN/N-C@SiO2 yolk-shell nanoreactor with dual active sites for highly efficient catalytic advanced oxidation processes
Chem. Eng. J.
Construction of dual defect mediated Z-scheme photocatalysts for enhanced photocatalytic hydrogen evolution
Appl. Catal. B: Environ.
Defect-rich ZnO nanosheets of high surface area as an efficient visible-light photocatalyst
Appl. Catal. B: Environ.
One-step fabrication and characterization of hierarchical MgFe2O4 microspheres and their application for lead removal
Microporous Mesoporous Mater.
Insights into adsorption mechanism for fluoride on cactus-like amorphous alumina oxide microspheres
Chem. Eng. J.
Facile synthesis of iron-based oxide from natural ilmenite with morphology controlled adsorption performance for Congo red
Appl. Surf. Sci.
Performance and mechanism of Mg/Fe layered double hydroxides for fluoride and arsenate removal from aqueous solution
Chem. Eng. J.
Removal of cobalt(II) ion from aqueous solution by chitosan-montmorillonite
J. Environ. Sci.
Morphology controlled synthesis of hierarchical structured Fe2O3 from natural ilmenite and its high performance for dyes adsorption
Appl. Surf. Sci.
Novel Al-doped carbon nanotubes with adsorption and coagulation promotion for organic pollutant removal
J. Environ. Sci.
3D hierarchical graphene oxide-NiFe LDH composite with enhanced adsorption affinity to Congo red, methyl orange and Cr(VI) ions
J. Hazard. Mater.
Untapped conversion of plastic waste char into carbon-metal LDOs for the adsorption of Congo red
J. Colloid Interface Sci.
Hierarchical flower-like nickel(II) oxide microspheres with high adsorption capacity of Congo red in water
J. Colloid Interface Sci.
TiO2 hollow microspheres with mesoporous surface: superior adsorption performance for dye removal
Appl. Surf. Sci.
Nickel nanoparticles encapsulated in porous carbon and carbon nanotube hybrids from bimetallic metal-organic-frameworks for highly efficient adsorption of dyes
J. Colloid Interface Sci.
A green biochar/iron oxide composite for methylene blue removal
J. Hazard. Mater.
Morphology-dependent properties and adsorption performance of CeO2 for fluoride removal
Chem. Eng. J.
Selective removal of anionic dyes with exceptionally high adsorption capacity and removal of dichromate (Cr2O72-) anion using Ni-Co-S/CTAB nanocomposites and its adsorption mechanism
J. Hazard. Mater.
Strong adsorption of phosphate by amorphous zirconium oxide nanoparticles
Water Res.
An efficient removal of methyl orange dye from aqueous solution by adsorption onto chitosan/MgO composite: a novel reusable adsorbent
Appl. Surf. Sci.
One-pot synthesis of sandwich-like MgO@Carbon with enhanced sorption capacity of organic dye
Chem. Eng. J.
A hierarchically porous MgFe2O4/γ-Fe2O3 magnetic microspheres for efficient removals of dye and pharmaceutical from water
Chem. Eng. J.
One-pot synthesis of highly efficient MgO for the removal of Congo red in aqueous solution
J. Mater. Chem. A
EDTA-cross-linked beta-cyclodextrin: an environmentally friendly bifunctional adsorbent for simultaneous adsorption of metals and cationic dyes
Environ. Sci. Technol.
Porous PVDF/GO nanofibrous membranes for selective separation and recycling of charged organic dyes from water
Environ. Sci. Technol.
Influence of dissolved organic matter on the removal of 12 organic micropollutants from wastewater effluent by powdered activated carbon adsorption
Water Res.
Thermal decomposition and recovery properties of ZnAl-CO3 layered double hydroxide for anionic dye adsorption: insight into the aggregative nucleation and growth mechanism of the LDH memory effect
J. Mater. Chem. A
Comparative study on the removal of different-type organic pollutants on hierarchical tetragonal bismutite microspheres: adsorption, degradation and mechanism
J. Clean. Prod.
Cited by (99)
Promising adsorbent for dye detoxification: Exploring the potential of chitosan sodium carboxymethylcellulose silk fibroin aerogel
2024, International Journal of Biological MacromoleculesAlumina microspheres for the adsorption of fatty alcohols containing oxygenates in Fischer-Tropsch synthetic oils
2023, Separation and Purification TechnologyNovel 3D sphere-like β-In<inf>2</inf>S<inf>3</inf>/Biochar nanoflowers for remediation of dyes in single and binary systems and interpretation using statistical physical modeling
2023, Environmental Nanotechnology, Monitoring and ManagementA novel mesoporous carbon nanospheres-based adsorbent material with desirable performances for dyes removal
2023, Journal of Molecular LiquidsPolyoxometalates as highly efficient adsorbents for ciprofloxacin removal: The key role of oxygen vacancies
2023, Journal of Molecular Structure