Efficient removal of Congo red dye from aqueous solution by adsorbent films of polyvinyl alcohol/melamine-formaldehyde composite and bactericidal effects

Removal of harmful dyes and inhabitation of bacterial growth is one of the outstanding priorities in both environmental and industrial applications. The recognition of the alarming industrial discharge and insufficiency of fresh water has prompted us to develop eco-friendly and sustainable dye adsorbent films. The present investigation reports the synthesis of melamine-formaldehyde (MF) and cross-linking of polyvinyl alcohol (PVA) with MF to develop biodegradable composite films. The PVA and PVA/MF composite films were characterized by FTIR, XRD, TGA, DSC and SEM. PVA is water soluble, which has been modified with MF (13%, 23%, 33% and 43%) to increase hydrophobicity confirmed by contact angle (50 degrees to 91 degrees). The dye adsorption of Congo red (CR) has been influenced by different parameters such as contact time, pH of the solution and an effect of dye concentration were systematically investigated. The maximum adsorption capacity 221.43 mg/g of CR dye was determined by using Langmuir model from aqueous solution. The adsorption isotherm and kinetics modeling data were described by Freundlich isotherm over whole concentration range and pseudo-second rate respectively. The best antibacterial activity shown by PVA/MF composite films as compared to PVA against B. subtilis (30 mm) and S. aureus (43 mm). (C) 2020 Published by Elsevier Ltd.