Semiconductor-mediated photocatalysis plays a pivotal role in the elimination of organic pollutants from water systems. Titanium dioxide (TiO2) and zinc sulphide (ZnS) semiconductors are commonly utilized as photocatalysts in water purification due to their physical and chemical stability and also large band gap. The drawbacks of both semiconductors, nevertheless, prevent them from being used in real and large-scale treatments. Therefore, binary and ternary-based TiO2/ZnS nanostructured materials may be a promising solution to improve the quantum efficiency, structural, and electrical features of pure TiO2 and ZnS semiconductors for improved photoefficiency. This review aims to unravel the development of binary TiO2/ZnS and the modification of ternary photocatalysts (TiO2/ZnS-X, X = metal, non-metal, and dye sensitization) by various approaches. The engineered TiO2/ZnS-based ternary nanostructured materials have exhibited exceptional performance to accelerate the degradation of organic pollutants in wastewater. These materials were fabricated by modifying TiO2/ZnS binary composite and embedding co-catalysts like carbonaceous material, polymeric material, transition metal, metal oxide, and metal. The relationship between the properties of the resulting nanomaterials and their photocatalytic performances has been examined. This review has also placed a special focus on the synthetic routes applied to derive the binary and ternary TiO2/ZnS composites. Another aim of this review is to scrutinize the factors that influence the performance of binary and ternary-based TiO2/ZnS composites on the degradation of organic pollutants. Opportunities for further investigation have been also outlined, along with limitations and impediments based on the current findings.
Assessment of activity levels of radionuclides that exist in soil, granite, and charnockite rock samples is very crucial because it exhibits an enhanced elemental concentration of uranium (U) and thorium (Th) contributing higher natural background activity than usual in the environment and it may cause health risk to human health through the external and internal exposure. This study determined the radioactivity levels of 238U, 232Th, and 40K radionuclides in soil, granite, and charnockite rock samples collected from selected fields in Ekiti State, Nigeria using Caesium iodide CsI(Tl) scintillation gamma spectrometer. It also evaluated indices of the radiological parameters consisting of radium equivalent activity (Raeq), absorbed dose rate (DR), annual effective dose equivalent (AEDE), internal hazard index (Hin), and excess lifetime cancer risk (ELCR). The calculated average activity concentrations of 238U, 232Th, and 40K are 30.40 ± 0.71 Bq kg-1, 3.31 ± 0.05 Bq kg-1, and 222.25 ± 14.72 Bq kg-1, respectively, which were lower than their respective world average values. Comparatively, potassium concentrations in these collected samples have a higher value than concentrations of uranium and thorium (40K > 238U > 232Th). All the evaluated values of the radiological parameters (except DR) of the appraised radionuclides were below the global permissible limits. The granite rocks, charnockite rocks, and soils from Ekiti State in Nigeria do not pose any hazardous risk to humans, but continued monitoring is necessary when these materials are used as building materials, which cause long-term radiation exposure.