Eco-Friendly TiO2 and ZnO Biocar Nanocomposites: Transforming Water Decontamination and Bacteria Inactivation
Authors: Urper Osman , Kharel Prabin , Jothinarayanan Nivedhitha , Krogstad Karoline , Eric-Roseng Lars , Saebo Miina , Aker Walter , Wang Kaiying 
Published: February 2024

Water pollution ranging from harmful chemical substances to pathogenic bacteria is a growing problem from industry to society as a whole[1-2].There is a need to find new, cost-effective sustainable materials with high efficacy to clean up water and to protect the environment. Biocarbon (BC), a material with high specific surface area and large porosity, has some potential for removing water pollutants, but it also has many limitations. However, biocarbon-based composites can be tailored and may have a greater potential for removing contaminants in water. ZnO biochar and TiO2 biochar nanocomposites have been shown to effectively remove harmful chemical substances, such as industrial dyes, and additionally kill potential pathogenic bacteria[2–8].

In this project, we combined TiO2 and ZnO with biochar to create an active nanocomposite surface to see if this could be a cost-effective method to deactivate bacteria and degrade specific dyes. We present the fabrication and examination of TiO2/biochar (BC) and ZnO/BC composite photocatalysts, synthesized via hydrolysis technique. These catalysts were designed for the purpose of methyl orange (MO) degradation and bacterial strain inactivation. A comprehensive assessment of these catalysts was carried out using a number of sophisticated methods, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and UV-Vis spectrophotometry for evaluation of degradation. Moreover, the direct contact method was used for antibacterial analysis. Our findings underline the exceptional properties of these composites for water decontamination and antibacterial efficacy. The nanocomposites showed remarkable photocatalytic performance in MO removal from wastewater, achieving a superior removal efficiency of 92%, as shown in Figure 1. This can be attributed to their outstanding electron transfer efficacy. In addition, the TiO2/BC and ZnO/BC nanocomposites manifested robust antibacterial properties, and they showed an antibacterial effectiveness of 85% against Escherichia coli (E. coli) (Table 1). This research highlights the promising potential of TiO2/BC and ZnO/BC nanocomposites as eco-friendly and multifaceted materials, suggesting a wide range of potential applications in water purification and antibacterial activity.

Acknowledgments: The authors acknowledge the research grants from project # 6000237-13

Figure:

Figure 1. Photocatalytic degradation of MO (initial concentration; 20 mg/L) under solar light irradiation, a) Pure BC and TiO2, and composite TiO2/BC catalysts, b) Pure BC and ZnO, and ZnO/BC catalysts.

Table:

Table 1. Antimicrobial efficiency of 5 different catalysts against E. coli.

References

[1] A. S. Eltaweil, I. M. Mamdouh, E. M. Abd El-Monaem, and G. M. El-Subruiti, “Highly Efficient Removal for Methylene Blue and Cu2+onto UiO-66 Metal-Organic Framework/Carboxylated Graphene Oxide-Incorporated Sodium Alginate Beads,” ACS Omega, 2021, doi: 10.1021/acsomega.1c03479.

[2] J. Hidalgo-Jimenez et al., “Phase transformations, vacancy formation and variations of optical and photocatalytic properties in TiO2-ZnO composites by high-pressure torsion,” Int J Plast, vol. 124, pp. 170–185, Jan. 2020, doi: 10.1016/j.ijplas.2019.08.010.

[3] A. S. Eltaweil, A. M. Abdelfatah, M. Hosny, and M. Fawzy, “Novel Biogenic Synthesis of a Ag@Biochar Nanocomposite as an Antimicrobial Agent and Photocatalyst for Methylene Blue Degradation,” ACS Omega, vol. 7, no. 9, pp. 8046–8059, Mar. 2022, doi: 10.1021/acsomega.1c07209.

[4] S. Riaz and S. J. Park, “An overview of TiO2-based photocatalytic membrane reactors for water and wastewater treatments,” Journal of Industrial and Engineering Chemistry, vol. 84. Korean Society of Industrial Engineering Chemistry, pp. 23–41, Apr. 25, 2020. doi: 10.1016/j.jiec.2019.12.021.

[5] L. Lu, R. Shan, Y. Shi, S. Wang, and H. Yuan, “A novel TiO2/biochar composite catalysts for photocatalytic degradation of methyl orange,” Chemosphere, vol. 222, pp. 391–398, May 2019, doi: 10.1016/j.chemosphere.2019.01.132.

[6] R. Zha, R. Nadimicherla, and X. Guo, “Ultraviolet photocatalytic degradation of methyl orange by nanostructured TiO2/ZnO heterojunctions,” J Mater Chem A Mater, vol. 3, no. 12, pp. 6565–6574, Mar. 2015, doi: 10.1039/c5ta00764j.

[7] J. Liu et al., “Preparation, environmental application and prospect of biochar-supported metal nanoparticles: A review,” Journal of Hazardous Materials, vol. 388. Elsevier B.V., Apr. 15, 2020. doi: 10.1016/j.jhazmat.2020.122026.

[8] J. Liu et al., “Preparation, environmental application and prospect of biochar-supported metal nanoparticles: A review,” Journal of Hazardous Materials, vol. 388. Elsevier B.V., Apr. 15, 2020. doi: 10.1016/j.jhazmat.2020.122026.

Figure 1