Transpiration-prompted Photocatalytic Degradation of Dye Pollutant with AuNPs/PANI Based Cryogels

Incautious discharge of organic dyes such as methyl orange (MO) has produced serious pollution to the environment, calling for the efficient techniques to remove them with retaining the green world. The photo-catalytic degradation of organic dyes is promising among the developed techniques. Thus, a strategy based on transpiration-prompted photocatalytic degradation of dye pollutant under sunlight is put forward. Aniline (ANI) is graft-polymerized onto poly(acrylamide- co-N -4-aminophenylacrylamide) (PAAm) cryogel embedded with gold nanoparticles (AuNPs, diameter: 4–10 nm). The obtained cryogels integrated with AuNPs and PANI inside PAAm matrix (AuNP@PAAm- g -PANI) have been structurally explored based on the chemical composition and the phase/porous morphology. SEM and TEM observation shows that PANI and AuNPs are uniformly distributed in PAAm matrix. Since the macro-porosity of cryogel, hydrophilicity of PAAm and photo-thermal activity of PANI, PAAm-g-PANI cryogels without AuNPs can have a photo-thermal evaporation rate of water at 1.63 kg·m −2 ·h −1 . As a comparison, AuNP@PAAm- g -PANI cryogels with AuNPs exhibit higher one at 2.20 kg·m −2 ·h −1 , suggesting the promotion of AuNPs to photo-thermal evaporation. Meanwhile, PANI appreciatively assists AuNPs to display higher catalytic ability for the oxidative degradation of MO. Therefore, the removal of MO from water is obviously prompted by the water transpiration under sunlight with AuNP@PAAm- g -PANI cryogels, whose rate constant can reach to 0.320 h −1 , being three folds of that for the sole absorption of MO. This transpiration-prompted photocatalytic degradation provides a fascinating route to eliminate organic pollutants and obtain pure water from wastewater simultaneously with sustainable sunlight energy.