Visible light-promoted anti-biofouling performance of cellulose acetate membrane for reverse osmosis desalination

Sea water desalination is regarded as a major solution that could alleviate the water scarcity problem. Reverse osmosis (RO) is typically employed to recover fresh water from sea and brackish water via economical means. RO membrane fouling remains a critical issue restricting their widespread application. In this work, a tertiary thiophenal quaternary ammonium salt-based antibacterial agent was covalently reacted with cellulose acetate (CA) to obtain contact-active antibacterial quaternized CA-RO membrane (QCA-RO). The membrane was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, water contact angle testing, and X-ray diffraction spectroscopy. The obtained QCA-RO membrane displayed good antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus and had bactericidal rates of 99 % in the presence of visible light. Results showed that embedding the quaternary ammonium salt did not cause any significant changes to the morphology, mechanical performance, and thermal stability of the RO membrane. The method described in this work not only produces QCA-RO membranes with good anti-biofilm performance but also presents great potential in seawater desalination.

Synthesis and application of a novel polyurethane nanoemulsion bearing coumarin derivative as a "turn-on" fluorescence sensor toward Hg2

A novel polyurethane (PU-co-HCCA) nanoemulsion bearing coumarin derivative (HCCA) was synthesized as a "turn-on" fluorescent probe and used to modify filter paper, and its sensing properties were investigated. Results showed that PU-co-HCCA nanoemulsion exhibited high selectivity and excellent sensitivity toward Hg²⁺ over other metal ions, and possessed excellent fluorescence quantum yields of 0.976, ppb-levels detection limits of 1.61 ppb and large Stokes shifts of 101 nm. Meanwhile, as an application example of as-prepared PU-co-HCCA nanoemulsion, a Hg²⁺ test paper was prepared by modifying filter paper with PU-co-HCCA nanoemulsion, and results indicated that the test paper is portable and convenient and has a wide working pH range. We believe that the PU-co-HCCA nanoemulsion and the modified filter paper can provide a new design principle for the application of fluorescence sensors for metal ions including Hg²⁺.

Simple preparation of a durable and low-cost load-bearing three-dimensional porous material for emulsion separation

Superhydrophobic MR–C composites were used for the separation of water-in-oil emulsions. Under a load of 500 N with a reciprocating wear, the contact angle was kept at 146 ± 2°. The oil-in-water emulsion can still be separated efficiently.