New insights on nanostructure of ordered mesoporous Fesingle bondMn bimetal oxides (OMFMs) by a novel inverse micelle method and their superior arsenic sequestration performance: Effect of calcination temperature and role of Fe/Mn oxides

https://doi.org/10.1016/j.scitotenv.2020.143163Get rights and content

Highlights

  • A series of OMFMs were successfully fabricated via a novel inverse micelle method.

  • Calcination temperature affected the nanostructure and surface chemistry of OMFMs.

  • SiO32−/PO43− ions and HA significantly influenced on both As(III) and As(V) removal.

  • Redox transformation of arsenic in liquid-solid phase was simultaneously investigated.

  • Respective role of Fe/Mn oxides in OMFM-3 for arsenic removal was identified.

Abstract

A series of ordered mesoporous Fesingle bondMn bimetal oxides (OMFMs) were fabricated by using a novel inverse micelle method, and the texture, nanostructure and interface chemistry properties of OMFMs were closely correlated to the calcination temperature. Due to the amorphous regular inner-connected nanostructure and bimetallic synergistic effect, the obtained OMFMs exhibited superior arsenic sequestration performance than pure mesoporous Fe oxides (PMF) and Mn oxides (PMM). The optimum ratio of Fe/Mn and calcination temperature for arsenic removal was 3/1 and 350 °C (OMFM-3), and the maximum As(III) and As(V) adsorption capacities of OMFM-3 were 174.59 and 134.58 mg/g, respectively. Solution pH value negligibly affected the uptake of arsenic (ranged from 3.0 to 7.0), while SiO32−/PO43− ions and humic acid (HA) displayed significant inhibitory effect on arsenic removal by OMFM-3. According to the mechanism of arsenic removal, which simultaneously analyzed the arsenic redox transformation in aqueous phase and on solid phase interface, it was concluded that manganese oxides in OMFM-3 mainly played the role as a remarkable As(III) oxidant in water, whereas iron oxides dominantly acted as an excellent arsenic species adsorbent. Finally, the prominent arsenic sequestration behavior and performance in surface water suggested that OMFM-3 could be a promising and hopeful candidate for arsenic-contaminated (especially As(III)) surface water and groundwater remediation and treatment.

Introduction

To address adverse human health effect resulting from the exposure of inorganic arsenic contaminated wastewater and/or drinking water, numerous effective technologies have been developed over the past few decades (Meng et al., 2012; Kumar et al., 2019; Moraga et al., 2019; Wang et al., 2019; Xi et al., 2019; Xiong et al., 2019; Wen et al., 2020a; Zhou et al., 2020). Among these arsenic purification techniques, adsorption is recognized as a promising method and best option available owing to its easy operation, low cost and high removal efficiency (Kim et al., 2020; Ma et al., 2020). Adsorption process between inorganic arsenic and natural minerals, especially iron/iron-based substances, plays an important role in its mobility, speciation and bioavailability in biosphere such as water, sediment and soil environment (Guo et al., 2012; Huang et al., 2019). Thus, some iron/iron-based adsorbents have been extensively used as effective adsorbents to remove inorganic arsenic due to their high selectivity and strong affinity (Li et al., 2015; Sun et al., 2017; Zhang et al., 2017a; Zhang et al., 2017b; Zhang et al., 2018; Sun et al., 2019b). Nevertheless, the primary disadvantage of those pure iron/iron-based (hydr)oxides is low uptake of arsenic, which may be associated with the inherent structural characteristics of adsorbents such as lower specific area and pore volume. Another drawback is that As(III) at natural environmentally-relevant pH adsorbs to various iron-based adsorbents less strongly than As(V) because of the non-ionic form of As(III) (H3AsO3) in water (Chen et al., 2018). Therefore, a pre-oxidation step is often required before conventional adsorption process in order to gain higher As(III) removal efficiency (Wen et al., 2015; Shan et al., 2020). However, any additional chemical oxidizing agents can not only induce the operating complexity and cost, but also generate the harmful by-products and cause the second pollution.

Considering the above-mentioned, a proper oxidant has been directly incorporated into the pure iron (hydr)oxides to fabricate excellent iron-based bimetallic adsorbents. Manganese (Mn) oxides, specifically MnO2, are deemed to be effective oxidants in As(III) oxidation. Although MnO2 could readily oxidize As(III) in water (Manning et al., 2002), however, the total As removal efficiency would sharply decrease with increasing the MnO2 percentage in iron-based bimetal composites due to the fact that pure MnO2 is much lower As(V) capacity than that of pure iron (hydr)oxides (Tresintsi et al., 2013). Thus, the exploitation and utilization of contained-MnO2 adsorbents is limited in As(III)-contaminated water/wastewater treatment. Therefore, facilitating the oxidation of soluble As(III) by manganese oxides and reducing the adverse effect of MnO2 is becoming a necessity to achieve effective total As removal efficiency by Fesingle bondMn bimetal oxides. Previous study had shown that Mn(III/IV) content in Fesingle bondMn binary oxides played an important role in high uptake of arsenic in aqueous owing to the oxidation process of As(III) (Zhang et al., 2014). This result indicated that Mn(III) content in binary oxides seems could effectively avoid the drawbacks and would not damage the oxidation capacity of pure Mn oxides. Consequently, Mn(III) content in Fesingle bondMn bimetal oxides are anticipated to the excellent oxidants for As(III) because Mn(III) intermediates that produced along with the redox reactions between As(III) and MnO2 could also oxidize As(III) into As(V) in water (Manning et al., 2002). In addition, according to the evidence of oxidation capacity, some authors deduced that Mn(III), rather than Mn(IV), played a major role in the oxidation of organic compounds because it possessed a higher redox potential (McBride, 1989; Ukrainczyk and McBride, 1992; Nico and Zasoski, 2001; Remucal and Ginder-Vogel, 2014), and the content of Mn(III) in Mn oxides is a rate controlling factor during the process of contaminants oxidation (Sun et al., 2019a).

Additionally, except for remarkable oxidation property for As(III), this Mn-contained bimetal oxides adsorbent also needs remarkable adsorption performance for the generated As(V) to gain effective total As removal efficiency. Ordered mesoporous metal oxides (MMOs), have been focused on recently owing to their intrinsic larger specific surface area and pore volume, uniform and tunable pore size, as well as extremely well-ordered inner-connected nanostructure (Ren et al., 2012). Such features correspond well with the requirements as remarkable adsorbents (Wu and Zhao, 2011; Teng et al., 2013). Currently, soft template and hard template are two kinds of traditional and popular methods to fabricate the MMOs (Gregory et al., 2017). However, some drawbacks, such as the rapid hydrolysis and polymerization of metal ions precursors, the poor wettability of templates, stem from these two conventional methods extensively confine the practical application of MMOs (Gu and Schüth, 2014). In addition, calcination process in high temperature should be added in order to gain highly crystalline MMOs, because the stability of the adsorbents in water/wastewater treatment must also be carefully considered. Nevertheless, the ordered meso-structures of target products easily collapse when the templates are removed during the heat treatment, especially in soft template methods. Furthermore, calcination in different temperature may also dramatically affect the characteristics and properties of nanomaterials, for instance, crystallinity, crystallite size, specific surface areas, and valence state of nanomaterials, which are dependent on the adsorption performance of MMOs. To pursue this aim, it is imperative to develop a novel method to synthesize the perfect MMOs and clarify the correlation between the calcination temperature and the interface chemistry of MMOs.

In this study, we employ a novel and ingenious inverse micelle method, which can overcome the shortcomings from the soft and hard templates, to fabricate a series of ordered mesoporous Fesingle bondMn bimetal oxides (OMFMs) via the heat treatment. The effect of calcination temperature on nanostructure characteristics and interface chemistry properties of OMFMs are extensively detected. Then, some efforts are made to examine the adsorption behavior and performance of arsenic in water by using the OMFMs. Finally, both As(III) and As(V) removal by OMFMs in liquid-solid two phase are systematically investigated to identify the respective role of Fe/Mn oxides. Aiming to deep understand the correlation between the calcination temperature and adsorption performance of OMFMs, clarify the respective role of iron/manganese oxides and design the superior adsorbents for arsenic elimination and immobilization from water.

Section snippets

Chemicals and nanomaterials

All chemicals involved in this work were analytical-grade and without further purification. Arsenic stock solution (1000 mg/L) were prepared by using inorganic As(III/V) (NaAsO2/Na2HAsO4·7H2O, Sigma-Aldrich). Manganese nitrate (Mn(NO3)2·4H2O), ferric nitrate (Fe(NO3)3·9H2O) and 1-butanol were purchased from Aladdin (Shanghai, China), and P123 (EO20PO70EO20) was obtained from Sigma-Aldrich. The working solution of As(III) and As(V) with desired concentration was prepared by diluting the arsenic

Textural and structural properties of nanomaterials

Fig. 1a–b demonstrates the N2 adsorption/desorption isotherms and BJH pore size distribution of nanomaterials in different calcination temperature. As can be seen, all type IV adsorption/desorption isotherms, the characteristic H1 hysteresis loops as well as narrow monomodal pore size distribution suggested that nanomaterials in this study maintained the ordered mesoporous structure (Mogudi et al., 2017). Besides, increasing the calcination temperature of ordered mesoporous Fesingle bondMn bimetal oxides

Conclusions

A series of OMFMs were fabricated via a novel inverse micelle method in this work, and the correlation between the calcination temperature and the interface chemistry of OMFMs were extensively explored. The results indicated that the textural properties and nanostructure of obtained OMFMs were closely related to the calcination temperature, which further affected the removal efficiency of arsenic. OMFMs (except for OMFM-4) displayed excellent arsenic removal behavior than pure mesoporous Fe/Mn

CRediT authorship contribution statement

Jun Lu: Methodology, data collection and writing-original draft preparation;

Zhipan Wen: Conceptualization, draft writing and editing, revised the manuscript, supervision;

Yalei Zhang and Gang Cheng: Designed some experiments and made deep discussion;

Rui Xu, Xiaohu Gong and Xin Wang: Conducted some characterizations of the samples;

Rong Chen: Designed some experiments and made deep discussion.

All authors discussed the results and commented on the manuscript.

Declaration of competing interest

The authors declared that they have no conflicts of interest to this work.

Acknowledgements

This work was financed by the National Natural Science Foundation of China (No. 51708427). We also sincerely thank the Associate Editor (Prof. Daniel CW Tsang) and two anonymous reviewers, whose constructive comments and valuable suggestions significantly improved the quality of the manuscript.

References (56)

  • Y. Meng et al.

    Preparation of new base-aluminum-chloride-loaded fiber as adsorbent for fast removal of arsenic(V) from water

    Chin. Chem. Lett.

    (2012)
  • R. Miao et al.

    Mesoporous TiO2 modified with carbon quantum dots as a high-performance visible light photocatalyst

    Appl. Catal. B

    (2016)
  • B.M. Mogudi et al.

    Promotion effects of alkali- and alkaline earth metals on catalytic activity of mesoporous Co3O4 for 4-nitrophenol reduction

    Appl. Catal. B

    (2017)
  • B. Moraga et al.

    Copolymer-hydrous zirconium oxide hybrid microspheres for arsenic sorption

    Water Res.

    (2019)
  • Y. Sun et al.

    Zero-valent iron for the abatement of arsenate and selenate from flowback water of hydraulic fracturing

    Chemosphere

    (2017)
  • B. Sun et al.

    Bisulfite triggers fast oxidation of organic pollutants by colloidal MnO2

    J. Hazard. Mater.

    (2019)
  • Y. Sun et al.

    Multifunctional iron-biochar composites for the removal of potentially toxic elements, inherent cations, and hetero-chloride from hydraulic fracturing wastewater

    Environ. Int.

    (2019)
  • C. Wang et al.

    Metal-organic frameworks for aquatic arsenic removal

    Water Res.

    (2019)
  • Z. Wen et al.

    Synthesis of ordered mesoporous iron manganese bimetal oxides for arsenic removal from aqueous solutions

    Microporous Mesoporous Mater.

    (2014)
  • Z. Wen et al.

    Nanocasted synthesis of magnetic mesoporous iron cerium bimetal oxides (MMIC) as an efficient heterogeneous Fenton-like catalyst for oxidation of arsenite

    J. Hazard. Mater.

    (2015)
  • Z. Wen et al.

    Facile template-free fabrication of iron manganese bimetal oxides nanospheres with excellent capability for heavy metals removal

    J. Colloid Interface Sci.

    (2017)
  • Z. Wen et al.

    Redox transformation of arsenic by magnetic thin-film MnO2 nanosheet-coated flowerlike Fe3O4 nanocomposites

    Chem. Eng. J.

    (2017)
  • Z. Wen et al.

    One-step facile hydrothermal synthesis of flowerlike Ce/Fe bimetallic oxides for efficient As(V) and Cr(VI) remediation: performance and mechanism

    Chem. Eng. J.

    (2018)
  • Z. Wen et al.

    Simultaneous oxidation and immobilization of arsenite from water by nanosized magnetic mesoporous iron manganese bimetal oxides (Nanosized-MMIM): synergistic effect and interface catalysis

    Chem. Eng. J.

    (2020)
  • Z. Wen et al.

    Facile inverse micelle fabrication of magnetic ordered mesoporous iron cerium bimetal oxides with excellent performance for arsenic removal from water

    J. Hazard. Mater.

    (2020)
  • Y. Xi et al.

    Performance and mechanism of arsenic removal in waste acid by combination of CuSO4 and zero-valent iron

    Chem. Eng. J.

    (2019)
  • Y. Xiang et al.

    Fabrication of sustainable manganese ferrite modified biochar from vinasse for enhanced adsorption of fluoroquinolone antibiotics: effects and mechanisms

    Sci. Total Environ.

    (2020)
  • X. Xiong et al.

    Potentially toxic elements in solid waste streams: fate and management approaches

    Environ. Pollut.

    (2019)
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