A versatile polydimethylsiloxane (PDMS) composite sponge for the removal of organic contaminants from waters

As the global population grows, the introduction of pollutants into aquatic environments increases, posing significant health risks to humans and wildlife. Effective removal of harmful organic contaminants near discharge points can minimize the need for large-scale wastewater treatment technologies. Here, we developed a polydimethylsiloxane (PDMS) sponge with controlled pore size to enhance surface area and sorptive capacity, and further functionalized it to improve adsorption, catalytic capabilities and biocidal properties. The PDMS sponge was tested to remove a wide range of organic contaminants with diverse functionalities covering a Log K_ow range of 0.16 to 6.26. The PDMS sponge showed greater affinity for compounds with larger Log K_ow, likely due to the hydrophobic and lipophilic nature of PDMS itself. This adsorption behavior was found to be linear with respect to Log K_ow, with an R² = 0.8273. Functionalizing the PDMS sponge with activated charcoal significantly improved adsorption efficiency, both in the amount of compounds removed within 24 h and the time required to reduce the initial concentration by half. A photocatalytic experiment with TiO₂-PDMS sponge demonstrated enhanced degradation and removal of organic compounds under UV light. Furthermore, incorporating metallic copper into the PDMS sponge provided antimicrobial properties, reducing E. coli levels by an average of 42% after 4 h of contact. This is promising for bacterial deactivation at the generation point of runoff wastewater streams. These findings provide proof of concept that PDMS sponge composites can be used for remediation and cleanup of urban waters at their entry points.