Re-use of waste cotton textile as an ultrafiltration membrane

Abstract

Textile industry produces millions of tons of waste annually, which is predominantly incinerated or landfilled. Cotton textile comprises a quarter of total textile production, and although being renewable, its production is highly chemical- and water-intensive, rising the need for effective waste cotton textile recycling. This study presents an investigation whether it is possible to utilize waste cotton textile as a cellulose source for the fabrication of cellulose membranes. The effect of casting thickness and cellulose concentration on the prepared membranes’ performance was studied. Membranes cast from 2 wt.% casting solutions exhibited the highest permeabilities of 1.11 and 3.09 m3/(m2·s·Pa) for 300- and 150-microns casting thickness, respectively, but poor adhesion stability and low retention. Membranes cast from solutions of higher concentrations (5, 6, and 7 wt.%) resulted in membranes with more stable performance. The permeability values for 300-microns membranes were in the range of 0.27 – 0.39 m3/(m2·s·Pa) and for 150-microns 0.51 – 0.67 m3/(m2·s·Pa). The retention values of these six membranes were relatively close to each other, showing 80 – 92% retention of polyethylene glycol (PEG) 35 kDa. Three most promising membranes (5, 6, and 7 wt.% cast at 150-microns) were additionally characterized, showing negative zeta potential within -23 – -35 mV range at pH 7 and contact angles of very hydrophilic material (14 – 16°). Overall, the results showed that very hydrophilic ultrafiltration membranes having attractive permeability and retention properties can be made from textile waste. 1 m2 of cotton bed linen is enough to produce approximately 20 m2 of cellulose membrane.