Liang Zhou,Jie Zhou,Yicen Dong,Yangjie Wu,Zhangying Xi,Zixuan Lu,Juying Lei,Jinlong Zhang,Yongdi Liu
Collaborative treatment of pollutants is a promising approach for wastewater treatment . In this work, a covalent organic framework material (COFs) with an imine structure was synthesised by the Schiff base reaction, and photochemical tests showed good photochemical effects. It was used to explore the photocatalytic treatment of co-existing pollutants (heavy metal ions and antibiotics) and the performance of treating co-existing wastewater was investigated. The degradation performance of levofloxacin (LVX) and Cr(VI) was improved in the coexisting pollutants system, with the LVX degradation being 4.2 times more effective than that of the LVX solitary system. Moreover, this phenomenon was also observed in LVX/Ag(I), LVX/Fe(III), sulfadiazine/Cr(VI), norfloxacin/Cr(VI) and tetracycline/Cr(VI) systems. The analysis of active species suggesting that the synergistic promotion of photocatalytic oxidation-reduction systems was not only promoting from the improvement of simple charge separation, but it was also found that high-valent metal species can act directly in the oxidative decomposition of antibiotics. The interaction of pollutants and intermediates were rationally exploited and confirmed by control experiments and theoretical calculation. This conclusion helps us to re-examine the underlying mechanisms of photocatalytic synchronous oxidation and reduction reactions, simultaneously beneficial for the development of mixed pollutant control processes.
Yang Xu,Yongjian Xu,Wenhuan Deng,Hao Chen,Jianhua Xiong
Dialdehyde cellulose nanocrystals (DCNC) are defined as C2 and C3 aldehyde nanocellulose, which can be used as raw materials for nanocellulose derivatization , owing to the high activity of aldehyde groups. Herein, a comparative study in NaIO 4 pre-oxidation and synchronous oxidation is investigated for DCNC extraction via choline chloride (ChCl)/urea-based deep eutectic solvent (DES). Ring-liked DCNC with an average particle size of 118 ± 11 nm, a yield of 49.25 %, an aldehyde group content of 6.29 mmol/g, a crystallinity of 69 %, and rod-liked DCNC with an average particle size of 109 ± 9 nm, a yield of 39.40 %, an aldehyde group content of 3.14 mmol/g, a crystallinity of 75 % can be extracted via optimized DES treatment combined with pre-oxidation and synchronous oxidation, respectively. In addition, the average particle size, size distribution, and aldehyde group content of DCNC were involved. TEM , FTIR , XRD, and TGA results reveal the variation of microstructure, chemical structure, crystalline structure, and thermostability of two kinds of DCNC during extraction even though the obtained DCNC exhibiting different micromorphology , pre-oxidation, or synchronous oxidation during ChCl/urea-based DES treatment can be considered as an efficient approach for DCNC extraction.
Arsenite (As(III)) is more toxic and difficult to remove than arsenate (As(V)). In this study, an S-doped Cu-La bimetallic oxide (S-CuLaO) decorated with metal-organic framework (MOF) composite (S-CuLaO@UIO-66) was synthesized and applied for the adsorption of As(III). The maximum adsorption capacity of As(III) by S-CuLaO@UIO-66 was as high as 171 mg/g, which was much higher compared with other MOF compounds reported to date. The UIO-66 support improved the dispersion and reduced the size of the S-CuLaO particles, which increased the number of exposed adsorption reactive sites. Study of the mechanism revealed that the synchronous oxidation and adsorption significantly increased the removal of As(III). O 2 ∙ - was produced by the receiving electron from the dissolved oxygen from Cu(I) in S-CuLaO, which converted As(III) to As(V). Furthermore, the stability and reusability S-CuLaO@UIO-66 (without regeneration) was investigated at a low As(III) concentration (approximately 1000 µg/L) in deionized water and well water. The residual arsenic concentration ranged from 0.8 to 2.8 μg/L in deionized water and 3–58.2 μg/L in well water within 240 min during three cycles. Generally, this study suggests that combining an optimal oxide with a stable MOF is a promising approach for the fabrication of composite adsorbents.
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