The Fate of Microplastics, Derived from Disposable Masks, in Natural Aquatic Environments.

This paper mainly reviews the fate of microplastics, released from used face masks, in the water environment. Through previous experiments, the amount of fiber microplastics released from used face masks into aqueous environments was not negligible, with the maximum microplastics releasing amount reaching 10,000 piece·day-1 for each mask. Microplastic derived from these masks often occurred in the shape of polymeric fibers that resulted from the breakage of the chemical bonds in the plastic fibers by the force of water flow. The potential contact forces between microplastics (originating from face masks) with other pollutants, primarily encompass hydrophobic and electrostatic interactions. This critical review paper briefly illustrates the fate of microplastics derived from disposable face masks, further devising effective strategies to mitigate the environmental impact of plastic particle release from the used personal protective equipment.

The potential of green biochar generated from biogas residue as a heterogeneous persulfate activator and its non-radical degradation pathways: Adsorption and degradation of tetracycline.

Advanced oxidation aided by sulfate radicals (SO4-) is an effective option for the treatment of refractory pollutants from aqueous solutions. In this work, a metal-free biochar catalyst was prepared using pyrolyzed biogas residue as the raw material. The biogas residue carbon (BRC) obtained at 800 °C showed excellent catalytic activity and adsorption capacity for the removal of tetracycline (TC) with 97.9% of removal efficiency. Such performance is accounted for by the rich pores and accelerated electron transformability conferred by its defect structure with the crucial role of pyrolysis temperature in regulating catalyst properties. The BRC-800/peroxymonosulfate (PMS) system worked predominantly through non-radical pathways with high stability/recyclability without being interfered by organic/inorganic compounds in an actual water environment. The exceelent removal performance is also supported by the kinetic reaction rate of the BRC-800/PMS system as estimated to be 0.03017 min-1. This work provides a simple and effective path for modifying biogas residue waste for versatile applications.

A novel chitosan-vanadium-titanium-magnetite composite as a superior adsorbent for organic dyes in wastewater.

In this research, a novel chitosan (CS)-vanadium-titanium-magnetite (VTM) composite was designed and synthesized. The interaction between CS-VTM and Congo red (CR) dye conformed to a pseudo-second-order model to support the potent involvement of chemisorption. The effects of adsorbent dosage, reaction temperature, and initial solution pH on adsorption of CR were investigated. Approximately 99.1% of CR (100 mg/L) was adsorbed at a CS-VTM dose of 2.0 g/L or above, while such a reaction was favored at temperatures of 65 °C and pH of 6.0. Thermodynamically, the adsorption of CR proceeded spontaneously (ΔG < 0) above 35 °C. According to scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, and zeta potential analysis, its adsorption on CS-VTM can be attributed to electrostatic attraction and hydrogen bonds. The prepared CS-VTM exhibited superior adsorption performance on removal of CR as evidenced by significantly large partition coefficient of 108.3 mg g-1 µM-1 (equilibrium adsorption capacity of 62.2 mg/g at CR dose of 100 mg/L). Overall, the CS-VTM proved to be a promising and environmentally friendly adsorbent for the highly efficient and effective removal of organic dyes among the comparable sorbents studied to date.