Liangxin Xu

Mercury ion responsive wettability and oil/water separation.

A novel Hg(2+) responsive oil/water separation mesh with poly(acrylic acid) hydrogel coating is reported. The mesh can separate oil and water because of the superhydrophilicity of the poly(acrylic acid) hydrogel coating on the mesh, and switch the wettability based on the chelation between Hg(2+) and poly(acrylic acid) . The reversible change in oil contact angle of as-prepared mesh is about 149° after immersion in Hg(2+) solution. This mesh is an ideal candidate for oil-polluted water purification, especially for water that contains Hg(2+) contaminant.

Ultralight free-standing reduced graphene oxide membranes for oil-in-water emulsion separation

We report a facile and environmentally friendly route to fabricate ultralight free-standing RGO membranes. Such membranes are capable of separating multiple types of surfactant stabilized oil-in-water emulsions with oil droplets of nano/sub-micrometer size, as well as display high separation efficiency and excellent anti-fouling properties, making them highlighted alternatives for water remediation.

Biocompatibility evaluation of aniline oligomers with different end-functional groups

With the ever increasing interest in biomedical applications of aniline oligomers, carefully and systematically evaluating their biocompatibility is of significant importance. In this paper, aniline oligomers with different end-functional groups (tetramer terminated with gluocose (T–G), pentamer terminated with amino group (P–NH2) and pentamer terminated with carboxyl group (P–COOH)) were synthesized. Their cellular responses to adenocarcinomic human alveolar basal epithelial (A549) cells and human cervical carcinoma (HeLa) cells were investigated for the first time. To verify their potential for in vivo biomedical applications, the interactions between aniline oligomers and red blood cells (RBCs) were further examined. Results indicated that end groups of oligomers affected their cell response. Among all tested molecules, T–G showed the greatest cytotoxicity to both types of cells. Compared with HeLa cells, all oligomers exhibited better biocompatibility with A549 cells. Furthermore, the cell membrane of RBCs was still kept intact after incubation with aniline oligomers for over 4 h, indicating that the cytotoxicity of aniline oligomers was not due to the rupture of the cell membrane. We expect that these results could be helpful to understand the cytotoxicity of aniline oligomers and may give valuable instructions to design biocompatible aniline oligomers for biomedical applications.

Nonionic polymer cross-linked chitosan hydrogel: preparation and bioevaluation

A straightforward method to prepare nonionic polymer (polyacrylamide, PAM) cross-linked chitosan hydrogel has been developed. The chitosan–polyacrylamide (CS–PAM) hydrogel could be quickly obtained by simply mixing of chitosan and polyacrylamide solutions under very benign condition (room temperature, <30 s). The cytotoxicity and hemocompatibility of the CS–PAM hydrogel were subsequently investigated. Cells retained normal morphology even when the concentration of CS–PAM hydrogel in culture system was as high as 640 μg mL−1, indicating the CS–PAM hydrogel has minimal cytotoxicity to A549 and HeLa cells. Meanwhile, no hemolysis was observed after incubating the CS–PAM hydrogel with red blood cells for 6 h, further suggesting excellent biocompatibility of the hydrogel. Scanning electron microscopy images illustrated that the CS–PAM hydrogel can absorb red blood cells through the interaction between the protonated amine groups on chitosan and the negative charged residues on red blood cell membranes. Given its low cost, simple preparation, and excellent biocompatibility, this CS–PAM hydrogel might be a potential biomaterial for future healthcare and biomedical applications.

A fast and convenient cellulose hydrogel-coated colander for high-efficiency oil–water separation

A cellulose hydrogel was successfully prepared in alkali/urea solution using a freezing/melting method and was coated on nylon mesh. The as-prepared mesh was superhydrophilic in air with a water contact angle of 0° and superoleophobic under water with an oil contact angle above 150°. The hydrophobicity was well maintained in various aqueous phases, which reflects its stability under severe conditions. The mesh was effective in oil–water separation because water quickly permeated through the mesh while oil was obstructed. Separation can be efficiently performed without auxiliary power. A colander was also fabricated with the mesh that can be used to scoop waste oil floating on water.

Magnetically Recoverable Efficient Demulsifier for Water‐in‐Oil Emulsions

A magnetically recoverable and efficient demulsifier is shown to demulsify surfactant-stable water-in-oil emulsions rapidly. Ferroferric oxide (Fe3 O4 ) particles are firstly coated by amorphous silicon dioxide (SiO2 ), and further functionalized with a commercial dodecyltrimethoxysilane solution (KH-1231). Owing to their paramagnetic properties, the demulsifier particles can be easily recovered with a magnet. Upon addition of demulsifier to emulsions and subsequent sonification, the supernatant becomes completely transparent and no droplets are observed in the micrographs. It was also demonstrated that this demulsifier is effective for emulsions prepared with a variety of oils. Moreover, magnetically recovered demulsifier can be recycled after simple treatment without any decline of efficiency. This work presents a feasible approach for demulsifying water-in-oil emulsions, and has potential value in industry.

Fabrication of Silica Nanospheres Coated Membranes: towards the Effective Separation of Oil-in-Water Emulsion in Extremely Acidic and Concentrated Salty Environments.

A superhydrophilic and underwater superoleophobic surface is fabricated by simply coating silica nanospheres onto a glass fiber membrane through a sol-gel process. Such membrane has a complex framework with micro and nano structures covering and presents a high efficiency (more than 98%) of oil-in-water emulsion separation under harsh environments including strong acidic and concentrated salty conditions. This membrane also possesses outstanding stability since no obvious decline in efficiency is observed after different kinds of oil-in-water emulsions separation, which provides it candidate for comprehensive applicability.

Polymer Decorated Filter Material for Wastewater Treatment: In-situ Ultrafast Oil/water Emulsion Separation and Azo Dye Adsorption

Aiming to realize the wastewater treatment of various pollutants simultaneously, a dual-functional poly(ether amine)-polydopamine (PEA-PDA)-modified filter material was fabricated in this work for in situ separation of stable oil-in-water emulsion and adsorption of anionic azo dyes. PEA and PDA could be copolymerized via the Michael addition reaction on a polyurethane sponge substrate firmly. The as-prepared filter shows superhydrophilic and underwater superoleophobic wettability. After being squeezed in a glass tube, the material could separate different kinds of stabilized oil-in-water emulsions with high flux and efficiency. Besides, the PEA-PDA copolymer endows the material with the ability to adsorb large amounts of anionic azo dyes during the separation of emulsions with good adsorption capacity. Moreover, adsorbed dyes in the filter material could be easily desorbed in base aqueous solution and the whole process is conducted under gravity without external aid. This dual-functional material shows great potential for the application in industrial field because of its ability for the complex wastewater treatment.