Volatile-Organic-Compound-Intercepting Solar Distillation Enabled by a Photothermal/Photocatalytic Nanofibrous Membrane with Dual-Scale Pores

Abstract

Solar distillation is emerging as a robust and energy-effective tool for water purification and freshwater production. However, many water sources contain harmful volatile organic compounds (VOCs), which can evaporate through the photothermal evaporators and be collected together with distilled water, or even be enriched in the distilled water. In view of the penetration of volatile organic compounds, herein, we rationally demonstrate a dual-scale porous, photothermal/ photocatalytic, flexible membrane for intercepting volatile organic compounds during solar distillation, which is based on a mesoporous oxygen-vacancy-rich TiO 2−x nanofibrous membrane (m-TiO 2−x NFM). The dual-scale porous structure was constructed by micrometer-sized interconnected tortuous pores formed by the accumulation of m-TiO 2−x nanofibers and nanometer-sized pores in the m-TiO 2−x individual nanofibers. Consequently, the membrane can sustainably in situ intercept VOCs by providing more photocatalytic reactive sites for collision (mainly by mesopores) and longer tortuous channels for prolonging VOC retention (mainly by micrometer-sized pores); thus, it results in less than 5% of phenol residual in distilled water. As a proof of concept, when the m-TiO 2−x NFM is employed to purify practical river water in an evaporation prototype under real solar irradiation, complex volatile natural organic contaminants can be effectively intercepted and the produced distilled water meets the drinking water standards of China. This development will promote the application prospects of solar distillation.

Defect‐Induced Self‐Cleaning Solar Absorber with Full‐Spectrum Light Absorption for Efficient Dye Wastewater Purification

“…Note that light absorption of the well‐designed H‐TiO 2− X /Cs X WO 3 composite surpassed that of the previous reported Ti‐related photothermal materials. [ 32,38,64 ]…”

“…The evaporation rate of H‐TiO 2− X /Cs X WO 3 was comparable to those of reported Ti‐related solar evaporators and multifunctional solar evaporators (Figure 6h). [ 26,27,30–33,35,36,64,67–72 ]…”

“…In contrast, the membrane offered many reactive sites and extended VOC retention, which led to a < 5% residual of phenol in purified water. [ 32 ] An O V ‐rich HNb 3 O 8 nanosheets aerogel has been used for solar steam generation and photodegradation of RhB. Complete degradation and negligible photodegradation of RhB were, respectively, observed for O V ‐rich HNb 3 O 8 nanosheets aerogel and bare aerogel.…”

Polymeric Membranes with Selective Solution‐Diffusion for Intercepting Volatile Organic Compounds during Solar‐Driven Water Remediation

“…These merits unambiguously indicate the feasibility of using MPS-PPy membranes for solar water purification with efficient VOC interception. Besides, compared with catalytic oxidation alternative methods, [80,81] the VOC interception based on solution-diffusion possesses the advantages of no need of expensive oxidants and no production of organic by-products.…”

Clean water generation through a multifunctional activated carbon-TiO2 interfacial solar distillation system

“…However, compared with other high-boiling-point contaminants (e.g., dye pollutants) studied in current published works, [19][20][21] the inuence of VOCs on solar distillation has rarely been studied, which may be of greater concern in the solar distillation process. To the best of our knowledge, only two studies 22,23 have recently explored the inuence of VOCs (using phenol solutions as source water) on clean water generation through solar-driven water evaporation. Shi et al introduced an oxidant-based method into a solar distillation process that showed a high ($98.2%) VOC removal efficiency.…”