Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Jun 22;6(26):16783-16794.
doi: 10.1021/acsomega.1c01296. eCollection 2021 Jul 6.

Bismuth Molybdate Nanoplates Supported on Reduced Graphene Oxide: An Effective Nanocomposite for the Removal of Naphthalene via Adsorption-Photodegradation

Shelter Maswanganyi  1 , Rashi Gusain  2   3 , Neeraj Kumar  2 , Elvis Fosso-Kankeu  1 , Frans Boudewijn Waanders  1 , Suprakas Sinha Ray  2   3
Affiliations

Bismuth Molybdate Nanoplates Supported on Reduced Graphene Oxide: An Effective Nanocomposite for the Removal of Naphthalene via Adsorption-Photodegradation

Shelter Maswanganyi et al. ACS Omega. .

Abstract

Polycyclic aromatic hydrocarbons are a class of persistent organic water pollutants that raise serious concerns owing to their carcinogenicity and other negative impacts on humans and ecosystems. In this study, Bi2MoO6/reduced graphene oxide (rGO) nanocomposites were designed and prepared for the adsorption-assisted photodegradation of naphthalene molecules in an aqueous medium. The synthesized Bi2MoO6 nanoplates and Bi2MoO6/rGO nanocomposites were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, high-resolution transmission microscopy, X-ray photoelectron spectroscopy, ultraviolet spectroscopy, Brunauer-Emmett-Teller, and photoluminescence measurements. The photodegradation of naphthalene molecules was observed to assess the photocatalytic characteristics of the samples under visible light. The Bi2MoO6/rGO nanocomposites exhibited significantly improved photocatalytic efficiency compared to pure Bi2MoO6. Among the nanocomposites, those containing 2 wt % rGO showed the best photocatalytic activity. The incorporation of rGO enhanced the visible light absorption and decreased the recombination rate of photogenerated charge carriers. Moreover, a Bi2MoO6/rGO nanocomposite showed excellent reusability for five cycles.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
XRD patterns of (a) Bi2MoO6, (b) Bi2MoO6/rGO (2 wt % rGO), (c) Bi2MoO6/rGO (5 wt % rGO), and (d) Bi2MoO6/rGO (10 wt % rGO).
Figure 2
Figure 2
FTIR spectra of Bi2MoO6 nanoplates, GO, and Bi2MoO6/rGO (2, 5, and 10 wt % rGO) nanocomposites.
Figure 3
Figure 3
FESEM images of (a) Bi2MoO6 nanoplates and (b) Bi2MoO6/rGO (2 wt %) nanocomposite (b,c) at different magnifications.
Figure 4
Figure 4
HRTEM images of (a) GO, (b,d) Bi2MoO6 nanoplates, (c) d-spacing calculation using the average of 10 fringes in a particular area in (d), and (e–g) Bi2MoO6/rGO (2 wt % rGO) nanocomposite.
Figure 5
Figure 5
(a) STEM image and EDX mapping images, which show homogeneous distributions of C, Bi, Mo, and O, and (b) EDX spectrum of the Bi2MoO6/rGO (2 wt % rGO) nanocomposite.
Figure 6
Figure 6
(a) XPS survey spectra of Bi2MoO6 and the Bi2MoO6/rGO (2 wt % rGO) nanocomposite. High-resolution XPS binding energy spectra: (b) C 1s, (c) O 1s, (d) Bi 4f, and (e) Mo 3d.
Figure 7
Figure 7
(a) UV–vis absorbance spectra, (b) Tauc plots for band gap calculation, (c) N2 adsorption–desorption isotherms, and (d) pore size distribution of Bi2MoO6 and Bi2MoO6/rGO (0, 2, 5, and 10 wt % rGO) nanocomposites.
Figure 8
Figure 8
(a) Effect of contact time on naphthalene adsorption using Bi2MoO6/rGO (2 wt % rGO). (b) Effect of the rGO content of Bi2MoO6/rGO nanocomposites on the removal of naphthalene from wastewater. Conditions: 30 mg of adsorbent (Bi2MoO6/rGO), 100 mL of 50 ppm naphthalene solution, 25 °C, and 60 min.
Figure 9
Figure 9
(a) Effect of the initial naphthalene concentration on the removal efficiency of the Bi2MoO6/rGO (2 wt % rGO) nanocomposite, (b) pseudo-first-order and (c) pseudo-second-order adsorption kinetics, and (d) intraparticle diffusion kinetics of naphthalene adsorption using the Bi2MoO6/rGO (2 wt % rGO) nanocomposite. Conditions: 30 mg of adsorbent [Bi2MoO6/rGO (2 wt %) nanocomposite], 100 mL of naphthalene solutions of 25, 50, 75, and 100 ppm, 25 °C, and 60 min.
Figure 10
Figure 10
Plots of (a) Langmuir and (b) Freundlich adsorption isotherms for the adsorption of naphthalene from wastewater using the Bi2MoO6/rGO (2 wt % rGO) nanocomposite. Red line shows a linear fitting. Conditions: 30 mg of adsorbent [Bi2MoO6/rGO (2 wt % rGO) nanocomposite], 100 mL of naphthalene solution, 25 °C, and 60 min.
Figure 11
Figure 11
(a) Effect of contact time on the photodegradation of 50 ppm naphthalene under 250 W UV–vis light irradiation using Bi2MoO6/rGO nanocomposites. (b) Absorbance intensity of naphthalene at different times during light irradiation for photocatalytic degradation using Bi2MoO6/rGO. (c) LH kinetics model of the photocatalytic degradation of naphthalene in solution. (d) Recyclability of the Bi2MoO6/rGO (2 wt % rGO) nanocomposite for naphthalene photocatalytic degradation up to five cycles.
Figure 12
Figure 12
PL spectra of the Bi2MoO6 nanostructure and Bi2MoO6/rGO (2 wt % rGO) nanocomposite (excitation wavelength = 350 nm).
Figure 13
Figure 13
Plausible mechanism for the removal of naphthalene via adsorption–photodegradation.
See this image and copyright information in PMC

References

    1. Kabra K.; Chaudhary R.; Sawhney R. L. Treatment of hazardous organic and inorganic compounds through aqueous-phase photocatalysis: A review. Ind. Eng. Chem. Res. 2004, 43, 7683–7696. 10.1021/ie0498551. - DOI
    1. Quesada H. B.; Baptista A. T. A.; Cusioli L. F.; Seibert D.; de Oliveira Bezerra C.; Bergamasco R. Surface water pollution by pharmaceuticals and an alternative of removal by low-cost adsorbents: A review. Chemosphere 2019, 222, 766–780. 10.1016/j.chemosphere.2019.02.009. - DOI - PubMed
    1. Gusain R.; Kumar N.; Ray S. S. Recent advances in carbon nanomaterial-based adsorbents for water purification. Coord. Chem. Rev. 2020, 405, 213111.10.1016/j.ccr.2019.213111. - DOI
    1. Ray S. S.; Gusain R.; Kumar N.. Carbon Nanomaterial-Based Adsorbents for Water Purification: Fundamentals and Applications; Elsevier, 2020.
    1. Ama O. M.; Kumar N.; Adams F. V.; Ray S. S. Efficient and cost-effective photoelectrochemical degradation of dyes in wastewater over an exfoliated graphite-MoO 3 nanocomposite electrode. Electrocatalysis 2018, 9, 623–631. 10.1007/s12678-018-0471-5. - DOI