Aim of the work was the preparation of novel membranes to be applied in the field of wastewater treatment. Membranes were prepared by modifying the surface of an ultrafiltration commercial PES membrane in order to get a hydrophilic nanostructured coating. Prepared membranes were characterized by Scanning Electron Microscopy (SEM) in order to investigate membrane morphology, contact angle measurements in order to study their superficial properties, water permeability and fouling tests. Furthermore, textile model dyes wastewater was used in order to evaluate membrane rejection towards two different model dyes: Remazol Brilliant Blu and Acid Red. Modified membranes showed a more dense structure in comparison to PES commercial ones made up of a network of interconnected channels constituting the porous region and the membrane matrix. From contact angle measurements, modified membranes showed a higher degree of hydrophilicity (45°) in comparison to PES commercial unmodified membranes (68°) with a reduction of about 30% in contact angle values. Water permeability was higher for commercial PES membranes (more than 300 L/m2 h bar) while it was about three times lower (about 100 L/ m2 h bar) for modified novel membranes. Nevertheless, main advantage of modified membranes lied in their property of having a very low tendency to fouling in comparison to PES membranes. This behavior was proved by applying a model foulant compound as humic acid (HA) for filtration tests. After 24h of filtration, with a subsequently backflushing, PES commercial membranes showed a clear tendency to be affected by fouling (it was observed by the deposition of a dark layer on membrane surface). On the contrary, modified novel membranes were less prone to fouling phenomenon especially towards the irreversible type. This aspect was probably due to the smoother surface and to the higher degree of hydrophilicity of modified membranes (as proved by SEM analyses and contact angle measurements) that limited the organic matter to be deposited on membrane surface. Furthermore, regarding dye rejection tests, novel modified membranes showed a Remazol Brilliant Blue and Acid Red removal efficiency higher (more than 10%) than the commercial ones. Our final aim is to produce a very thin nanostructured hydrophilic coating to be used in water purification and in particular in the removal of dyes encountered, for example, in real textile wastewater by applying the novel developed modified membranes in the Membrane Bioreactors (MBRs) technology. Acknowldgement The work is funded by Bionexgen (grant agreement n. CP-FP-246039-2) EU-FP7/project
PES ultrafiltration modified membranes for wastewater treatment
F Galiano;A Figoli;
2013
Abstract
Aim of the work was the preparation of novel membranes to be applied in the field of wastewater treatment. Membranes were prepared by modifying the surface of an ultrafiltration commercial PES membrane in order to get a hydrophilic nanostructured coating. Prepared membranes were characterized by Scanning Electron Microscopy (SEM) in order to investigate membrane morphology, contact angle measurements in order to study their superficial properties, water permeability and fouling tests. Furthermore, textile model dyes wastewater was used in order to evaluate membrane rejection towards two different model dyes: Remazol Brilliant Blu and Acid Red. Modified membranes showed a more dense structure in comparison to PES commercial ones made up of a network of interconnected channels constituting the porous region and the membrane matrix. From contact angle measurements, modified membranes showed a higher degree of hydrophilicity (45°) in comparison to PES commercial unmodified membranes (68°) with a reduction of about 30% in contact angle values. Water permeability was higher for commercial PES membranes (more than 300 L/m2 h bar) while it was about three times lower (about 100 L/ m2 h bar) for modified novel membranes. Nevertheless, main advantage of modified membranes lied in their property of having a very low tendency to fouling in comparison to PES membranes. This behavior was proved by applying a model foulant compound as humic acid (HA) for filtration tests. After 24h of filtration, with a subsequently backflushing, PES commercial membranes showed a clear tendency to be affected by fouling (it was observed by the deposition of a dark layer on membrane surface). On the contrary, modified novel membranes were less prone to fouling phenomenon especially towards the irreversible type. This aspect was probably due to the smoother surface and to the higher degree of hydrophilicity of modified membranes (as proved by SEM analyses and contact angle measurements) that limited the organic matter to be deposited on membrane surface. Furthermore, regarding dye rejection tests, novel modified membranes showed a Remazol Brilliant Blue and Acid Red removal efficiency higher (more than 10%) than the commercial ones. Our final aim is to produce a very thin nanostructured hydrophilic coating to be used in water purification and in particular in the removal of dyes encountered, for example, in real textile wastewater by applying the novel developed modified membranes in the Membrane Bioreactors (MBRs) technology. Acknowldgement The work is funded by Bionexgen (grant agreement n. CP-FP-246039-2) EU-FP7/projectI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
