Synthesis of antibacterial sorbent based on waste photographic fixing solution

Clean water is of great importance for human life and health; however, water does not always meet the necessary microbiological standards and needs to be purified before it is delivered to the end consumer. One of the dangerous indicators is the presence of Escherichia coli bacteria in water, which can cause dangerous illnesses and death, thereby causing harm to both individuals and the economy. To purify water from this type of bacteria, the use of silver-containing adsorbents is promising.

Our institute has long been working on the sorption of antibacterial adsorbents, the action of which is enhanced by silver. This metal has been used for centuries as an antimicrobial agent, and in recent years, interest in its antibacterial properties has increased due to the emergence of antibiotic resistance.
In medicine, radiography is used to diagnose certain diseases. In the process of producing a photograph, waste remains: a spent photographic fixing solution, which contains on average up to 1% silver. It was decided to develop a method for modifying montmorillonite-containing clay with silver from these solutions. In this way, two problems are solved at once: a method is generated for the useful disposal of waste solutions and a method is created for the synthesis of an antibacterial adsorbent.
An ammonia solution of silver was prepared by adding ammonia to the spent fixing solution. Then, a glucose solution, which contains an aldehyde group, was added to this solution and montmorillonite-containing clay was added as an initiator of sediment aggregation. When heated, the silver was reduced and precipitated.
Further research indicated a silver content of 0.5% in the sediment. Theoretically, this is enough for the manifestation of antibacterial properties. Practical tests of the effect of the sorbent on the growth and development of Escherichia coli in vitro are currently being carried out.