An Innovative Photocatalytic Process for Silver Recovery

EPA Contract Number: 68D70020
Title: An Innovative Photocatalytic Process for Silver Recovery
Investigators: Wang, Chi S.
Small Business: Wangtec Inc.
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: September 1, 1997 through March 1, 1998
Project Amount: $69,465
RFA: Small Business Innovation Research (SBIR) - Phase I (1997) RFA Text |  Recipients Lists
Research Category: Water and Watersheds , SBIR - Water and Wastewater , Small Business Innovation Research (SBIR)


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.

Supplemental Keywords:

small business, SBIR, pollution prevention, wastewater treatment, recycling, engineering, chemistry., RFA, Scientific Discipline, Toxics, Waste, Water, Sustainable Industry/Business, National Recommended Water Quality, Chemical Engineering, cleaner production/pollution prevention, Wastewater, Environmental Chemistry, Sustainable Environment, Chemistry, Technology for Sustainable Environment, Hazardous Waste, Chemistry and Materials Science, Engineering, Hazardous, Engineering, Chemistry, & Physics, Environmental Engineering, wastewater treatment, Silver, photocatalytic reactor, recovery, silver recovery, catalysts, recycling, TiO2, recovery of heavy metals, metal removal

Progress and Final Reports:

  • Final