A reusable Fe3O4/GO-COOH nanoadsorbent for Ca2+ and Cu2+ removal from oilfield wastewater

https://doi.org/10.1016/j.cherd.2020.12.019Get rights and content

Highlights

  • The Fe3O4/GO-COOH nanoadsorbent had efficient adsorption ability.

  • The nanoadsorbent had relatively high reusability.

  • The oil recovery significantly increased by using the treated oilfield wastewater.

Abstract

Oilfield wastewater contains a large number of metal ions (such as Ca2+ and Cu2+). Reinjection in oil wells without treatment would affect oil recovery. To remove Ca2+ and Cu2+ ions, we prepared a reusable Fe3O4/GO-COOH nanoadsorbent by the magnetization and carboxylation of graphene oxide (GO). The Ca2+ and Cu2+ removal percents of the nanoadsorbent reached 78.4% and 51% at 60 min, respectively. After five adsorption/desorption cycles, the nanoadsorbent retained high recovery rates (82.1% for Ca2+ and 91.8% for Cu2+) and removal percents (72.3% for Ca2+ and 49.33% for Cu2+). In the simulated indoor oil recovery test, oilfield wastewater treated with Fe3O4/GO-COOH could enhance oil recovery (EOR) by 11.0% compared with untreated oilfield wastewater. The novel magnetic nanoadsorbent could not only adsorb metal ions in oilfield wastewater effectively to enhance oil recovery (EOR) but could also be quickly recycled and reused, which shows promising application prospects in oil exploitation.

Introduction

The oil exploitation industry usually produces plenty of wastewater (Hu et al., 2016; Delazare et al., 2014). An optional way to avoid environmental pollution is reinjection of the wastewater into oil wells as a displacement solution for oil recovery. However, most oilfields only remove oil and suspend in wastewater, and metal ions are rarely removed. Therefore, the salinity of oilfield wastewater is very high (Aljuboury et al., 2019). These oilfields want to enhance oil recovery by using oil displacement agents which can overcome high salinity water (Yang et al., 2020). Because the highly concentrated metal ions in solution, such as Ca2+ and Cu2+, may lead to difficulty in emulsifying water and oil while largely hindering the recovery efficiency. Common separation technologies include chemical sedimentation, resin exchange, membrane separation, physical adsorption, biological treatment and so on (Range and Hawboldt, 2018). Adsorption treatment is always considered one of the most common methods for ion removal from oilfield wastewater at low cost (Ali and Gupta, 2006; Hou et al., 2015; Wang et al., 2016; Shen et al., 2019). Adsorbents are basically divided into humic acids, carbon, minerals, polymers, biomaterials and so on. Most of the adsorbents have the advantages of active functional groups and large specific surface area. But the center of the adsorbent limits the development of most of them due to their high price and the difficulty in handling after adsorption (Nabil and Ibrahim, 2018; Devaraj et al., 2019; Afshari et al., 2020). Among various adsorbents, graphene oxide (GO) has outstanding capability in ion binding due to abundant oxygen-containing functional groups (Huang et al., 2019; Chen et al. 2020). Yang et al. found that the capacity of GO is eight times that of activated carbon in adsorbing Cu2+ (Yang et al., 2010). Other metal ions, such as Ca2+, can also be adsorbed by GO via electrostatic interactions (Terracciano et al., 2017). Since oxygen-containing functional groups are primary contributors to adsorption, promoting GO’s oxidation degree can effectively enhance the adsorptive capacity and reduce the adsorption time for metal ions (Chang et al., 2017). COO groups can further provide stronger electrostatic attractions to ions, especially multivalent metal ions (Zhao et al., 2019). Ma et al. found that the maximal U(IV) adsorption capacity of carboxylated GO is 315 mg/g, notably higher than that of GO (190 mg/g) under the same conditions (Ma et al., 2019). Carboxylation is therefore a very useful and practical method to promote the absorbability of GO. In addition, in an economic sense, good reusability is required for adsorbents used in the oil exploitation industry to deal with huge amounts of wastewater. If adsorbents can be recycled or used for other high valorization strategies (Bădescu et al., 2018), they will further relieve environmental contamination. Magnetization is a simple and effective method to recycle adsorbents. Cai et al. used magnetic activated carbon to effectively treat electroplating wastewater and recycled the adsorbent frequently (Cai et al., 2018). Cai et al. magnetized biological carbon with a good adsorption effect for Cr(VI) and recovered it effectively (Cai et al., 2019).

In this study, the nanoadsorbent Fe3O4/GO-COOH was prepared through magnetization and carboxylation of GO, followed by a series of characterization experiments. Then, Ca2+ and Cu2+ removal percents were tested for the adsorbent, and the reusability was assessed after recycling the adsorption/desorption process five times. Finally, the treated wastewater was utilized as a displacement solution in a simulated crude oil recovery experiment, and the enhancement of recovery efficiency was effectively estimated to suggest the significant performance of the novel adsorbent.

Section snippets

Materials

Sodium dodecylbenzene sulfonate (SDBS, 98%, Greagent), FeCl3·6H2O (99%, Adamas), FeSO4·7H2O (99%, Adamas), NaNO3 (99%, Adamas), H2O2 (30% in H2O, Aladdin), NH3·H2O (28%, J.T. Baker), KMnO4 (99%, Bidepharm), H2SO4 (98%, Bidepharm), C2H5OH (75%, Aladdin), NaCO3 (99.5%, Aladdin) and ClCH2COONa (98%, Aladdin) were used in the experiment. The above reagents were analytically pure (AR).

Preparation of magnetic GO (Fe3O4/GO)

GO was prepared with a modified Hummers method (Chen et al., 2013). The prepared GO (0.2 g) was dispersed in

Characterization and discussion of adsorbent materials

Fig. 2 shows AFM images of GO, Fe3O4/GO and Fe3O4/GO-COOH. Fig. 2 A shows the AFM image of GO, demonstrating that GO has thin layers with a very clear laminated structure. As Fig. 2 B and Fig. 2 C show, there were obvious protruding granules (between GO layers) on the lamellae of GO, which were Fe3O4 magnetic nanoparticles. Fig. 2 C also indicates certain agglomerations of GO layers upon carboxylation. The heights of GO, Fe3O4/GO and Fe3O4/GO-COOH were 1.02, 2.17, and 2.06 nm, respectively.

Discussion

The large amount of oilfield wastewater contained in produced fluid is s difficult to treat properly, so it can only be used for reinjection. However, high salinity of the direct reinjected oilfield wastewater has a negative effect to EOR (Yang et al., 2020).

SDBS is widely used in oilfields because of its low cost and good effect. However, the high content of metal ions in the water injection will cause electrical neutralization, which limits its application. Therefore, oilfields are often

Conclusion

In this study, a kind of magnetic nano-GO-based adsorbent, Fe3O4/GO-COOH, was prepared and characterized by a series of techniques. Relatively high removal percents for Ca2+ and Cu2+ and good reusability have been shown. The simulated oil recovery tests showed that the displacement efficiency of Fe3O4/GO-COOH-treated reinjection water reached 68% after adding SDBS, with an increase of 11% for chemical flooding relative to untreated reinjection water. Unlike most other attempts to use

Conflict of interests

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.

References (43)

  • D. Huang et al.

    Adsorption and desorption of phenanthrene by magnetic graphene nanomaterials from water: roles of pH, heavy metal ions and natural organic matter

    Chem. Eng. J.

    (2019)
  • Y. Huangfu et al.

    Fabrication and investigation on the Fe3O4/thermally annealed graphene aerogel/epoxy electromagnetic interference shielding nanocomposites

    Compos. Sci. Technol.

    (2019)
  • J. Kaur et al.

    Facile fabrication of ternary nanocomposite of MgFe2O4 TiO2@GO for synergistic adsorption and photocatalytic degradation studies

    Ceram. Int.

    (2019)
  • J. Kim et al.

    Effect of pH, sulfate and sodium on the EDTA titration of calcium

    Cement Concrete Res.

    (2003)
  • L. Liu et al.

    One-step vapor-phase assisted hydrothermal synthesis of functionalized carbons: effects of surface groups on their physicochemical properties and adsorption performance for Cr(VI)

    Appl. Surf. Sci.

    (2020)
  • F. Ma et al.

    Preparation of carboxylated graphene oxide for enhanced adsorption of U(VI)

    J. Solid State Chem.

    (2019)
  • Y. Ren et al.

    Adsorption character for removal Cu(II) by magnetic Cu(II) ion imprinted composite adsorbent

    J. Hazard. Mater.

    (2008)
  • C. Shen et al.

    Global profile of heavy metals and semimetals adsorption using drinking water treatment residual

    Chem. Eng. J.

    (2019)
  • R. Singh et al.

    Foam flow in a layered, heterogeneous porous medium: a visualization study

    Fuel

    (2017)
  • A. Terracciano et al.

    Adsorption of Ca2+ on single layer graphene oxide

    J. Environ. Sci. China

    (2017)
  • W. Wang et al.

    Phosphate adsorption performance of a novel filter substrate made from drinking water treatment residuals

    J. Environ. Sci. China

    (2016)
  • Cited by (0)

    1

    These authors contributed equally to this work.

    View full text