Prospects of TiO2-based photocatalytic degradation of microplastic leachates related disposable facemask, a major COVID-19 waste

Abstract

COVID-19 is one of the serious catastrophes that have a substantial influence on human health and the environment. Diverse preventive actions were implemented globally to limit its spread and transmission. Personnel protective equipment (PPE) was an important part of these control approaches. But unfortunately, these types of PPE mainly comprise plastics, which sparked challenges in the management of plastic waste. Disposable face masks (DFM) are one of the efficient strategies used across the world to ward off disease transmission. DFMs can contribute to micro and nano plastic pollution as the plastic present in the mask may degrade when exposed to certain environmental conditions. Microplastics (MPs) can enter the food chain and devastate human health. Recognizing the possible environmental risks associated with the inappropriate disposal of masks, it is crucial to avert it from becoming the next plastic crisis. To address this environmental threat, titanium dioxide (TiO2)-based photocatalytic degradation (PCD) of MPs is one of the promising approaches. TiO2-based photocatalysts exhibit excellent plastic degradation potential due to their outstanding photocatalytic ability, cost efficiency, chemical, and thermal stability. In this review, we have discussed the reports on COVID-19 waste generation, the limitation of current waste management techniques, and the environmental impact of MPs leachates from DFMs. Mainly, the prominence of TiO2 in the PCD and the applications of TiO2-based photocatalysts in MPs degradation are the prime highlights of this review. Additionally, various synthesis methods to enhance the photocatalytic performance of TiO2 and the mechanism of PCD are also discussed. Furthermore, current challenges and the future research perspective on the improvement of this approach have been proposed.

Photocatalytic Removal of Polyester Polyurethane, and Polyethylene Microplastics via ZnO-Fe-Mg-C Nanocomposite to H2

“…In addition, increasing the Fe dopant content exhibited an increase in the number of concentric rings. These originated from the Fe-doped ZnO/C/Mg nanoparticles b size reduction, with the self-aggregation of some bulk layers, [58], [59], [60], [61]. The hydrolysis reaction of polyester polyurethane and polyethylene to H2 was carried out within a 36hour reaction time using Fe-doped samples containing 2% ZnO/Fe/Mg/C nanocomposite a and 4% ZnO/Fe/Mg/C nanocomposite b.…”

“…The H2 productions were extremely high since polyethylene carbon bonds were lower than that of polyester polyurethane, [59], [60], [61]. ZnO/Fe/Mg/C nanocomposite a, with a Fe content of 2%, exhibited higher H2 production than the other.…”

“…When polyester polyurethane conversion is not completed; A metabolite residue was recovered, indicating that polyester polyurethane polymers consist of a metabolite with a lower molecular weight. After use, the ZnO/Fe/Mg/C nanocomposite catalyst can be easily recovered by centrifugation, and reused in other catalytic experiments under the same conditions; this shows a slight decrease in H2 production of 3% (data not shown), [47], [60], [61], [62], [63].…”

Photocatalytic degradation of different types of microplastics by TiOx/ZnO tetrapod photocatalysts

“…Consequently, photodegradation processes including the effect of illumination and the effects of a number of different photocatalysts on degradation/chemical changes of different plastics have been investigated in recent years [ [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] ], and the results have been summarized in Table S1 . The degraded plastics include polyolefins, such as polyethylene (PE) and polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) polyethylene terephthalate (PET), polyamide fibers, and poly(methylmethacrylate) [ 1 , 8 , 9 , 12 ].…”

“…There are many possible candidates for photocatalyst materials. Metal oxides, such as ZnO [ 27 , 28 ] and TiO 2 [ [20] , [21] , [22] , [23] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] ], have been among commonly investigated photocatalysts for microplastics degradation [ 4 , 7 , 9 ]. While complete degradation of PE under UV-C light (254 nm) was reported for TiO 2 , negligible degradation of PE was obtained under UV-A (365 nm) and visible illumination [ 20 ].…”