Enzymatic Recycling of High-Value Phosphor Flame-Retardant Pigment and Glucose from Rayon Fibers

Abstract

Viscose (also known as Rayon) filaments are obtained from regenerated cellulose and are used in many different sectors mainly as reinforcement material in tires and other cord applications and in the clothing industry. The incorporation of a phosphor-containing pigment imparts flame-retardancy properties to these fibers, which then can be used as part of personal protection textiles delivering wear comfort. There are no recycling strategies for these materials being brought to landfills or chemically degraded since incineration is difficult because of their flame retardancy. In this study, an enzyme-based strategy for the recovery of glucose and of the phosphor pigment without altering their chemical structures was developed as a circular economy solution. Rayon fibers were completely hydrolyzed by a cellulase preparation while 98% of the glucose (reducing sugar assay and HPLC analysis) and more than 99% of the flame-retardant pigment present in the fibers was recovered. The recovered pigment was analyzed via 1H, 13C, and 31P NMR, and the purity >95% was comparable to that of the commercially available pigment. The recovered glucose was successfully used as carbon source for ethanol production by Saccharomyces cerevisiae while the recycled phosphor pigment was reused in viscose filament production leading to similar mechanical properties like those measured for virgin fibers. This work presents an environmentally friendly recycling strategy of functional rayon fibers for the recovery of the two major components, namely, glucose and the pigment.

High Throughput Screening for New Fungal Polyester Hydrolyzing Enzymes

“…As fungal plant pathogens, N. cinnabarina_F55 are well known to produce extracellular enzymes capable of degrading cell wall components such as cutin, since they are essential during the invasion of the host. This is in good agreement with our previous results indicating that cutinases hydrolyze very efficiently synthetic polyesters (Pellis et al, 2016a;Weinberger et al, 2017b;Vecchiato et al, 2018). Enzyme production by N. cinnabarina_F55 was studied in the presence of natural substrates or plant cells (Purdy and Kolattukudy, 1973;Eddine et al, 2001;Hawthorne et al, 2001).…”

“…Apart from the essential function in organisms, esterases and lipases are among the most widely used biocatalysts in the chemical industry (Wohlgemuth, 2010) and can potentially enable the recovery of the polymer building blocks. These building blocks can be used as carbon source for the fermentative production of products such as ethanol or lactic acid (Pellis et al, 2016b;Vecchiato et al, 2018). However, enzymatic hydrolysis of these polyesters is rather slow and hence more efficient enzymes would be required in order to implement an enzymatic recycling industry.…”

Highly Selective Enzymatic Recovery of Building Blocks from Wool-Cotton-Polyester Textile Waste Blends

“…Inversely, samples with lower amounts of such material have shown slightly lower amounts of released sugar (Figure 4). This can be explained by the presence of higher oligosaccharides as previously reported by Vecchiato et al [19].…”

“…The glucose released from enzymatic hydrolysis of cellulose was used for ethanol production from Saccharomyces cerevisiae . An overnight pre-culture was incubated at 28 °C and 150 rpm in Yeast Extract–Peptone–Dextrose Medium (YPD) media (1% yeast extract, 2% peptone, 2% d-glucose) [19]. Then, the pre-culture as collected by centrifugation washed 3 times and re-suspended in 10 mL of mQ-H 2 O.…”

“…Enzymes, due to their high specificity, would allow step-wise recovery of the components of blended materials under environmentally friendly conditions [14,15]. Although enzymatic hydrolysis of individual components has been demonstrated by us and other groups [16,17,18,19], the potential of enzymes for stepwise recovery of building blocks from blends has not been demonstrated so far. Hence, in this study, step-wise enzymatic hydrolysis of cellulose/wool/polyester blends was investigated.…”