Zinc oxide-coated coconut shell biochar-filled polylactic acid composite membranes for methylene blue removal from...

Textile dye-infused industrial effluents are toxic and recalcitrant and impart a negative environmental impact. The aim of this study is to develop and characterize a ZnO-coated coconut shell biochar-filled polylactic acid (PLA) ternary composite membrane for the effective removal of methylene blue (MB) from aqueous solutions. The coconut shell biochar was prepared by oxygen-limited pyrolysis in a muffle furnace at 500 °C and further functionalized with ZnO using the wet impregnation method. The ZnO-coated biochar was introduced into the PLA matrix at different feedings (0.25 g, 0.5 g and 0.75 g). Characterisation studies, such as field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, zeta potential measurement, water contact angle and porosity measurements were performed to confirm the successful incorporation of ZnO and to assess the changes in surface properties. The 0.5 g filled membrane, which had the highest pure water flux (PWF) (565 LMH), exhibited a maximum MB rejection of 93% at an initial concentration of 5 mg L^-1 and a flux recovery ratio of up to 79.5%. This study highlights the use of agro-waste-derived composite membranes as a potential sustainable alternative for textile dye remediation applications.