Abstract
Nickel oxide (NiO) nanoflowers are synthesized via a one-pot method using an amphiphilic block copolymer in aqueous solution. Pluronics F-127 block copolymer works as a structure-directing agent in the formation of the NiO nanoflowers. The controlled hydrolysis of the precipitating agent slowly releases ammonia that can form Ni(OH)(2), which is stabilized in the polymer solution. The calcination removes the polymeric part of the nanocomposite and converts Ni(OH)(2) into NiO with a face-centered cubic (FCC) phase. The synthesized NiO nanoflowers possess a mesoporous structure with an average surface area of 154 m(2)/g. Physisorption and electrostatic interactions between negatively charged congo red (CR) and positively charged NiO nanoflowers allow the adsorption of CR dye at ambient conditions. The adsorption of dyes follows pseudo-second-order kinetics, and the adsorbents are regenerated by calcination and recycled three times at similar efficiencies. Published by Elsevier B.V.