Enhanced adsorption performance of hierarchical S-doped Ni(OH)2 hollow nanocomposites for the removal of Congo red

In this work, nonmetallic S was doped into hierarchical Ni(OH) 2 hollow microspheres by ethanol solvothermal method using thiourea as sulfur source. Although the morphology of precursor Ni(OH) 2 is maintained, the surface states and pore properties had greatly changed after S doping. Using the as-prepared S-doped Ni(OH) 2 as adsorbents for the removal of Congo red (CR), the S-doped Ni(OH) 2 exhibited much better adsorption capacity compared with undoped Ni(OH) 2 . The adsorption behavior of both Ni(OH) 2 and S-doped Ni(OH) 2 followed the pseudo-second-order kinetic model and intraparticle diffusion model. The equilibrium data of Ni(OH) 2 could be better fitted by Langmuir model, while Freundlich model could be better used to describe the S-doped Ni(OH) 2 with a much larger adsorption capacity toward CR. The tuned microstructure and changed surface states of adsorbent after S doping may be responsible for the enhanced adsorption performance. Therefore, the doping of S species into hierarchical Ni(OH) 2 paves a new way to tune the microstructure and surface states of Ni-based materials.