Huiying Bai, Panpan He, Liang Hao, Ning Liu, Zifen Fan, Bingyu Chen, Ran Niu*, Jiang Gong*. 

Waste-treating-waste: From waste polyester to metal-organic framework nanorod for synergistic interfacial solar evaporation and sulfate-based advanced oxidation process. 

Chemical Engineering Journal (2023) Accept (IF2022 = 16.774)

Catalytic conversion of waste plastics into semiconductive metal-organic framework (MOF) kills two birds with one stone, since it not merely offers promising possibility to realize freshwater production and water decontamination through interfacial solar evaporation and photocatalysis, but also advances upcycling of waste plastics. Nevertheless, exploiting synergistic photothermal-photocatalysis materials from recycled plastics remains a challenge. Herein, we report a facile solvothermal method of waste poly(ethylene terephthalate) bottles for the massive production of Co-MOF nanorod and construct a dual-functional Co-MOF/carbon nanotube (CNT) solar evaporator integrated with advanced oxidation process for simultaneous wastewater purification and freshwater production. Firstly, we prove that the evaporator owns high sunlight absorption due to the presence of CNT, super-hydrophilicity, and low heat conductivity, which endow it with fine photothermal conversion capability and reduced vaporization enthalpy. Benefiting from the above advantages, Co-MOF/CNT evaporator displays a high evaporation rate of 2.25 kg m^-2 h^-1 under 1 kW m^-2 illumination, when treating tetracycline (TC)-polluted water, along with good mechanical property, high flexibility, long-term stability, and high scalability. Secondly, based on the results of COMSOL and density functional theory calculation, the localized solar heat from CNT and rich open cobalt sites of Co-MOF nanorod are proved to play a synergistic effect in the activation of peroxymonosulfate to generate various reactive oxidation species. Thereby, the dual-functional evaporator achieves a superb TC degradation activity. Lastly, an outdoor device is designed for freshwater generation and catalytic decomposition of TC. The daily freshwater production amount is 4.5 kg m^-2, and the TC degradation efficiency is 93.1%. This study not merely advances the upcycling waste plastics into useful products, but also offers a sustainable platform to wastewater purification via a waste-treating-waste strategy.