The effect of catalyst on pyrolysis behavior of cotton and PEs for waste clothes reusing

Abstract

In recent years, the amount of waste clothes has been increasing. And the recycling of the waste clothes would be necessary for material cycles. A new method for separating blended fibers is required, because the separating of fibers is difficult to be tangle fibers in clothes. Recent reports indicate that the addition of an iron-based catalyst in the pyrolysis improves the decomposition rate of cotton, and the TBT (Titanium Butoxide Tetramer) catalyst improves the pyrolysis decomposition of PEs. Consequently, a new method of separating single fiber from blended fibers by catalytic pyrolysis was proposed. In this study, thermo-gravimetric (TG) analysis and a lab scale pyrolysis experiment of cotton and PEs were conducted by using two types of catalysts, FeCl2 and TBT. These catalysts were selected to understand the fundamental phenomena of cotton and PEs pyrolysis. The results showed that the FeCl2 catalyst made the pyrolysis starting temperature of cotton lower and pyrolysis rate increased. Whereas the TBT did not affect the pyrolysis behavior of cotton and PEs. The FeCl2 was the most effective catalyst for controlling the pyrolysis temperature and separating the fibers during pyrolysis. In a lab scale catalytic pyrolysis experiment with actual cotton and PEs, the cotton was decomposed to 90 % of its mass by pyrolysis. While the PEs was not so decomposed, and 90 % of PEs was remained at 633 K pyrolysis temperature. As the verification of thermal effect on the PEs residue, FTIR analysis revealed that the surface functional groups of the PEs raw material were not affected by pyrolysis. This study demonstrated that the catalytic pyrolysis would accelerate the decomposition of only cotton, while PEs could be remained and potentially reused as a raw material.

Keywords

• waste clothes
• pyrolysis
• catalyst
• residue
• recycle