Cellulosic metallic nanocomposites for photocatalytic degradation of persistent dye pollutants in aquatic bodies: A pragmatic review

Zero water insecurity (comfortable accessibility to healthy water for daily basic needs) is a key sustainable development goal underpinned by the United Nations. However, the upsurge in the water pollution pandemic caused especially by effluents discharged from the booming dye industry alongside the emerging of new pollutants has continuously skeletonized water security and poses socio-ecological, and socio-economical threats to humanity. Interestingly, researchers and the (waste) water treatment industries have synergistically become more resilient in taking the bull by the horns to come up with innovative methods like photocatalytic degradation and functional materials like cellulosic metallic nanoparticles (CNCPs) to save the world from this water pollution pandemic and ensure a sustainable and healthy future for our planet. Notably, while photocatalytic degradation allows for complete mineralization of dye in a lesser time compared to other methods, CNCPs allow for excellent degradation and reusability due to their synergistic exceptional properties like biocompatibility, accelerated charge separation and electron transfer, low cost, stability, and eco-beingness. Thus, this work reviewed and summarized several works published on the use of CNCPs for the photocatalytic degradation of hazardous color compounds as well as empirically evaluating the performance of these CNCPs. Several reported methods of CNCPs preparation were documented. Also covered was the re-generability of CNCPs to have a grounded knowledge of CNCPs stability and scalability. It was found that the efficiency of most CNCPs was > 80% for most dyes degraded with the least time taken of <2 min. Also, the CNCPs were revealed to have excellent stability as they can be reused up to 7 cycles with degradation capacity remaining >70 %. In the end, future perspectives and recommendations on dilemmas identified such as circular economic analysis of reused spent CNCPs were made. This will help upcoming researchers and industries that are interested in wastewater treatment to propel this field of study to an upward trajectory of advancement.