Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej A mechanistic investigation of highly stable nano ZrO 2 decorated nitrogen-rich azacytosine tethered graphene oxide-based dendrimer for the removal of arsenite from water Subbaiah Muthu Prabhu a,b , Radheshyam Rama Pawar a , Keiko Sasaki a, ⁎ , Chang Min Park b a Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan b Department of Environmental Engineering, Kyungpook National University, 80 Daehak-ro, Daegu 41566, South Korea HIGHLIGHTS • ZrO 2 entrapped GO-based Aza-teth- ered PAMAM dendrimer composite is prepared. • Ligand exchange is likely responsible for the adsorption of AsO 3 3− . • The lamination/delamination chem- istry of GO-dendrimer composite are expressed. • Maximum adsorption capacity of 1.075 mmol/g was achieved for AsO 3 3− . • Selectivity and reusability test (4 cy- cles) did not afect the efciency of AsO 3 3− . GRAPHICAL ABSTRACT ARTICLE INFO Keywords: Dendrimer Graphene oxide Azacytosine Zirconia Arsenite Adsorption ABSTRACT We focused to synthesize graphene oxide-polyamidoamine dendrimer, up to 2nd generation, (GO-gen2) via a grafting method and the tethered groups were further covalently functionalized with a nitrogen-rich of an aromatic triazine ring of 5-azacytosine (Aza). Zirconia nanoparticles (ZrO 2 ) has been identifed as promising material for removal of AsO 3 3− from water, however, its practical applicability is hindered due to its nanosize. Hence, ZrO 2 was successfully decorated through biomolecule assist on GO-gen2-Aza dendrimer. Various amounts of GO-gen2-Aza were used as stable supports to develop the nanocomposites with ZrO 2 . Then, the adsorption efciency of highly toxic AsO 3 3− on developed composites was investigated for water treatment. The synthesized GO-dendrimer composites were char- acterized well before and after adsorption of AsO 3 3− using FTIR, PXRD, SEM, XPS, TGA, TEM and BET analysis. Particle size distribution of ZrO 2 revealed the peak top at 28 nm by zeta potential measurement. During synthesis, the GO sheets of composite were laminated by incorporation of ZrO 2 nanoparticles. The results of the batch experiments showed that ZrO 2 @2%GO-gen2-Aza dendrimer had higher adsorption density of AsO 3 3− than that of other devel- oped forms of dendrimer composites. Langmuir equation well described the adsorption isotherm with the maximum adsorption capacity of 1.075 mmol/g. In addition, the enhanced AsO 3 3− adsorption density on ZrO 2 surface of ZrO 2 @x%GO-gen2-Aza, in which the GO-sheets were delaminated, resulting more ZrO 2 was dispersed homo- geneously in the GO-sheets for maximum uptake of AsO 3 3− from water, confrmed by PXRD patterns. These results suggested that the developed GO-based dendrimer materials can be utilised for the practical remediation of toxic AsO 3 3− and other similar types of toxic ions, selenite, phosphate and fuoride from the contaminated water. https://doi.org/10.1016/j.cej.2019.03.277 Received 26 December 2018; Received in revised form 15 March 2019; Accepted 29 March 2019 ⁎ Corresponding author. E-mail addresses: muthuprabhu@mine.kyushu-u.ac.jp (S.M. Prabhu), keikos@mine.kyushu-u.ac.jp (K. Sasaki). Chemical Engineering Journal 370 (2019) 1474–1484 Available online 29 March 2019 1385-8947/ © 2019 Elsevier B.V. All rights reserved. T