A critical review of Allura Red removal from water: Advancements in adsorption and photocatalytic degradation technologies, and future perspectives

This review comprehensively surveys the extant methodologies for the removal of Allura Red (AR), a widely used synthetic azo dye, from contaminated water sources; the two major technologies utilized are adsorption and photocatalytic degradation. The novelty of this review paper consists in synthesizing the advances in knowledge about the adsorption and photodegradation of AR and in putting forward practical ways to overcome certain obstacles standing in the way of water treatment technology. This review, therefore, highlights the developments made in the techniques of adsorption and photocatalysis, assesses the various tools and techniques employed and their influences on the removal efficiency, and discusses the potential and prospects for the development of these techniques in improving their performance in water treatment. It further looks into the mechanisms involved with these technologies, evaluating their efficiency, cost-effectiveness, as well as the environmental impact. Moreover, it describes the latest development of new adsorbents and photocatalysts, as well as underlines all promising features of these materials for the improvement of the dye removal process. Focusing on easily scalable and sustainable solutions, current bottlenecks are discussed in this review and new trends and future prospects were investigated that might help to overcome these issues. Overall, the work will be an asset for those carrying out dye removal studies and will form a basis for assessing current technologies and propelling future innovations in this area.