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Sustainable fabrication of protective cotton, using bio-extracts, is becoming increasingly attractive. However, many shortcomings—including the introduction of potentially hazardous mordants or modifiers to cotton, annoying colour changes after finishing, and low processing efficiency—require further melioration. Therefore, an efficient ultrasonic-assisted colourless finishing process was developed in this study, to fabricate ultraviolet-proof and antimicrobial cotton. A pair of oppositely charged bio-based substances, i.e., tannin acid (TA) and hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were introduced during the ultrasonic process. The results reveal that cationic HACC significantly promotes the adsorption of TA to cotton. The apparent colour of the cotton remained almost unchanged after finishing. Based on Pesudo first-/second-order kinetic models, chemisorption was verified as the dominant mechanism. Efficiency under ultrasound was enhanced by 5.3% (70 °C) and 27% (90 °C), respectively. A mathematical modelling study established the factors to be in the following order of significance: concentration > pH > temperature. Under optimal conditions, a theoretical maximum UPF of 380.8 was achieved. TA (8 g/L)-treated cotton deactivated up to 98% of Escherichia coli, and also provided excellent UV-shielding performance. In general, the ultrasonic-assisted eco-dyeing and finishing process for cotton was explored in depth from practical and theoretical perspectives, which should push forward the development of the sustainable textile industry. [ABSTRACT FROM AUTHOR]

The paper describes hydrometallurgical methods to recycle wastes of vanadium pentoxide chemical fabrication. Sludges containing a significant amount of V2O5 can be considered as an additional source of raw materials for vanadium production. We studied the one-stage leaching method using various iron-based reductants for converting V5+ to V4+ in a solution allowing to precipitate V when its concentration in the solution is low. As a result of the reduction leaching with further precipitation, we obtained concentrates with V2O5 content of 22–26% and a high amount of harmful impurities. Multistage counterflow leaching can be used to fabricate solutions with vanadium pentoxide concentration suitable for vanadium precipitation by hydrolysis and adding ammonium salts. The solutions with V2O5 content of ≈15 g/L can be obtained from the initial sludge by three-stage counterflow vanadium leaching. A concentrate with a content of 78 wt% V2O5 can be precipitated from these solutions at pH = 2.4 by adding ammonium chloride. Additionally, concentrate with V2O5 content of ≈94 wt% was precipitated from the solution with a concentration of >20 g/L V2O5 obtained from the roasted sludge. The concentrates were purified for increasing the vanadium content to 5–7%. The consumption and technological parameters of the considered processes are presented in the paper. [ABSTRACT FROM AUTHOR]