Applications of photocatalysts in hydrometallurgy: recent achievements and emerging trends

Nowadays, it′s impossible to imagine the metallurgical industry without hydrometallurgical processes. This is due to the need to process ores with lower metal content and stricter environmental standards. Therefore, the search for new technological approaches to metal extraction has become increasingly important. The trend in the development of hydrometallurgical processes is changing. Previously, the primary focus was on finding new sorbents, extractants, flotation reagents, ionic liquids, <i>etc.</i>, to improve extraction efficiency. However, as technological saturation reached, the most effective and stable reagents were identified, and the research shifted toward combining the best materials with methods of physical impact. At that time, significant attention was paid to photocatalytic reactions that could be applied to hydrometallurgical technologies. This opened a new era in separating metals from solid and liquid sources of natural and artificial origin. Photocatalytic approaches were also widely used to address environmental challenges related to the degradation of additional reagents used in hydrometallurgical processes. These reagents include flotation reagents, extractants, and leaching solution components such as cyanide and thiosulfate ions, and are highly toxic pollutants of soil, air, and groundwater. In this review, we examine the use of photocatalytic reactions in hydrometallurgy and discuss key trends in the development of this industry from 2015 to 2026. The review covers different metals that can be most efficiently recovered using photocatalytic reactions. In addition, the challenges are considered related to degradation of additional hydrometallurgical reagents. The use of the photocatalytic approach enables to degrade flotation reagents such as xanthate, octadecylamine, and morpholine; extractants such as tributyl phosphate; and components of leaching solutions such as cyanide and thiosulfate ions. This review helps to assess which of the stateof-the-art hydrometallurgical technologies can be changed or significantly improved using a photocatalytic approach. <br> The bibliography includes 179 references.