Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
632236 | Journal of Membrane Science | 2016 | 13 Pages |
Abstract
Polyethyleneimine (PEI) is an inexpensive low-toxic polymer and is used for the preparation of thin film composite (TFC) nanofiltration (NF) membranes. One serious problem with most of the reported high salt rejecting (ca. 90% divalent cation) PEI-based TFC membranes is the low permeate flux and low average monovalent to divalent anion selectivity. There is also no comparative study of antifouling property of the PEI TFC membranes with conventional poly(piperazineamide) TFC membrane. Herein, we report an approach for the in situ manipulation of permeation behavior and antifouling property of PEI-based TFC NF membrane. The approach was based on the use of dextran (Dex) conjugate of PEI (PEI-Dex) as a new monomer or co-monomer for the interfacial polymerization (IP) with trimesoyl chloride (TMC). Particularly, membranes prepared with mixture of PEI-Dex (2.5%, w/v)+PEI (0.25%, w/v) showed ca. 86Â Lmâ2Â hâ1Â MPaâ1 pure water permeate flux and 84%, 85% and 37% rejections of Na2SO4, MgCl2 and NaCl, respectively. On the other hand, membrane prepared with PEI (0.25%, w/v) alone gave much lower permeate flux (37Â Lmâ2Â hâ1Â MPaâ1). The membrane prepared with PEI-Dex (3%, w/v) gave permeate flux as high as 163Â Lmâ2Â hâ1Â MPaâ1 with ca. 71%, 72% and 10% rejections of Na2SO4, MgCl2 and NaCl respectively under similar experimental conditions. All the PEI-based membranes prepared under suitable experimental conditions showed high average monovalent to divalent ions (cation and anion) selectivity. The active layer thickness decreased with increasing proportion of added PEI-Dex into the aqueous bath. This is the reason for the enhancement of permeate flux of the PEI-Dex membranes. On the other hand, low membrane surface charge at neutral feed pH is responsible for the higher average monovalent to divalent ions selectivity. The PEI-based membranes exhibited much improved antifouling/antiscaling properties compared to that of conventional poly(piperazineamide) TFC NF membranes. These types of membranes are suitable for long-term water softening without frequent cleaning step.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Filtration and Separation
Authors
Anupam Bera, Jaladhi S. Trivedi, Suresh K. Jewrajka, Pushpito K. Ghosh,