Alkaline Hydrolysis of Polyester in the Presence of Ionic Liquids

Abstract

The alkaline hydrolysis of polyester fabric in NaOH solution in the presence of several 1-alkyl-3-methylimidazolium bromine ionic liquids (ILs), CnMImBr (n=8, 12, 14, 16) was examined in comparison to the use of cetyltrimethyl ammonium bromide (CTAB) as an accelerant. The weight loss of polyester fabric was found to be greatly dependent on the concentrations of ILs and the length of alkyl groups in ILs. C14MImBr and C16MImBr exhibited good catalytic actions. The use of C16MImBr as an accelerator could endow polyester fabrics with slightly higher weight loss in comparison with CTAB. In the presence of C16MImBr, the activation energy of polyester hydrolysis reaction was slightly higher than that for the use of C14MImBr as a catalyst. In summary, the CnMImBr with long carbon chain can be employed as the novel accelerator for the weight reduction process of polyester fabrics.

Sustainable Alkaline Hydrolysis of Polyester Fabric at Low Temperature

“…The alkali concentration is lower, but also the presence of the aromatic ring in the pyridinium group reduces the surfactant adsorption [59]. The results obtained with CTAB (cetyl trimethylamonium bromide) in terms of weight loss are similar to those obtained with HDTMAC at high temperatures when CTAB was used in NaOH with lower concentration (10 g cm −3 ) at 95 • C [24]. Considering that previous researches using cationic surfactants as accelerators were at temperatures above 90 • C. Similar results for weight loss at 60 • C using HDTMAC as when CTAB was used as an accelerator were found when CTAB was used with a much higher concentration of NaOH (10%) [26].…”

“…Hydrolyzed fabrics have better wettability and dyeability and a silk-like appearance and luster. However, hydrolysis also results in pitting corrosion (etching) with a negative impact on fabric strength [3,[9][10][11][12][13][14][15][22][23][24][25][26]29,39]. Furthermore, it requires a high amount of sodium hydroxide, high energy, and water consumption.…”

“…Furthermore, it requires a high amount of sodium hydroxide, high energy, and water consumption. Alkaline hydrolysis is usually performed in 4-20% KOH and NaOH at temperatures higher than 100 • C (130-140 • C) for more than 1-2 h. The alkaline hydrolysis performed in addition to different cationic surfactants and polymers [6][7][8][9][10][11][12][13][14][15][19][20][21][22][23][24][25][26] can accelerate this process. It was found that some cationic surfactants and polymers accelerate the process (but not all).…”

“…Recently, ionic liquids have been used to reduce the weight of polyester, up to 20% [22][23][24][25][26]. Dong et al [24] investigated alkaline hydrolysis in the presence of different 1-alkyl-3-methylimidazolium bromine ionic liquids (ILs) with different numbers of C-atoms (i.e., CnMImBr (n = 8, 12, 14, 16)) and compared them to cetyltrimethylammonium bromide (CTAB) as accelerators.…”

“…Recently, ionic liquids have been used to reduce the weight of polyester, up to 20% [22][23][24][25][26]. Dong et al [24] investigated alkaline hydrolysis in the presence of different 1-alkyl-3-methylimidazolium bromine ionic liquids (ILs) with different numbers of C-atoms (i.e., CnMImBr (n = 8, 12, 14, 16)) and compared them to cetyltrimethylammonium bromide (CTAB) as accelerators. It was found that CnMImBr with a long carbon chain can be used as a novel accelerator, which can be explained by the higher adsorption capacity of polyester for the ILs or cationic surfactants with longer carbon chains.…”