Biodegradable sizing agents from soy protein via controlled hydrolysis and dis-entanglement for remediation of textile effluents

Edible pullulan enhanced water-soluble keratin with improved sizing performance for sustainable textile industry

Feather keratin from waste feather has become an attractive target to replace petroleum-based Poly (vinyl alcohol) sizes due to its easy film-forming ability, excellent adhesive property, biodegradability and low cost. However, poor water-solubility and brittleness of pure keratin films have become the bottlenecks and restricted the application of keratin as sizing agents. Therefore, water-soluble keratin was extracted by the reduction-preservation method and enhanced by saccharides in aqueous system to obtain all-green keratin-based slurry. The results showed that the keratin-based slurry exhibited improved sizing performance in the order of sucrose ≤ glucose ≤ pullulan by the moderate Maillard reaction. Among them, the fabricated pullulan-keratin sizes films had 27.86 %, 2684.08 % and 2911.31 % increment in tensile strength, elongation and work of facture compared with pure keratin sizes films. Besides, the addition of pullulan and subsequently moderate Maillard reaction improved the thermo-tenacity of keratin-based sizes, which was expected to tackle with the brittleness of pure keratin size films. In addition, novel pullulan-keratin sizes had good sizing performance and high desizing efficiency to cotton, cotton/polyester and polyester yarns and fabrics. Successful utilization of pullulan-keratin sizes will bring opportunities for high value utilization of waste feather and promote the green and low-carbon development of textile industry.

Application of Fenton pre-oxidation, Ca-induced coagulation, and sludge reclamation for enhanced treatment of ultra-high concentration poly(vinyl alcohol) wastewater

Poly(vinyl alcohol) (PVA) wastewater contains up to 10,000 mg/L dissolved organic carbon. A concentration of this magnitude results in a high chemical oxygen demand (COD), which generates major problems for industrial wastewater treatment in general, and the textile and chemical industries, in particular. Thus, we propose a two-stage treatment process that uses Fenton pre-oxidation, coupled with Ca-induced coagulation, to reduce the PVA and COD wastewater concentration. The optimal concentrations of FeSO₄ and CaCl₂ per gram of PVA were 0.8 g/g-PVA and 4.0 g/g-PVA, respectively, which is significantly lower than that of other reported treatments. Due to successful oxidation, the long chains of PVA molecules were broken up and the OH groups were partially oxidized to COOH. During the coagulation stage, Ca²⁺ was able to efficiently bind with the PVA pre-oxidation products, thereby forming insoluble compounds. Given initial COD and PVA concentrations of 20,450 and 10,000 mg/L, respectively, a maximum of 81.3 % COD and 96.0 % PVA was removed following this two-stage procedure. Furthermore, the sludge residue was used to remove Sb(III) from the wastewater, achieving an Sb(III) adsorption capacity of 16.0 mg/g. Thus, this study provides new insight into affordable and effective treatment of high concentration PVA-containing wastewater.