An Innovative Photocatalytic Process for Silver Recovery

The photographic industry consumes about 70 million troy ounces of silver annually. The technology used to recover the silver from concentrated solution is more than 40 years old. However, investigators project that, based on industry experience, as much as 20% of this silver is lost in the wash water and goes unrecovered. The toxicity of silver in the effluent is a growing concern in the United States and Europe. An innovative photocatalytic reactor using porous TiO2 as a catalyst for metal recovery is proposed. The unique porous structure allows UV-light to penetrate and treat the waste. The proposed system will be cost-effective because currently unrecovered silver will be recovered, heated wash water will be recycled, and TiO2 will be reused. The proposed work includes fabrication of the porous-TiO2 catalyst and a performance demonstration using the catalyst in a pilot reactor for silver recovery and water reuse. This feasibility study will be completed in 6 months. The proposed photocatalytic reactor has a great potential to become an inexpensive and efficient way to remove and recover silver and reuse wash water in photoprocessing.