Membrane technology can minimize spread of viruses in the environment during pandemics, however, its efficiency is highly limited by biofouling. In the current study, a composite membrane composed of commercial membrane material, poly(vinylidene fluoride) (PVDF), and thermo-responsive attapulgite (t-ATP) was developed. The t-ATP was synthesized by surface modification of attapulgite (ATP) nanofiber with poly( N -isopropylacrylamide) (PNIPAM). t-ATP acted as a nucleating seed to expedite crystallization of PVDF and as a hydrophilic modifier to enhance the wetting performance of membrane. The tensile strength, elongation, and permeance of membrane increased with increase in t-ATP content without compromising pore structure. PNIPAM chains in t-ATP were swollen or shrunken with the change in temperature, thus releasing adhesion between membrane and biofoulants. The modified membrane exhibited superior biofouling resistance performance compared with the pristine PVDF membrane owing to the hydrophilic property of t-ATP and the stretchable chains on its surface. Notably, 89% of biofouling on membrane surface was easily removed through a simple temperature-change coupling ultrasonic cleaning process. High performance of the PVDF/t-ATP membrane indicates its potential application for high-efficient biological wastewater treatment.
Jiawen Wang,Ruoshan Lei,Shilong Zhao,Feifei Huang,Degang Deng,Shiqing Xu,Huanping Wang
Rigorous temperature measurement employed to characterize physic-chemical state has compelled scientists to explore more novel materials for contactless optical thermometry, which must overcome the drawbacks of low sensitivity and poor signal discriminability. Here, a novel dual-mode optical thermometer La 2 ZnTiO 6 : Bi 3+ /Eu 3+ is designed, prepared and characterized via XRD , XPS , EPR, SEM, EDS , PL spectra and decay time. Under 350 nm excitation, the energy transfer process from Bi 3+ to Eu 3+ allows the samples to demonstrate adjustable multi-color emissions. The temperature-dependent emission spectra display that the luminescence intensity of Bi 3+ ions decreases quite faster than that of Eu 3+ ions with temperature, leading to a significant chromaticity shift (∆E = 224 ×10 −3 in 293–473 K) visible to naked eyes. Based on fluorescence intensity ratio of Eu 3+ versus Bi 3+ (FIR = I Eu /I Bi ), the sample shows the maximum relative sensitivity (S r ) of ~1.50% K −1 at 293 K and excellent signal discriminability. Meanwhile, the 5 D 0 → 7 F 2 transition of Eu 3+ ions shows a thermal-responsive lifetime with the optimal S r of 1.23% K −1 at 573 K. This work suggests that the La 2 ZnTiO 6 : Bi 3+ /Eu 3+ double perovskite phosphor has a great potential for dual-mode optical thermometry, being beneficial to obtain precise, sensitive and reliable temperature detection.
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