Detergent Chemistry Impacts the Removal of Silver from Laundry Wastewater

The anti-odor potential of silver nanoparticles has resulted in the use of these particles in clothing. However, parts of these particles get dislodged from the clothes during laundry. The laundry wastewater might eventually reach the environment, which may pose a threat to aquatic organisms.

For this reason, scientists have tried to recover these silver nanoparticles. Recently, a research team has reported in the journal ACS Sustainable Chemistry & Engineering that detergent chemistry has a vital role in determining the amount of silver that can be eliminated from laundry wastewater.

Certain clothing manufacturers include silver nanoparticles into their clothes as they have the ability to kill odor-causing bacteria. However, scientists have discovered that a part of these nanoparticles get washed away during laundry. These silver nanoparticles can be hazardous to various aquatic life forms and might affect the efficacy of bacterial processing in wastewater treatment units. However, recovery of the nanoparticles from laundry wastewater is a complicated process due to lower concentrations of silver nanoparticles in the water, higher concentrations of other ions, and unpredictability over the precise forms of silver nanoparticles present. Sukalyan Sengupta and Tabish Nawaz’s earlier study demonstrated that ion-exchange technology is largely selective for silver. However, their study did not investigate the part played by detergent chemistry, which might hinder this technique. Therefore, the researchers aspired to investigate this in the current study.

The team tested the interaction of silver with individual detergent ingredients. They discovered that silver chiefly occurs as a positively charged ion. This form will react with various detergent compounds under specific conditions. For instance, the positively charged silver ion interacts with negatively charged ions contained in the detergent at distinct pH values. The team also used an ion-exchange resin, which could retrieve nearly 99% of the silver nanoparticles based on the concentration and pH of competing ions. Then, they investigated the resin with detergent components and reused it for more than five cycles. The resin retained the potential to eliminate the silver nanoparticles. However, the incorporation of products such as water-softening agents and bleaching had a negative effect on the efficacy of the resin.

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