Impact of NaOH Concentration on Deweaving of Cotton Fabric in Aqueous Solutions

In the past decade, there has been increasing attention paid to the recycling of cotton fabric waste. In the present study, different concentrations of sodium hydroxide (NaOH) ranging from 1 M to 4 M were used to thermomechanically deweave cotton fabric. The fabrics treated with 1 M NaOH and 2 M NaOH were partially deweaved, whereas those treated with 3 M NaOH and 4 M NaOH were completely deweaved. Fourier-transform infrared (FTIR) spectroscopy was applied to analyze the chemistry and structure of the cotton fabric. The FTIR spectra indicated that the structure of cotton fabrics treated with 1–2 M NaOH were similar to that of pristine fabric, while the presence of NaOH was observed. In the case of samples treated with 3–4 M NaOH, both the peak positions and the band intensities were changed, in addition to the formation of cellulose II. FTIR spectra for the recycled NaOH-treated cotton fabrics were compared, and no major structural changes were identified. A post-treatment with deionized (DI) water removed excess Na + ions, with the sample showing a similar molecular structure to that of the pristine material. These results suggest the feasibility of recycling aqueous NaOH for post-washing treatment as a new method for recycling cellulosic fabric waste.