A novel strategy to upcycle the waste masks: Synthesis of chelating adsorbent and application in heavy metal removal

The COVID-19 pandemic has brought about increasing demand of face masks, however, due to the inadequate disposal, it has caused great environmental problems. In this study, we try to recycle these wastes to fabricate chelating materials for the potential application in heavy metal removal from wastewater. Surface characteristics of the prepared amine-modified polypropylene (AMP) adsorbent were identified by advanced methods. The introduced amino groups endowed AMP a more basic and hydrophilic surface, which facilitated electrostatic attraction with cations in acidic to neutral conditions. Moreover, batch experiments showed the adsorption of heavy metals onto the AMP was pH dependent and followed pseudo-second-order kinetic model and Langmuir adsorption isotherm model, and the theoretical adsorption capacities were 58.275, 62.500 and 58.207 mg/g for Pb 2+ , Cu 2+ and Zn 2+ , respectively. In particular, the prepared AMP can be regenerated for 10 cycles with relatively stable heavy metal absorption capacity. Chemical adsorption was proposed as the main adsorption mechanism, as N worked as electron donor to form complex with metal ions, and metal salt crystal growth was also observed on AMP surface. The favorable adsorption capacity and reusability of AMP demonstrated the potential of upcycling the waste masks in wastewater treatment.