Eco-friendly and cost-effective synthesis of ZnO nanopowders by Tapioca-assisted sol-gel route

Abstract This study presents a low-cost method for obtaining nanometric zinc oxide (ZnO) using a cassava starch (Tapioca)-assisted by sol-gel route. In this procedure, ZnO nanopowders (~20 nm and 59 nm according to XRD) were obtained after 2 h of calcination at 500oC. The cassava starch played a fundamental role during the sol-gel synthesis allowing the obtention of ZnO nanopowders (ZnOT) with crystallite size three times smaller than the ones without cassava starch (ZnO). SEM and TEM images corroborate the idea that Tapioca inhibited crystal growth in ZnOT when compared to the ZnO obtained from the same methodology. The synthesis of the obtained ZnOT was studied by FTIR and the results point to a possible interaction between zinc cations and C–O groups of glucose molecule that arises from the starch hydrolysis; thus, showing that Tapioca works as a good chelating agent, as well as presenting a very low cost.