Utilising the microstructure of chemically and thermally activated waste textiles for noise attenuation in an urban Australian context

This study considers the suitability of end-of-life cotton textiles as a precursor for activated carbon fibre (ACF) cloth for noise attenuation. The study presents a materials transformation and valorisation technique to increase circularity of waste textiles, which is supported by strong end markets and increasing demand. Thermal and chemical parameters were modified to identify the preferable settings for maximising the surface area of the activated carbon fibre cloth. The surface area was tested using Brunauer-Emmett-Teller (BET) Analysis. The least amount of phosphoric acid (H3PO4) on the sample yielded the highest surface area when comparing textile to acid dosage ratios of 1-1, 1-2, 1-3 and 1-4. Varying the water content in the 1-1 ratio had little effect on the surface area but did affect the structure. The textile - acid - water ratio of 1-1-4 was preferable to 1-1-2, as more of the textile structure remained intact under the naked eye and under the Scanning Electron Microscopy (SEM). Samples transformed under a temperature of 850 °C had a higher surface area than samples transformed at 650 °C and 950 °C, which were 1900 m2/g, 1500 m2/g. and 1600 m2/g respectively. To maximise noise attenuation, multi-layer activated carbon fibres were created by layering the textiles prior to chemical and thermal transformation processes. By increasing the scale of production, the surface area was reduced. However, the multi-layer ACF yielded promising results even with a modest surface area of approximately 1300 m2/g. The analysis showed that the ACFs were superior to broad spectrum acoustic foams for higher frequency sound desipite being one fifth of the corresponding thickness. The findings from this study are promising for applications requiring a very thin noise attenuating barrier. This advanced material could increase circularity of waste textiles in Australia and reduce the impact of noise pollution in urban environments.