Summary Microplastics (MPs) pollution in household wastewater and global aquatic systems has become an emerging issue and potential threat to marine life and human health. However, advanced technologies for efficient MPs control and purification remain largely underdeveloped. Herein, we present integrated carbocatalytic oxidation and hydrothermal (HT) hydrolysis of microplastics over magnetic spring-like carbon nanotubes. The robust carbon hybrids exhibited an outstanding MPs degradation performance by catalytic activation of peroxymonosulfate to generate reactive radicals. The spiral architecture and highly graphitic degree guaranteed the superb stability of the carbocatalysts in HT environment. The toxicity tests indicated that the organic intermediates from MPs degradation were environmentally benign to the aquatic microorganisms and can serve as a carbon source for algae cultivation. The outcomes of this study are dedicated to providing a green strategy by integrating state-of-the-art carbocatalysis and nanotechnology for remediation of MPs contamination in water.

Degradation of Cosmetic Microplastics via Functionalized Carbon Nanosprings

Transition metal (cerium and cobalt) doped γ-MnO2 (M-γ-MnO2, where M represents Ce, Co) catalysts were successfully synthesized and characterized. Cerium-doped γ-MnO2 materials showed ozone (O3) conversion of 96% for 40 ppm of O3 under relative humidity (RH) of 65% and space velocity of 840 L g–1 h–1 after 6 h at room temperature, which is far superior to the performance of the Co-γ-MnO2 (55%) and γ-MnO2 (38%) catalysts. Under space velocity of 840 L g–1 h–1, the conversion of ozone over the Ce-γ-MnO2 catalyst under RH = 65% and dry conditions within 96 h was 60% and 100%, respectively, indicating that it is a promising material for ozone decomposition. XRD and HRTEM data suggested that Ce-γ-MnO2 formed mixed crystals consisting of α-MnO2 and γ-MnO2 with specific surface area increased from 74 m2/g to 120 m2/g compared to undoped γ-MnO2, thus more surface defects were introduced. H2-TPR, O2-TPD, XPS, Raman, and EXAFS confirmed that Ce-γ-MnO2 exhibited more surface oxygen vacancies and surface defects, whi...

Oxygen Vacancies Induced by Transition Metal Doping in γ-MnO2 for Highly Efficient Ozone Decomposition.

Dyes are priority pollutants, commonly found at significant concentrations in textile effluents. The presence of dyes stuffs in wastewater can cause severe problems to aquatic life and human beings. Therefore, the removal of dyes from wastewater is important in order to minimize their hazardous effects on the environment. One way of removing dyes is to use nanosized manganese oxides (MnOs). To date, there has been much work reported on the use of nanosized MnOs as sorbents for dyestuffs. They are promising sorbents for commercial use due to their amorphous nature, high specific surface areas (SSA), mesoporous structure, and low to the moderate point of zero charge (pHPZC). This review summarizes the toxicity and recent advances for removing dyes from wastewater using nanosized MnO sorbents. The article also describes the various experimental parameters necessary for adsorption optimization, such as adsorption time, pH, initial dye concentration, amount of sorbent and temperature. Adsorption mechanisms investigated by various modeling approaches are also discussed. In particular, it was observed that much work has been reported on the use of birnessite and its composites for dye removal. There are many papers reporting on the use of MnO in batch mode dye removal, but very few that report on the use of MnO in continuous column removal systems. Therefore, there is still a considerable need for further research to develop effective and economical large scale MnO column systems for commercial use.

Removal of dye from polluted water using novel nano manganese oxide-based materials

A series of Na-OMS-2 catalysts was prepared by a facile solid-state reaction method. Their physiochemical properties were characterized, and the catalytic activity for ozone decomposition was evalu...

Enhancing Oxygen Vacancies by Introducing Na+ into OMS-2 Tunnels To Promote Catalytic Ozone Decomposition.

In this work, FeCo2O4 was prepared by a simple coprecipitation method and investigated as a heterogeneous Fenton catalyst. The influences of sodium dodecyl sulfate (SDS) on the structure, surface charge, electron transfer ability, and catalytic activity of FeCo2O4 were investigated. FeCo2O4–S prepared with SDS exhibited much higher catalytic activity for the degradation of methylene blue (MB) in aqueous solution than pure FeCo2O4, which can be attributed to its higher electron transfer ability. The adsorbed SDS accelerated the reduction of surface Fe3+ to Fe2+ by H2O2 and •O2–. The high concentration of surface Fe2+ on FeCo2O4–S during the reaction promoted the decomposition of H2O2 into •OH, which was the main active specie for the degradation of MB. Furthermore, SDS increased the adsorption capacity of the catalyst toward MB, thus facilitating the reaction between adsorbed MB and •OH generated on the catalyst surface.

Shengtao Xing

Papers

Hydrothermal synthesis and characterization of surface-modified δ-MnO2 with high Fenton-like catalytic activity