Textile waste conversion into valuable products for environmental abatement.

A. L. CUKIERMAN; M. E. RAMOS; P. R. BONELLI

Nano-engineered Materials for Textile Waste Remediation, Environmental Footprints and Eco-design of Products and Processes

Springer Nature Singapore Pte Ltd

Año: 2023; p. 1 - 225

Thermochemical conversion of scraps from two 100% cellulosic textiles of different specific weight, denim, regenerated cellulose, and from a mixture of cellulose (37%) and polyester (73%) fibres, is investigated. Thermal degradation of the scraps under flowing N2, as assessed by thermogravimetric analysis over the temperature range 25–800 °C, shows quite similar behavior patterns, the differences depending on textiles composition and processing, except for the sample with polyester fibres. Conversion of the textile scraps into activated carbon cloths (ACCs) by chemical activation with solutions of 10 wt% concentration H3PO4 acid at pre-established conditions attains yields between 15% and 40%, the sample derived from the mixture containing polyester leading to the lowest value, likely due to polymer hydrolysis. The ACCs show BET surface areas up to 1200 m2 g-1, and porous structures with prevalence of micropores (< 2 nm). Thermogravimetric analysis of selected acid-impregnated textile scraps attests noticeable modifications induced by the acid with activation course, likely responsible for changes in reactions mechanisms that lead to porous development. Besides, yields and physicochemical characteristics of the ACCs arising from denim and regenerated cellulose scraps with 5 wt% concentration solutions of several chemicals are highly dependent on the compound used as activating agent. Ammonium chloride and phosphoric acid lead to denim-based ACCs with the highest yield and maximum porous development, respectively. For the regenerated cellulose scraps, boric and phosphoric acids promote essentially microporous ACCs, while those obtained with phosphate salts and ammonium citrate exhibit larger pores development. Comparison of the ACCs produced from denim and regenerated cellulose scraps with phosphoric acid and ammonium citrate in similar conditions shows that those obtained from the latter present a more developed porous structure. Besides, the denim-based ACCs obtained with ammonium chloride have the best ability in nitrate uptake from dilute solutions, attaining removal levels higher than 80%, followed by the ammonium citrate-derived ACCs. Their effectiveness is in line with the point of zero charge of these ACCs of basic character, attributed to the presence of surface nitrogen containing functionalities. In turn, the ACCs derived from the regenerated cellulose scraps with phosphate salts exhibit high levels of methylene blue adsorption (> 95%) probably due to mesopores development. Consequently, present results show that it is feasible to obtain high-quality ACCs by chemical activation of cellulosic-based textile scraps with acceptable yields and targeted at the removal of specific contaminants from water, through the appropriate choice of the textile waste nature used as precursor and the activating agent involved in the process for their development.