Functionalized Polycarbonate Commercial Filters for Water Purification

Can commerercially available filtration membranes be easily functionalized in such a way to enhence the removal the charged contaminants in the water treatment process? The literature demonstrates there have been two pioneering works that demonstrated that Ultrathin Self-Assembled Nanoparticle (USANP) membranes (composed of ~5 nm diameter metallic gold nanoparticles surrounded by organic ligands) when applied to commercial membranes displayed charge sensitive rejection to molecular dyes and also have the ability to charge modify the openings in commercial filters. The rejection mechanisms in these works are proposed to be either size dependent or charged based. Recent experimental results have demonstrated that the supporting filter for these USANP membranes can be functionalized solely with highly charged molecular dye Direct Red 80 using no USANP membranes. After functionalization with direct red 80 alone, average rejection for tested molecular dyes at a concentration of 145 µM increased from 31.8 % to 85.6 % even without the addition of a USANP layer. This indicates that dyes themselves are capable of functionalizing the commercial membranes providing an additional method to enhanced rejection of charged contaminants. This poster highlights the efforts made by a Preservice and Early Career Research for Teachers (PERT) team and an Undergraduate student who was awarded an Summer Undergraduate Research Experience Award to measure the rejection results of these two different functionalization methods. Knowledge gained from these experiments may allow for enhanced rejection of charged based contaminants in polluted waters

Azo-Dye-Functionalized Polycarbonate Membranes for Textile Dye and Nitrate Ion Removal

Challenges exist in the wastewater treatment of dyes produced by the world’s growing textiles industry. Common problems facing traditional wastewater treatments include low retention values and breaking the chemical bonds of some dye molecules, which in some cases can release byproducts that can be more harmful than the original dye. This research illustrates that track-etched polycarbonate filtration membranes with 100-nanometer diameter holes can be functionalized with azo dye direct red 80 at 1000 µM, creating a filter that can then be used to remove the entire negatively charged azo dye molecule for a 50 µM solution of the same dye, with a rejection value of 96.4 ± 1.4%, at a stable flow rate of 114 ± 5 µL/min post-functionalization. Post-functionalization, Na+ and NO3− ions had on average 17.9%, 26.0%, and 31.1% rejection for 750, 500, and 250 µM sodium nitrate solutions, respectively, at an average flow rate of 177 ± 5 µL/min. Post-functionalization, similar 50 µM azo dyes had increases in rejection from 26.3% to 53.2%. Rejection measurements were made using ultraviolet visible-light spectroscopy for dyes, and concentration meters using ion selective electrodes for Na+ and NO3− ions

Azo dye functionalized polycarbonate membranes for textile dye and nitrate ion removal - Data and Supplementary Material

The dataset for the article Azo dye functionalized polycarbonate membranes for textile dye and nitrate ion removal is posted here along with videos that show the top and side views of the experiment.https://mds.marshall.edu/physics_data/1000/thumbnail.jp