Accelerated Degradation of Microplastics at the Liquid Interface of Ice Crystals in Frozen Aqueous Solutions

Abstract

Microplastics (MPs) are one of the emerging contaminants in environmental media, and they have raised great concern because they are resistant to degradation and persist in ecosystems. Although numerous advanced technologies have been developed, suitable technologies are still lacking for degradation of widespread MPs in the natural environment. We have discovered that MPs can be degraded exceptionally rapidly in frozen environments. Taking polystyrene (PS) as an example, its degradation rate in ice (À 20 °C) is surprisingly competitive to most artificial technologies. PS particles are trapped and squeezed to achieve excited state ( 3 PS*) in the narrow space of the liquid layer between ice crystals, which further react with the highly concentrated dioxygen to selectively produce singlet oxygen ( 1 O 2 ). The 1 O 2 boosts PS oxidation in the liquid layer thus further causing accelerated degradation at freezing temperature. This finding offers a highly efficient pathway for degradation of MPs and it sheds light on an unusual MPs disposal mechanisms in nature.

Boosting the growth and aggregation of sulfide nanoparticlesviaregulating heterogeneous nucleation for enhanced sedimentation

“…The hydrophilicity/hydrophobicity determines the Interaction between the metal sulfide particles and the solvent (water). 31 We assessed the hydrophilic/hydrophobic properties of CuS particles by measuring the contact angle. The contact angles for CuS without stirring and seeding, CuS with only stirring, CuS with only seeding, and CuS with stirring and seeding are 49.9°, 52.42°, 62.53° and 71.84°, respectively (Fig.…”

Artificial photosynthesis bringing new vigor into plastic wastes

“…[45][46][47][48] Among these, advanced oxidation process as remediation technology is implemented with the goal of plastics elimination via generating reactive oxygen species, such as •OH, O 2 −• , and 1 O 2 . [49][50][51][52] For instance, Tian et al 53 developed a low-temperature frozen strategy to remove PS. In this case, the freezing condition was favorable for the dissolution of dioxygen, which benefited the formation of radical species (i.e., 1 O 2 and •OH), thus dramatically promoting the removal efficiency of PS.…”

Biodegradable plastics in the marine environment: a potential source of risk?

“…In the marine environment, temperature, pH, and salinity change in a certain range, and ultra-high temperatures could accelerate the oxidative degradation [76] and abiotic hydrolysis [30] of plastics, while ultralow temperatures might cause frozen-accelerated degradation [77] . However, for biodegradation, a temperature within a suitable range is needed for both the microbial growth on the surface of BPs and the reaction rate of enzymes [78] .…”