A sustainable and low pollutive strategy for the recycling of waste hot-gas filter bags: The development of filter reinforced epoxy composites

Abstract

The fast accumulation of waste hot-gas filter bags has become a growing public concern considering its difficulty in degradation, severe pollution elicited by landfill and incineration, high energy consumption during burning or complicated recycling and low margin of regenerative products. Herein, we provide a new feasible recycling strategy by directly employing the cleaned polyphenylene sulfide (PPS) /polytetrafluoroethylene (PTFE) waste filters in their fabric state as the reinforcement of epoxy composites. Merely two layers of filters could produce composites with flexural strength and modulus sufficient for many applications and the additional carbon fiber fabric (CFF) covering could further strengthen the composites (295 to 1010 % increments). The filters also showed a bonding promotion function between CFF and polymethacrylimide foam in lightweight composites. After hydrothermal treatment, the composites reinforced by the recycled filters displayed 97.2 % and 90.9 % retention rate for flexural strength and modulus, respectively. Compared to the pure epoxy, the composites could achieve a limiting oxygen index of 27.6 %, and display 24 % decline in thermal energy release and 20.0 to 31.0 % reduction in the generation rate of combustion products, indicating strengthened flame-retardancy. With shortened processes and elevated properties of composites, the approach established for recycling waste filters in this work showed far-reaching implications in carbon emission reduction, environmental pollution diminishing and commercialization potential.

Keywords: Epoxy composites; Flame-retardant; PPS/PTFE; Recycling; Waste hot-gas filter.