Photocatalytic remediation of crude oil contaminated water from nigeria by visible light active BiOI/TiO 2 heterojunction photocatalyst Blessing Ogoh-Orch, Patricia Keating, Aruna Ivaturi University of Strathclyde, UK Titanium dioxide (TiO 2 ) is widely used for photocatalytic mineralization of crude oil and other organic pollutants in water due to its outstanding properties such as non-toxicity, chemical and biological inertness, photo stability, resistance to chemical, low cost and photo corrosion [1]. However, can only absorb in the UV region due to its wide band gap (anatase, 3.2 eV), thereby limiting its applications with only 5-8% of UV light from the solar spectrum being utilised [2]. To overcome this problem, bismuth oxy-iodide (BiOI)/titanium dioxide (TiO 2 ) heterojunction photocatalysts were synthesised with different levels of BiOI deposited via sequential ionic layer adsorption and reaction (SILAR) method on doctor bladed TiO 2 mesoporous layers coated on FTO substrates for comparative analysis of photocatalytic degradation of methyl orange (MO), 4-chlorophenol (4-CP) and crude oil in water under visible light irradiation. The formation of BiOI/TiO 2 was confirmed by XRD, STEM, SEM-EDX, and the band structure of the composite was determined by UV-Vis diffused reflectance (DRS) measurement. Result of the DRS showed an improved absorption of the synthesized BiOI/TiO 2 in the visible light region with optical band gap of 3.21 eV, 2.16 eV, 2.02 eV, 2.00 eV and 1.98 eV for TiO 2, 2xBiOI/TiO 2 , 4xBiOI/TiO 2 , 6xBiOI/TiO 2 and 8xBiOI/ TiO 2 respectively [where the integer represents the number of SILAR cycles, e.g. 4xBiOI/TiO 2 is sample with 4 BiOI SILAR cycles]. Preliminary evaluation of the photocatalytic performance of the synthesized photocatalysts for MO degradation confirmed that four SILAR cycles (4xBiOI/TiO 2 ) is the optimal with its reaction rate constant 13 times higher than that of TiO 2 . Its efficiency was further proven by degrading 4-CP (3 h) and crude oil (48 h) achieving 38.3 % and 88.64 % degradation efficiency respectively, compared with the degradation efficiency of 0.0 % (4-CP) and 84.26 % (crude oil) achieved with TiO 2 . The degradation of crude oil even using the unmodified TiO 2 indicates the important role of adsorption along with photolysis in remediation of crude oil contaminated water. References
1. Y. Li, Q. Zhang, J. Jiang andL. Li, Environmental Technology , 1-11, (2019). 2. M.M. Mahlambi, C.J. Ngila and B.B. Mamba, A Review. J. Nanomater ., 1-30, (2015).
P79
© The Author(s), 2022
Made with FlippingBook Learn more on our blog