Moisture Harvesting Efficacy Utilizing Flower-Like ZnO Nanostructures Coated on Cotton Fabrics

Nanocomposite fabrics have been extensively employed as moisture harvesting media. In this study, flower-like zinc oxide nanostructures were coated on cotton fabrics by precipitation technique at different operational conditions of precursor concentration, temperature, and residence time. Then, the impact of aforementioned parameters on wettability of coated fabrics and morphology of nanostructures were investigated through water contact angle (WCA) measurements and SEM/EDX analyses, respectively. Optimal conditions of the coating procedure was experimentally determined and later validated using Minitab software. Afterwards, the fabrics prepared at optimal conditions were utilized in moisture harvesting experiments which were planned to scrutinize the effects of 3 parameters; humid airflow rate, temperature, and humidity on the final amount of harvested moisture. Experimental results in terms of WCA measurements led to an optimal value of 156°. Moreover, Minitab confirmation of the obtained results revealed that the optimization of coating process occurred at a precursor concentration of 3.1 mM, a temperature of 85 °C, and a residence time of 50 min. Furthermore, SEM/EDX analyses ascertain the flower-like zinc oxide nanostructure coating as well as its uniform distribution on the fabric surface. The abrasion resistance of the coated nanostructure was evaluated via performing a standard abrasion test proving the coating mechanical stability, as evidenced by a negligible reduction in the WCA. Finally, optimal moisture harvesting results led to 64.8 mg/cm².h of water, showing the dominancy of air humidity effect on the amount of harvested moisture as compared to factors such as temperature and air flowrate.