Repurposing Industrial and Agricultural Wastes as Sustainable Alternatives in Photovoltaic Cells and Dye Degradation

Abstract Combustion of coal at thermal power plants generates enormous amounts of coal fly ash (CFA). Proper disposal of CFA is an important issue today because environmental problems are considered a burning issue worldwide. On the other hand, groundnut shells (GNS), regarded as agricultural waste in general, litter landfills everywhere and create soil degradation. Since both CFA and GNS contain abundant silica, this work focuses on extracting amorphous silica from these materials through a total dissolution–precipitation process. The silica was extracted from it and used to prepare titanium oxide (TiO₂) hybrids. The GNSS were extracted from GNS, and the CFAS was extracted from the CFA. The methods used were based on sol–gel. These hybrids were further tested for the performance of their solar cells in dissolving dyes. The overall results of the obtained physical properties of CFAS and GNSS are similar to those of conventional silica. More importantly, TiO₂/GNSS and TiO₂/CFAS hybrids showed enhanced photocatalytic efficiency compared to the pure TiO₂. Therefore, it is evidence of repurposing CFA and GNS, which have high potential for use as sustainable applications in renewable energy and environmental remediation.