Synthesis, characterisation and multi cationic dyes adsorption by surface modified bagasse nanocellulose incorporated porous polyurethane composites: adsorption performance, desorption and seed germination investigations

In this work, modified bagasse nanocellulose reinforced porous polyurethane (PU) composites with a mix of polyol components (PEG 6000), methyl di-isocyanate (MDI) and seed oil based polyol (chaulmoogra and grape) were prepared. MDI serves as the soft segment while PEG 6000 serves as the hard segment in the PU system. Here, the reinforcer is modified nanocellulose, while the catalyst used is DABCO. The prepared PU composites samples were characterised using XRD, SEM, FTIR, TGA, and FE-SEM. The nanocellulose and modified nanocellulose samples' crystallinity indices as indicated by XRD shows slightly decreased crystallinity index for modified nanocellulose. The SEM findings demonstrate that the modified nanocellulose filled polyurethane composites (mNC-PU) became more brittle as the mNC content increased. The obtained porous PU composite is used as an adsorbent to study the removal effectiveness of cationic dyes (rhodamine 6G and methylene blue) individually and in mixed form. The results showed that varying nanocellulose concentration affects the synthesis and flexibility of the composites prepared. Thermogravimetric analysis of the PU and CNC reinforced PU indicates improved thermal stability for the composites. Adsorption efficiency is found to be affected by several parameters including filler quantity, adsorbent dosage, pH, temperature, and duration. The outcome suggests that the modified bagasse nanocellulose reinforced porous polyurethane could be used as a low cost adsorbent for the removal of cationic dyes from wastewater when binary mixture is present in the effluent. Desorption studies suggest that these materials can be reused.