Based on the accidental
discovery, a
linear-phase change energy storage material (PCESM) could be designed
by encapsulating phase change materials with hollow fiber membranes
(HFMs). Using HFM as a carrier for PCESM served two outstanding benefits.
First, both the hollow portion and the membrane wall of the HFM can
be utilized to encapsulate the phase change material, which is more
advantageous than the other carrier materials. Second, as the HFM
is a flexible fibrous polymer carrier, a flexible woven PCESM can
be prepared, and hence, the characteristics that can be woven into
a net expand the application range of this kind of PCESM. There are
limited reports on polyvinylidene fluoride (PVDF) HFM as carriers
for PCESM. In this work, PVDF HFM prepared via two different methods
was employed as carriers to encapsulate paraffin. Hence, two different
PCESMs were prepared, and the two materials were compared and characterized.
The significance of this work is in enriching the carrier selection
process for PCESM, and these findings can provide novel ideas for
the design of future PCESM.
Membrane fouling remains a major barrier to membrane separation, particularly obvious in polymer membranes. Dopamine (DA) is of great value as a precursor for conjugation hydrophilic molecules. In this study, PP hollow fibrous membranes were first modified by DA to form a layer of polydopamine (PDA) coating. Then taurine and glycidol were introduced respectively with assisted by PDA reactive layer, the prepared membranes corresponding to PP-T and PP-G membranes, respectively. PP and the modified PP membranes were confirmed by a thorough membrane characterization of ATR-FTIR, XPS, and FESEM measurements. The hydrophilic properties and permeability were measured by water contact angle (WCA) and permeation flux test. BSA was used to as model protein to evaluate the antifouling properties of the membranes. The results showed that taurine and glycidol were successfully introduced onto the membrane surface. The WCA of PP-T and PP-G membranes can be reduced to 328 and 268, and the flux recovery ratio increased around 90.6% and 89.8%, respectively. Based on the experimental results, taurine and glycidol effectively improved the hydrophilic and anti-fouling performance of PP membrane.
A hydrophilic compound, taurine, was investigated as an additive in the interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC) to prepare thin-film composite (TFC) membranes. The resulting membranes were characterized by X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy. The morphology and hydrophilicity of the membranes were investigated through scanning electronic microscopy and water contact angle measurements. The separation performance of the TFC membranes was investigated through water flux and salt rejection tests. The protein-fouling resistance of the films was evaluated by water recovery rate measurements after the treatment of bovine serum albumin. The membrane containing 0.2 wt % taurine showed the best performance of 92% MgSO 4 rejection at a flux of 31 L m 22 h 21 and better antifouling properties than the PIP-TMC membranes. An appropriately low concentration of taurine showed the same MgSO 4 rejection as the PIP-TMC membranes but a better fouling resistance performance.
Boron removal remains a major barrier to water purification, it is important to develop a specialized adsorption membrane for boron removal. By means of a simple and effective method, a hydrophilic membrane for boron removal with a polyhydroxy functional group on the surface was prepared. Firstly, a polysulfone (PSF) membrane was modified by co-depositing polyethyleneimine (PEI) with dopamine (DA) in one-step to produce amine-rich surfaces, then the DA/PEI-functionalized membranes were reacted with glycidol, with the prepared membranes corresponding to PSF-PDA/PEI membranes and PSF-diol membranes. The prepared membranes were characterized by water-uptake, FTIR, (X-ray photoelectron spectroscopy) XPS, (Field emission scanning electron microscope) FESEM, and zeta potential measurements. The hydrophilicity of the membrane was characterized by the static water contact angle (WCA) test. In addition, we systematically studied the impact of initial boron concentration, chelating time, and pH value on boron removal performance. The results showed that the PSF-diol membrane had strong hydrophilicity with a WCA of about 38°. The maximum adsorption capacity of boron appeared to be 1.61 mmol/g within 10 min at a boron concentration of 300 mg/L. Adsorption kinetics showed that saturation adsorption can be achieved in minutes at the initial concentration of 5 mg/L, which is beneficial to a rapid filtration process.
Efficient selective separation of low molecular weight dye/salt system is of great significance for promoting the development of membrane technology in the field of wastewater treatment. In this study, a loose nanofiltration membrane (LNF) was fabricated for the desalination of dye wastewater through a facile method. Firstly, styrene‐co‐maleic anhydride (SMA) containing anhydride group was added to PES membrane by blending, then polyethylene imide (PEI) was grafted onto the membrane surface by the reaction between amino group and anhydride group. Finally, the unreacted NH2 on the membrane surface were used for secondary cross‐linking with glutaraldehyde (GA) and ethylene glycol diglycidyl ether (EGDE) to obtain GA‐NF and EGDE‐NF membranes. Results showed that nanofiltration membranes with narrow pore size distribution and uniform structure are obtained. Compared with the aldehyde group in GA, the epoxy group in EGDE monomer has higher reactivity and hydrophilicity, which reacts with the amine group of PEI molecule to form hydrophilic hydroxyl group. Therefore, the water flux of EGDE‐NF membrane was about 20% higher than that of GA‐NF membrane, and the rejection of CR, AF, and EBT dyes was increased to more than 99%. Through chemical treatment of acid and alkali, both GA‐NF and EGDE‐NF membranes showed excellent separation performance stability.
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