An efficient method to recycle and reuse meta-aramid from used dust filter bags

The annual replacement of a large number of used dust filter bags generated as industrial waste has seriously polluted the environment and caused waste of resources. The meta-aramid filter media is a typical representative of them. In this work, a complete and efficient process for the recovery and reuse of meta-aramid filter bag was proposed, which mainly included three stages, i.e., pretreatment, dissolution recovery and reuse. Firstly, the feasibility of recycling the pretreated used meta-aramid filter media was demonstrated by FT-IR, XRD and SEM characterization. Then the optimum dissolution method was selected for the recovery of used filter materials. The effects of dissolving temperature, type and concentration of solubilizer on dissolution time, solubility and dissolution products were systematically investigated. 110 °C, 4 wt% LiCl as solubilizer and DMAc as solvent were selected as the preferred conditions. The method was successfully used to achieve 100% dissolution recovery of used meta-aramid material with a concentration of 25 wt%, and the whole recovery process was environmentally friendly. Moreover, the recovered meta-aramid solution was used to prepare meta-aramid films by phase inversion method. The performance tests and characterization confirmed that the obtained films had good thermal stability, mechanical properties, flame retardancy and insulation properties. The whole recycling process not only alleviated the threat of waste filter bags to the environment, but also achieved high quality reuse of meta-aramid filter material and had great application prospects.