4-Dimethylaminopyridine Promoted Interfacial Polymerization between Hyperbranched Polyesteramide and Trimesoyl Chloride for Preparing Ultralow-Pressure Reverse Osmosis Composite Membrane

Abstract

We have presented a concept of ultralow-pressure reverse osmosis membrane based on hyperbranched polyesteramide through interfacial reaction promoted by pyridine derivate. In this strategy, a key catalyst of 4-dimethylaminopyridine, which can both eliminate the steric hindrance of acyl transfer reaction and facilitate the phase transfer in interfacial polymerization, is adopted to drive the formation of a thin film composite membrane from the hyperbranched polyesteramide and trimesoyl chloride. The results of the characterization demonstrate that a dense, rough, and hydrophilic active layer with a thickness of about 100 nm is formed when the 4-dimethylaminopyridine catalyst is used. The salt rejections for Na2SO4, NaCl, and MgSO4 of the as-prepared composite membrane are higher than 92%, especially for Na2SO4 with 98% rejection. The water fluxes reach about 30-40 L·m(-2)·h(-1) even at an operation pressure of 0.6 MPa. The membrane exhibits good chlorine-resistance ability but poor resistance abilities to acidic and alkaline solutions in the physical-chemical stability experiment. It is also found that the resultant membrane possesses excellent separation performance for PEG-200, showing a promising way to separate small organic molecules from water.

Hyperbranched polymers: advances from synthesis to applications

“…Using 4-dimethylaminopyridine (DMAP) as the catalyst, trimesoyl chloride (TMC) and hyperbranched polyesteramide (HPEA) took part in an interfacial polymerization to generate a reverse osmosis membrane. 521 This composite membrane (thickness of B100 nm) exhibited a high salt rejection rate, e.g. Na 2 SO 4 rejection was up to 98% and NaCl and MgSO 4 rejections were 492% with water fluxes of around about 30-40 L m À2 h À1 and a pressure of 0.6 MPa.…”

“…Up till now, HPs have been widely used as diverse membranes, such as in nanofiltration membranes for water softening or water treatment, [519][520][521][522][523] proton exchange membranes for fuel cells, [524][525][526] gas separation membranes for chemical engineering [527][528][529][530] and antifouling/antibacterial membranes for bioapplications, [531][532][533] etc.…”

Reverse osmosis desalination: A state-of-the-art review

“…However, the use of PTC requires mixed solvent system in the organic phase due to its limited solubility in hexane. Qin et al [269] developed novel TFC membranes from interfacial reaction between hyperbranched polyesteramide (HPEA) and TMC with or without 4-dimethylaminopyridine (DMAP) in the aqueous phase. Without DMPA, the membrane performance in terms of water flux and salt rejection was extremely poor.…”

Aromatic Polyamide Reverse-Osmosis Membrane: An Atomistic Molecular Dynamics Simulation

“…Aromatic PA thin-film membranes offer water permeability of 3.5 × 10 –9 m Pa –1 s –1 with salt rejection of over 99.6% . The current challenge is to further enhance water flux of RO PA membranes without compromising selectivity. , Membrane separation performance is highly correlated with membrane morphology and structure. − Further investigations of the local structure and water diffusion inside the PA membrane at the microscopic level will facilitate the design of new PA membrane with improved efficiency. While recent experimental efforts have allowed improved characterization of PA thin films, − it is still a challenge to probe atomistic/molecular details in thin films around 100 nm …”