Soil environment on earth contains a variety of ions, which are expected to play a vital role in the biodegradation of plastics discarded in the environment. In this work, poly(butyleneadipate- co -terephthalate) (PBAT) is employed as a model biodegradable plastic to study the specific ion effects on the enzymatic degradation of polyester plastics. The results show that the specific ion effects on the enzymatic degradation rate of the PBAT films and on the catalytic rate constant for the enzymatic hydrolysis of the ester bonds are strongly dependent on temperature and ionic strength. Both the enzymatic degradation rate and catalytic rate constant decrease following the trends Na + > K + > Ca 2+ and Cl − > SO 4
2− > NO 3
− for cations and anions, respectively, indicating that the ion-specific enzymatic degradation of the PBAT films is closely correlated with the specific ion effects on enzymatic hydrolysis of the ester bonds. Our study shows that the specific ion effects on the enzyme activity can be understood by taking into account the ion-specific cation-anion interaction, ionic dispersion force, salting-out effect and salting-in effect. This study of specific ion effects on the enzymatic hydrolysis of the ester bonds and the resultant enzymatic degradation of the PBAT films would offer us a new clue to develop new biodegradable, environmentally friendly synthetic plastics.
The chlorine resistance is recognized as one of the crucial and essential properties of membranes in water treatment field. In this study, β-cyclodextrin (β-CD) with abundant hydrophilic hydroxyl groups as aqueous phase monomer and trimesoyl chloride (TMC) as organic phase monomer were utilized to fabricate the polyester thin film composite (TFC) nanofiltration (NF) membranes by interfacial polymerization (IP) method. The optimized β-CD polyester TFC membrane with 1.8 wt% β-CDs in aqueous phase was immersed in harsh chlorine environment (10000 ppm NaClO aqueous solution) up to 96 h and exhibited the steady water flux and dye rejection, manifesting the outstanding chlorine-resistant performance of β-CD polyester TFC membranes. The sodium hypochlorite cleaning experiments showed that NaClO was effective to remove the deposited and adsorbed foulants onto the β-CD polyester TFC membranes. Therefore, the superior chlorine resistance of β-CD polyester TFC nanofiltration membranes would find promising potential applications in water treatment processes.
Abstract Copolymers were synthesized from acrylate monomers and ladder-shaped polysilsesquioxanes (LPSQ) using free radical polymerization, and the copolymers were coated on polyethylene terephthalate (PET) films by the lift-off impregnation method. The nanosized SiO 2 sols with different particle sizes were prepared by sol-gel method, and then the nanosized SiO 2 sols were coated on the surface modified PET film to construct a moth-eye-like anti-reflection coating by using the layer-by-layer self-assembly method. The structure and composition of LPSQ and modified acrylic resin copolymer were characterized by infrared spectroscopy and X-ray diffraction, and the transmittance/haze tester and UV spectrophotometer were used to test the performance of the anti-reflection coating, which could reach 94.0% compared with 89.2% of the matrix pure PET film. Thermogravimetric analysis showed that the thermal decomposition temperature of the LPSQ-modified copolymer material was higher than that of the pure acrylate copolymer.
Polyester thin film composite (PE-TFC) membranes featuring excellent chlorine-resistant property hold grand promise in seawater desalination and wastewater treatment. However, the low reactivity of alcohol or phenolic hydroxyl groups with acyl chloride groups usually leads to the formation of a relatively loose PE network, resulting in undesirable salt rejection. Preparing high-performance PE-TFC membranes remains a daunting challenge. In this study, we propose a thermal-facilitated interfacial polymerization (TFIP) approach to fabricate PE-TFC membranes with high desalination performance. The elevated temperature promoted the diffusion of glucose monomers across the water/heptane interface and then facilitated the reaction rate between glucose and TMC during interfacial polymerization (IP), resulting in the formation of PE layer with a higher cross-linking density compared to that fabricated via conventional IP. The PE membrane prepared via TFIP exhibited a superior ion rejection of 99.5% for Na2SO4 and high water permeance up to 16.1 L m−2 h−1 bar−1, outperforming all the polyester membranes with similar rejection in literature. The resultant PE-TFC membrane displayed unprecedented chlorine resistance (960 000 ppm h) and maintained separation efficiency after exposed to sodium hypochlorite solution (1000 ppm) for 36 days. Polyols including sucrose, raffinose and β-CD were also utilized as monomers, confirming the universality of the TFIP approach for facile preparation of high-performance desalination membranes.
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