Development of bio-derived nanostructured coordination polymers based on cardanol–formaldehyde polyurethanes with ‘d5’ Mn(ii) and ‘d10’ Zn(ii) metal nodes: synthesis, characterization and adsorption behavior

Abstract

The synthesis of bio-based coordination polyurethanes (PUs) is an alternative route to conventional petro-based PUs for the green and sustainable development of coordination PUs. In the present study, we report the development of bio-based nanostructured coordination PUs with the aid of using cost effective, non-toxic, biodegradable and abundantly available renewable resource such as cardanol (Col) as a starting precursor and divalent transition metal ions Mn(II), ‘d⁵’ and Zn(II), ‘d¹⁰’ as metal centres for their potential use in the adsorption/removal of environmental pollutants, such as Congo red (CR) dye, in industrial waste water treatment. The composition and geometry of coordination PUs were confirmed by spectral techniques (FTIR and UV-visible), elemental analysis and magnetic moment. The curing behavior was investigated using ATR-FTIR technique. Thermal techniques (TGA/DTG/DTA and DSC) indicated their good thermal stability. Morphology (XRD, SEM-EDX, and HR-TEM) techniques indicated their amorphous/semi-crystalline and layered nanostructured and nanoporous patterns. The preliminary adsorption properties towards CR dye of the synthesized coordinated PUs was also investigated by a batch adsorption technique and it was found that the synthesized nanostructured and nanoporous coordination PU could be used as an effective dye adsorbent.