Poly[acrylate-co-amide] network composite via photopolymerization for organic solvent nanofiltration separation

Polyfunctional Arylamine Based Nanofiltration Membranes with Enhanced Aggressive Organic Solvents Resistance

Organic solvent nanofiltration (OSN) membranes with high separation performance and excellent stability in aggressive organic solvents are urgently desired for chemical separation. Herein, we utilized a polyfunctional arylamine tetra-(4-aminophenyl) ethylene (TAPE) to prepare a highly cross-linked polyamide membrane with a low molecular weight cut-off (MWCO) of 312 Da. Owing to its propeller-like conformation, TAPE formed micropores within the polyamide membrane and provided fast solvent transport channels. Importantly, the rigid conjugated skeleton and high connectivity between micropores effectively prevented the expansion of the polyamide matrix in aggressive organic solvents. The membrane maintained high separation performance even immersed in N,N-dimethylformamide for 90 days. Based on the aggregation-induced emission (AIE) effect of TAPE, the formation of polyamide membrane can be visually monitored by fluorescence imaging technology, which achieved visual guidance for membrane fabrication. This work provides a vital foundation for utilizing polyfunctional monomers in the interfacial polymerization reaction to prepare high-performance OSN membranes.

Preparation of a Solvent-Resistant Nanofiltration Membrane of Liquefied Walnut Shell Modified by Ethylenediamine

N,N-dimethylformamide (DMF) has excellent chemical stability and is widely used as an aprotic polar solvent. In order to reduce production costs and reduce pollution to the surrounding environment, it is necessary to recycle and reuse DMF. Previous research has found that the thin film composite nanofiltration membrane prepared from liquefied walnut shells exhibited a high rejection rate in DMF, but relatively low permeance and mechanical strength. In order to increase permeance without compromising the separation performance, ethylenediamine (EDA) is used as a modifier to graft onto the structure of liquefied walnut shell through the Mannich reaction. Then, modified liquefied walnut shell as an aqueous monomer reacts with trimesoyl chloride (TMC) via the interfacial polymerization method on the EDA-crosslinked polyetherimide (PEI) membrane. The results show that the permeance of the prepared membrane is significantly improved by an order of magnitude, demonstrating a rejection rate of 98% for crystal violet (CV), and a permeance of 3.53 L m-2 h-1 bar-1 in DMF. In conclusion, this study reveals the potential of utilizing liquefied walnut shells as raw materials for preparing high-performance separation membranes and demonstrates that surface modification is a feasible approach to enhance permeance of membranes without sacrificing the rejection rate.

Fabrication of Organic Solvent Nanofiltration Membrane through Interfacial Polymerization Using N-Phenylthioure as Monomer for Dimethyl Sulfoxide Recovery

To recover dimethyl sulfoxide, an organic solvent nanofiltration membrane is prepared via the interfacial polymerization method. N-Phenylthiourea (NP)is applied as a water-soluble monomer, reacted with trimesoyl chloride (TMC) on the polyetherimide substrate crosslinked by ethylenediamine. The results of attenuated total reflectance-fourier transform infrared spectroscopy and X-ray electron spectroscopy confirm that N-Phenylthiourea reacts with TMC. The membrane morphology is investigated through atomic force microscopy and scanning electronic microscopy, respectively. The resultant optimized TFC membranes NF-1NP exhibited stable permeance of about 4.3 L m−2 h−1 bar-1 and rejection of 97% for crystal violet (407.98 g mol−1) during a 36 h continuous separation operation. It was also found that the NF-1NP membrane has the highest rejection rate in dimethyl sulfoxide (DMSO), and the rejection rates in methanol, acetone, tetrahydrofuran, ethyl acetate and dimethylacetamide(DMAc) are 51%, 84%, 94%, 96% and 92% respectively. The maximum flux in the methanol system is 11 L m−2 h−1 bar−1, while that in acetone, tetrahydrofuran, ethyl acetate and DMAc is 4.3 L m−2 h−1 bar−1, 6.3 L m−2 h−1 bar−1, 3.2 L m−2 h−1 bar−1, 4.9 L m−2 h−1 bar−1 and 2.1 L m−2 h−1 bar−1, respectively. It was also found that the membrane prepared by N-Phenylthiourea containing aromatic groups has lower mobility and stronger solvent resistance than that of by thiosemicarbazide.

Fabrication of Poly(amide-co-ester) Solvent Resistant Nanofiltration Membrane from P-nitrophenol and Trimethyl Chloride via Interfacial Polymerization

P-nitrophenol (PNP), a refractory hazardous substance, has not been efficiently utilized so far. In this paper, PNP is used as a membrane modification material for preparing poly(amide-co-ester) composite nanofiltration membrane. An organic solvent nanofiltration (OSN) membrane was prepared via interfacial polymerization reactionby using PNP and trimethyl chloride (TMC) on a ethylenediamine (EDA) crosslinked polyetherimide substrate. The results of ATR-FTIR and XPS show that interfacial polymerization occurs among with PNP and TMC and the terminal amine groups on the ethylenediamine crosslinked -PEI support forming a poly(amide-co-ester) toplayer. The NF-1PNP membrane maintained stable DMF performance permeance of 2.2 L m−2 h−1 bar−1 and rejection of 98% for Rose Bengal red (RB 1017.64 g mol−1) in 36 h continuous separation process. Furthermore, the average pore diameter of the two membranes including NF-1PNP and NF-1.25PNP, which is 0.40 and 0.36nm, respectively. This study not only provides a good way for the preparation of OSN membrane, but also provides a good demonstration for the comprehensive utilization of PNP and other toxic and harmful pollutants.