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With regard to polyesters based on biobased 2,5-furandicarboxylic acid (FDCA), our work presents a new strategy, heteroatom substitution, to adjust the thermal and gas barrier properties. The effects of nonhydroxyl oxygen heteroatoms in the diols on the properties of FDCA-based polyesters were first investigated by a combination of an experiment and molecular simulation. The results demonstrated that the introduction of oxygen heteroatoms significantly influenced the thermal and gas barrier properties. As for the two model polymers with a very similar skeleton structure, poly­(pentylene 2,5-furandicarboxylate) (PPeF) and poly­(diethylene glycol 2,5-furandicarboxylate) (PDEF), their T g exhibited an obviously increasing order. Moreover, they showed similar thermal stability and thermal oxidative stability. Dynamic mechanical analysis, positron annihilation lifetime spectroscopy, and molecular dynamics simulation indicated that the gas barrier properties followed the sequence of PDEF > PPeF mainly due to the decreased chain mobility and smaller fractional free volume. In-depth analysis of the effects of heteroatom substitution has an important directive significance for the design and preparation of new high glass transition temperature or novel excellent gas barrier materials. Through the manipulation of different heteroatoms in the diols, the polyesters with varied properties can be expected.

This study investigates the photocatalytic degradation of acetaminophen (Ace) from synthetic wastewater by individual TiO 2 , TiO 2 /SiO 2 and/or WO 3 /TiO 2 /SiO 2 composite under UV-VIS illumination. To characterize changes in their morphology and crystal structures before and after treatment, Χ-ray diffraction (ΧRD), Fourier transform infrared spectroscopy (FTIR), DRS UV-VIS absorption spectra, Brunaer-Emmer-Teller (BET) and scanning electron microscopy (SEM) techniques were used. The effects of varying loading ratios of the WO 3 on the TiO 2 /SiO 2 composite for Ace degradation were studied. Operating parameters such as initial concentration, reaction time, dose of photocatalyst and pH were tested. Degradation by-products were also presented. It is found that the photodegradation performance of the WO 3 /TiO 2 /SiO 2 composite as a photocatalyst in this study could be enhanced by optimizing the loading ratio of the WO 3. About 3% (w/w) of WO 3 /TiO 2 /SiO 2 was found to improve the degradation of Ace from 33% to 95% at the same initial concentration of 5 mg/L. The resulting oxidation by-products included hydroquinone and 1,4-benzoquinone. Under the same conditions, the result of photocatalytic degradation by the 3% (w/w) of WO 3 /TiO 2 /SiO 2 composite was significantly higher (95%) than that by the individual TiO 2 /SiO 2 (42%) and/or by the TiO 2 alone (33%). Under optimized conditions (1.5 g/L; 3% (w/w) of WO 3 /TiO 2 /SiO 2 composite; pH 9; 4 h of reaction time), 95% of Ace removal with an initial concentration of 5 mg/L could be attained. However, the treated effluents still could not meet the discharge standard of less than 0.2 mg/L set by China's and US legislation. This indicates that further subsequent treatment like biological processes is still necessary for completing the removal of target pollutant from the wastewater samples.

This study investigates the technical feasibility of MWCNTs for acetaminophen (Ace) removal from synthetic wastewater in batch mode. To improve their removal performance, the surface of the MWCNTs was chemically modified with NaOH, HNO 3 /H 2 SO 4 , ozone and/or chitosan. The effects of pertinent parameters such as reaction time, dose, pH, and agitation speed on the Ace removal were evaluated. Their removal performance on Ace was compared to those of previous studies. The adsorption mechanisms of Ace removal by the MWCNTs are also presented. It is evident from this study that after chemical modification on its surface, the treated nano-adsorbent significantly enhanced Ace removal from wastewater. Among all types of those adsorbents, the ozone-treated MWCNT stands out for the highest Ace removal (95%) under the same initial Ace concentration of 10 mg/L. Their adsorption capacities, applicable to the Freundlich isotherm model, are listed as: ozone-treated MWCNT (250 mg/g) > chitosan-coated MWCNT (205 mg/g) > acid-treated MWCNT (160 mg/g) > NaOH-treated MWCNT (130 mg/g) > as-received MWCNT (90 mg/g). Although the ozone-treated MWCNT has the most outstanding performance in Ace removal, its treated effluent still could not meet the required effluent limit of less than 0.2 mg/L set by China's legislation. This suggests that further treatment using biological processes needs to be carried out to complement Ace removal from the wastewater samples.

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