Abstract
Tight ultrafiltration (TUF) membranes with high performance have attracted more and more attention in the separation of organic molecules. To improve membrane performance, some methods such as interface polymerization have been applied. However, these approaches have complex operation procedures. In this study, a polydopamine (PDA) modified MoS2 (MoS2@PDA) blending polyethersulfone (PES) membrane with smaller pore size and excellent selectivity was fabricated by a simple phase inversion method. The molecular weight cut-off (MWCO) of as-prepared MoS2@PDA mixed matrix membranes (MMMs) changes, and the effective separation of dye molecules in MoS2@PDA MMMs with different concentrations were obtained. The addition amount of MoS2@PDA increased from 0 to 4.5 wt %, resulting in a series of membranes with the MWCO values of 7402.29, 7007.89, 5803.58, 5589.50, 6632.77, and 6664.55 Da. The MWCO of the membrane M3 (3.0 wt %) was the lowest, the pore size was defined as 2.62 nm, and the pure water flux was 42.0 L m−2 h−1 bar−1. The rejection of Chromotrope 2B (C2B), Reactive Blue 4 (RB4), and Janus Green B (JGB) in aqueous solution with different concentrations of dyes was better than that of unmodified membrane. The separation effect of M3 and M0 on JGB at different pH values was also investigated. The rejection rate of M3 to JGB was higher than M0 at different pH ranges from 3 to 11. The rejection of M3 was 98.17–99.88%. When pH was 11, the rejection of membranes decreased with the extension of separation time. Specifically, at 180 min, the rejection of M0 and M3 dropped to 77.59% and 88.61%, respectively. In addition, the membrane had a very low retention of salt ions, Nacl 1.58%, Na2SO4 10.52%, MgSO4 4.64%, and MgCl2 1.55%, reflecting the potential for separating salts and dyes of MoS2@PDA/PES MMMs.
Highlights
Tight ultrafiltration (TUF) membranes have received increasing attention from water treatment and resource recovery in recent years [1]
In the treatment of dye wastewater, the TUF membrane of mesoporous shows more beneficial effects than nanofiltration (NF) membranes, because of the relative lower operating pressure required by the TUF process, and because of the pore size characteristics of TUF membranes
Da), Reactive Blue 4 (RB4) (637.43 Da), and Janus Green B (JGB) (511.06 Da) were acglycol polyethylene glycols (PEGs) (2000, 4000, 6000, 8000, 10,000 Da), Chromotrope 2B (C2B) (513.37 Da), Reactive quired from Sigma Aldrich
Summary
Tight ultrafiltration (TUF) membranes have received increasing attention from water treatment and resource recovery in recent years [1]. The blending method can be performed by introducing DA or PDA to the membrane casting solution directly [12] This method improves the hydrophilicity, permeability, and antifouling performance of the membrane, increases the porosity and pore size of the membrane. PDA-encapsulating nanoparticles were blended into the polymer mixed matrix to improve the membrane performance. Sianipar et al found that the incorporation of PDA-coated multi-walled carbon nanotubes (MWNTs) could increase the membrane permeability without a reduction of selectivity as well as improve the antifouling properties, and enhanced mechanical strength was found by adding. Molybdenum disulfide (MoS2 ) is a graphene-like material with a relatively large area It performs well in RO, NF, and UF membrane and improves the permeation without sacrificing retention [19–21]. The morphology structure, surface characteristics, membrane thermostability, dyes separation, and salts filtration performance of the prepared membranes were investigated. Membranes 2021, 11, 96 ogy structure, surface characteristics, membrane thermostability, dyes separation, and salts filtration performance of the prepared membranes were investigated
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