Enhanced photocatalytic degradation of organic contaminants in water by highly tunable surface microlenses.

Photocatalysis is one of the dominant technologies used to enhance the efficiency of water decontamination with light-based treatments. However, the effectiveness of photocatalysts is usually limited by the irradiation conditions and the properties of the water matrix. In this work, we have demonstrated the capability of surface microlenses (MLs) as a clean technology for more efficient photocatalytic water decontamination. Random or ordered surface MLs were fabricated from simple polymerization of nanodroplets produced in a solvent exchange process. Both random microlenses (MLR) and microlenses array (MLA) could enhance the photocatalytic degradation efficiency (η) of four representative organic pollutants, including methyl orange (MO), norfloxacin (NFX), sulfadiazine (SFD), sulfamethoxazole (SMX), spiked in ultra-pure water, synthetic natural water, or real river water. By controlling the conditions of light treatment, η could be enhanced by up to 402%. The effectiveness of surface MLs was validated under both visible LED light and simulated solar light and for two photocatalysts zinc oxide (ZnO) and titanium dioxide (TiO 2). By reducing the concentration of the photocatalysts from 100 to 5 mg/L and the intensity of irradiation intensity from 1 Sun to 0.3 Sun, our findings suggest that the enhancement factor by MLs was higher at lower catalyst concentration, or at lower light intensity. Based on optical simulations and experimental results, we demonstrated that surface MLs optimize the light distribution and promote the formation of active species, which results in the enhancement of η. The use of MLs may serve as a novel strategy to improve the photocatalytic degradation of micropollutants, especially in places where the available light source is weak, such as indoors or in cloudy regions. Synopsis: MLs-enhanced photocatalysis degradation of organic contaminants in different water matrices. [Display omitted] • Surface MLs enhance photocatalytic degradation efficiency by up to 402%. • Green and highly tunable fabrication method of surface MLs. • Mechanisms of MLs-enhanced photocatalytic degradation with 3D optical simulations. • More improvement of degradation by MLs with less catalysts or weaker irradiation. • Verify the feasibility of MLs in improving decontamination in complex water matrix. [ABSTRACT FROM AUTHOR]