Hierarchically structured β-Ni(OH)2 clusters: a uniquely efficient aqueous phase pollutant adsorbent for multiple anionic dyes and heavy metal ions

Herein, for the first time mesostructured 3D self-assembled beta-Ni(OH)(2) clusters with high surface area, large pore size, and uniform flower-like morphology have been synthesized by implementing a novel microwave heating method, using glycine as the cappant. The beta-Ni(OH)(2) clusters are subjected to aqueous phase pollutant adsorption for multiple anionic dyes [congo red (CR), acid fuchsin (AF) and acid red 27 (AR-27)], and heavy metal ions [divalent lead ion, Pb(II) and divalent cadmium ion, Cd(II)]. The comprehensive kinetic analyses show that the adsorption of dyes and metal ions on the beta-Ni(OH)(2) cluster surface occurs by chemisorption (pseudo-second order kinetics) and intraparticle diffusion (film and pore diffusion) processes. Further, the beta-Ni(OH)(2) clusters show excellent equilibrium adsorption capacity for all the anionic dyes and metal ions. The equilibrium isotherm data show homogenous distribution of CR and AF dyes, and heterogeneous distribution of AR-27 dye on the beta-Ni(OH)(2) surface. The excellent adsorption efficiency is attributed to the microwave-induced highly hydroxylated rippled 2D surface, open pore architecture, and suitable pore distribution of the beta-Ni(OH)(2) clusters, which collectively cause strong hydrogen bonding between the cluster surface and anionic dyes as well as metal ions. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Mesostructured 3D self-assembled beta-Ni(OH)(2) clusters were synthesized for the first time with high surface area, large pore size, and uniform flower-like morphology using a novel microwave heating method. These clusters exhibited excellent adsorption capacity for various anionic dyes and heavy metal ions, with adsorption occurring through chemisorption and intraparticle diffusion processes. The superior adsorption efficiency was attributed to the unique surface characteristics and pore architecture of the beta-Ni(OH)(2) clusters.