Chromium containing leather trimmings valorization: Sustainable sound absorber from collagen hydrolysate intercalated electrospun nanofibers.

Developing value-added material from industrial waste is one of the sustainable ways of recycling solid waste produced from the leather industry. Noise which makes a considerable negative impact in the day to day life of people needs immediate attention where the sound absorbers play a vital role. Nanofibers can be used as sound absorbers due to their properties like porosity and high surface area. In this study, collagen hydrolysate extracted from waste leather trimmings was utilized to produce multilayer hybrid sound-absorbing material. Collagen hydrolysate was electrospun along with polyvinyl alcohol (PVA) and the layer was sandwiched between polyacrylonitrile (PAN) nanofibrous layers. The hierarchical structure of the composite is more porous on outer layers than medium porous inner collagen hydrolysate- PVA layer. The hybrid material was characterized using various experimental techniques and the sound absorption was measured using two-microphone impedance tube method. From acoustic measurements, it was revealed that the composite showed improved sound absorption in the frequency range of 800-2500 Hz due to its varying pore size. Hence, the leather trimmings as a component of sound-absorbing material creates an innovative solution for discarded leather waste and they can be used in practical applications like room acoustics.