Synthesis of eco-friendly ZnO-based heterophotocatalysts with enhanced properties under visible light in the degradation of organic pollutants

Abstract Heterogeneous photocatalysts have been widely used for the removal of various organic pollutants from wastewater. The main challenge so far resides in the sustainability of the process, with regard to the synthesis and the application under visible light. In this study the precipitated materials from the Moringa oleifera seed (MO), groundnut shells (GS) and apatite (A) agrowastes were functionalized with zinc oxide (ZnO) and silver (Ag) solution, to produce a novel bioheterophotocatalysts. Various analytical techniques such as scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and X-ray diffraction (XRD) were used for the characterization of the novel photocatalysts. It was proven that agrowastes can also enhance the photocatalytic activity of a ZnO-based photocatalyst as pure metals. The combination of MO/GS/A/ZnO/Ag in a 1:1:1 ratio resulted in a lower band gap of 1.59 eV, as compared to the band gap of 2.96 eV for ZnO/Ag. These photocatalysts' efficiency was also tested on the photodegradation of polycyclic aromatic hydrocarbon (PAHs) derived from coal leaching in various water sources such as acidic mine drainage, alkaline mine drainage and sewage wastewater. From MO/GS/A/ZnO/Ag, the removal efficiency was found to be 69.59%, 61.07% and 61.68%, compared to 52.62%, 37.96 and 44.30% using ZnO/Ag in acidic mine drainage, alkaline mine drainage and sewage wastewater for 60 min under solar irradiation

Photodegradation of Polycyclic Aromatic Hydrocarbons from Coal Tar into Mine Wastewaters and Sewage Wastewater on a Flat-Bed Photoreactor

Wastewater treatment has been widely focused on the undesirable pollutants derived from various activities such as coking, coal gasification, oil spills, and petroleum. These activities tend to release organic pollutants, however polycyclic aromatic hydrocarbons (PAHs) happen to be highlighted as the most carcinogenic pollutant that easily comes into contact with the environment and humans. It causes major challenges due to its lingering in the environment and chemical properties. Although various techniques such as ions exchange, advanced oxidation, and reverse osmosis have been conducted, some of them have been ignored due to their cost-effectiveness and ability to produce a by-product. Therefore, there is a need to develop and implement an effective technique that will alleviate the organic pollutants (PAHs) in various water sources. In this study, a self-made flat-bed photoreactor was introduced to degrade PAHs in various water sources such as acidic mine drainage, alkaline mine drainage, and sewage wastewater. A previous study was conducted, and only 7.074 mg/L, 0.3152 mg/L and 1.069 mg/L in 4 weeks and thereafter 19.255 mg/L, 1.615 mg/L and 1.813 mg/L in 8 weeks in acidic mine drainage, alkaline mined, drainage, and sewage wastewater leachate from a 2916.47 mg/L of PAHs in coal tar, was analysed. It was found that the flat-bed photoreactor was highly effective and able to obtain a removal efficiency of 64%, 55%, and 58%, respectively; without the flat-bed photoreactor, happened the removal efficiency was of 53%, 33%, and 39%, respectively, in 60 min in acidic mine drainage, alkaline mine drainage, and sewage wastewater. The photodegradation of PAHs was favoured in the acidic mine drainage, followed by sewage wastewater and alkaline mine drainage respective, showing time and solar irradiation dependence

Photodegradation of Polycyclic Aromatic Hydrocarbons from Coal Tar into Mine Wastewaters and Sewage Wastewater on a Flat-Bed Photoreactor

Wastewater treatment has been widely focused on the undesirable pollutants derived from various activities such as coking, coal gasification, oil spills, and petroleum. These activities tend to release organic pollutants, however polycyclic aromatic hydrocarbons (PAHs) happen to be highlighted as the most carcinogenic pollutant that easily comes into contact with the environment and humans. It causes major challenges due to its lingering in the environment and chemical properties. Although various techniques such as ions exchange, advanced oxidation, and reverse osmosis have been conducted, some of them have been ignored due to their cost-effectiveness and ability to produce a by-product. Therefore, there is a need to develop and implement an effective technique that will alleviate the organic pollutants (PAHs) in various water sources. In this study, a self-made flat-bed photoreactor was introduced to degrade PAHs in various water sources such as acidic mine drainage, alkaline mine drainage, and sewage wastewater. A previous study was conducted, and only 7.074 mg/L, 0.3152 mg/L and 1.069 mg/L in 4 weeks and thereafter 19.255 mg/L, 1.615 mg/L and 1.813 mg/L in 8 weeks in acidic mine drainage, alkaline mined, drainage, and sewage wastewater leachate from a 2916.47 mg/L of PAHs in coal tar, was analysed. It was found that the flat-bed photoreactor was highly effective and able to obtain a removal efficiency of 64%, 55%, and 58%, respectively; without the flat-bed photoreactor, happened the removal efficiency was of 53%, 33%, and 39%, respectively, in 60 min in acidic mine drainage, alkaline mine drainage, and sewage wastewater. The photodegradation of PAHs was favoured in the acidic mine drainage, followed by sewage wastewater and alkaline mine drainage respective, showing time and solar irradiation dependence