Dongxue Yang,Lingfeng Li,Binling Chen,Shuxian Shi,Jun Nie,Guiping Ma
In order to improve the removal ability of chitosan (CS) to heavy metal ions , in this study, rich amino-functionalized CS electrospun membranes have been prepared. During the efficient synthesis, poly (glycidyl methacrylate) (PGMA) and polyethylenimine (PEI) were sequentially grafted on the surface of CS electrospun membrane. The success of introduction of amino-group on the CS were confirmed by X-ray diffractometer (XRD), attenuated total reflection-fourier transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The ability of remove heavy metal ions (Cr(VI), Cu(II) and Co(II)) of the as-prepared membrane (CS-PGMA-PEI) was investigated. The adsorption equilibrium of the heavy metal ion solutions was rapidly established in 60 min. Adsorption kinetics analysis reveals that the adsorption process of CS-PGMA-PEI electrospun membrane was dominated by a Pseudo-second-order model. Its adsorption isotherm can be described by the Langmuir model. The maximum adsorption capacities calculated by Langmuir model were 138.96, 69.27 and 68.31 mg g −1 for Cr(VI), Cu(II) and Co(II), respectively. The adsorption ability of CS-PGMA-PEI electrospun membrane toward metal ions was found in an order of Cr(VI) > Cu(II) > Co(II). CS-PGMA-PEI membrane also exhibited a good reproducibility and stability. Our study may provide a way to synthesize membranes for water purification .
Liya Zhou,Xucong Luo,Jiaojiao Li,Li Ma,Ying He,Yanjun Jiang,Luyan Yin,Liya Gao
The meso-molding three-dimensionally ordered macroporous alumina (3DOM/m-Al) was synthesized via a dual-templating approach (polystyrene (PS) colloidal crystals as hard template and triblock copolymer P123 as soft template) with hydrous aluminum isopropoxide as precursor. The obtained 3DOM/m-Al was characterized, and the results showed that 3DOM/m-Al had ordered macropores ( ca. 300 nm in diameter) with wormhole-like mesopores, relatively high surface areas (338.1 m 2 /g), large pore volumes (0.4030 cm 3 /g) and tunable pore sizes. The amino functionalized 3DOM/m-Al by aminopropyltriethoxysilane (APTES) was activated by glutaraldehyde and used as support for the immobilization of three different commercial enzymes (Lipase B from Candida antarctica (CALB), penicillin G acylase (PGA) and nitrile hydratase (NHase)). The result of confocal laser scanning microscopy (CLSM) indicated that the enzyme was successfully immobilized onto glutaraldehyde-activated NH 2 -3DOM/m-Al. The effect of the immobilized conditions on the specific activity of enzymes was investigated. Compared with free enzymes, the immobilized enzymes exhibited enhanced thermal stability. The three immobilized enzymes (CALB@NH 2 -3DOM/m-Al, PGA@NH 2 -3DOM/m-Al and NHase@NH 2 -3DOM/m-Al) were applied for the synthesis of palmitic acid, 6-aminopenicillanic acid (6-APA) and acrylamide, respectively. After recycling 10 times, CALB@NH 2 -3DOM/m-Al, PGA@NH 2 -3DOM/m-Al and NHase@NH 2 -3DOM/m-Al retained approximately 76%, 87% and 52% of their initial activities, respectively, indicating that the immobilized enzymes had good operational stability. Therefore, this work documented herein provides a versatile platform for enzyme immobilization with several inherent advantages.
The novel SP/IL/AMS composite membrane doped with amino-functionalized mesoporous silica (AMS) was successfully prepared. Sulfonated poly ether ether ketone (SPEEK, SP) was used as the polymer matrix and the ionic liquid (IL) was N -ethylimidazolium trifluoromethanesulfonate (EIm[Tfo]). Its properties were compared with SP/IL/NMS composite membrane doped with non-functionalized mesoporous silica (NMS). Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the components in the composite membrane were bound by intermolecular forces. In addition, an acid-base interaction was formed between -NH 2 in AMS and -SO 3 H in SPEEK. The acid-base pair is beneficial to proton conduction. The anhydrous proton conductivity of SP/IL/3-AMS-7.5 composite membrane is about 4 times higher than that of the SP/IL/NMS-7.5. In addition, the good interfacial compatibility between AMS and polymer matrix is conducive for creation continuous proton transfer channel. Thermogravimetric analysis (TG) showed that all composite membranes were stable at 270 °C. The leaching of IL data indicated that IL can be effectively retained due to the presence of -OH and -NH 2 on the NMS and AMS surfaces. The SP/IL/AMS composite membrane could be used in proton exchange membrane fuel cells under medium temperature and anhydrous conditions.
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