Ultrahigh Flux and Strong Affinity Poly(N-vinylformamide)-Grafted Polypropylene Membranes for Continuous Removal of Organic Micropollutants from Water

Abstract

The rapid and effective removal of organic micropollutants (OMPs) from water remains a huge challenge for traditional water treatment techniques. Compared with powder adsorbents such as polymers and nanomaterials, the free-standing adsorptive membrane is possible for large-scale applications and shows promise in removing OMPs. Herein, inspired by aquatic plants, a novel free-standing adsorptive membrane (NPPM) with high water flux, strong adsorption affinity, and excellent reproducibility was prepared by one-step UV surface grafting. N-Vinylformamide (NVF) was employed to introduce multiple hydrophilic and hydrogen bonding sites on the surface of commercial polypropylene fiber membranes (PPM). The NPPM exhibits excellent water permeability and ultrahigh water flux (up to 40 000 L/(m 2 h)) and could continuously remove a broad spectrum of OMPs from water. Its adsorption performance is 5−100 times higher than that of PPM and commercial membranes. Even in natural water sources such as tap water and river water, the NPPM shows unchanged adsorption performance and high OMPs removal efficiency (>95%). Notably, the NPPM has excellent regeneration performance and can be regenerated by hot water elution, which provides an environmentally friendly regeneration method without involving any organic solvent. Moreover, the synergy between hydrogen bonding and hydrophobic interaction is revealed, and the hydrophobic interaction provided by the hydrophobic substrate is proved to play a fundamental role in OMPs adsorption. The strong hydrogen bonds between the grafts and the OMPs are demonstrated by variable-temperature FTIR spectroscopy (vt-FTIR), 13 C nuclear magnetic resonance spectroscopy ( 13 C NMR), and simulation calculations. The strong hydrogen bonds could increase the enthalpy change and enhance the adsorption affinity, so the NPPM has a strong adsorption affinity, which is 100 times that of similar adsorption membranes. This study not only presents an adsorptive membrane with great commercial potential in the rapid remediation of a water source but also opens a pathway to develop an adsorptive membrane with high water flux and strong adsorption affinity.

Co‐Aggregation Induced by Amphiphilic Membrane Interface for the Capture of Trace Endocrine Disruptors from Water

“…Clearly, the amphiphilic PNVP grafts on the membrane surface significantly contribute to the capture of BPA molecules from the aqueous phase. In our previous study, [ 44 ] we observed that membranes with a low PNVP grafting ratio (21.7%) achieved a similar adsorption effect to that of a membrane with a high poly(N‐vinyl formamide) (PNVF) grafting ratio (33.8%) under the same conditions (Figure S8b,c, Supporting Information). This observation may be attributed to the fact that the five‐membered ring side groups of PNVP are more hydrophobic than the side groups of PNVF.…”

“…Specifically, there were three hydrophobic methylene moieties and one carbonyl group on each side group of the PNVP grafts, which could contribute to the hydrophobic interactions and hydrogen bonds, respectively. Our previous study [ 44 ] has demonstrated that the hydrophobic interactions provided by the hydrophobic membrane matrix are an important driving force for adsorption. Herein, we propose a mechanism for the adsorption of EDCs on the PVPM.…”

Development of Hydrophilic Polylactic Acid Hollow-Fiber Membranes for Water Remediation

“…On the one hand, hydrogen bonding strengthens the uniformity of the additives and prompts the hydrophilic functional group to play a maximum role. On the other hand, the hydrogen bond itself has a certain renewable nature such that after the pollutants destroy the hydrogen bond structure it recovers when the pollutants are removed . Interestingly, the PLA membranes shows stability in the pH range from 1 to 12 (30 days), but could be degraded by treating in the basic solution with a pH higher than 14.…”

“…On the other hand, the hydrogen bond itself has a certain renewable nature such that after the pollutants destroy the hydrogen bond structure it recovers when the pollutants are removed. 64 Interestingly, the PLA membranes shows stability in the pH range from 1 to 12 (30 days), but could be degraded by treating in the basic solution with a pH higher than 14. Besides, we also find that the PLA hollow-fiber membranes could be degraded by Protease K under certain conditions in 1 week.…”

Efficient selective methylene blue adsorption by polyurethane/montmorillonite‐based antifouling electrospun composite membranes

“…At 665 nm, the adsorbed amount of MB was calculated using a UV–VIS spectrophotometer. The adsorbed amount of MB ( q t ; mg/g) on the PU/MMT membrane was calculated using Equation () 45 where C 0 and C t denote the initial and concentration at time t , respectively (mg/L), V represents the volume in liter, and M denotes the weight of the adsorbent (g).…”