Highly efficient scavenging of Ni(II) by porous hexagonal boron nitride: Kinetics, thermodynamics and mechanism aspects

Intending to remove Ni(II) from wastewater, porous p-BN was employed to recovery Ni(II) by batch and X-ray photoelectron spectroscopy technique. The performances and mechanism of p-BN for Ni(II) sorption had been studied by diverse characterization technologies. The kinetic data was calculated to conform a pseudo-secondorder model, and isotherm data fitted to a Freundlich equation. We obtained a high removal rate and a high adsorption capacity. A possible mechanism can be expressed from XPS results. The surface of p-BN is B-OH/B-NH2 enriched and exhibits a weak alkalinity. When p-BN contact with Ni(II) solution, the hydroxide ions releases from the surface while there is a formation of BeO center dot center dot center dot Ni; the small group of BeO.Ni is acting with hydroxide ions, thereby forming BeO center dot center dot center dot Ni(OH)(2) and continuously adsorbs Ni(II) to form BeO center dot center dot center dot Ni(OH)ONi(OH) like as precipitated nucleus. Then, due to the interaction of hydroxyl-O with electron-deficient B, the veil-like Ni(OH)(2) generated from precipitated nucleus evenly attaches to p-BN. The bonding state of Ni(II) on p-BN by XPS spectra revealed that the process of adsorbing Ni(II) onto p-BN was chemisorption through the formation of Ni (OH)(2) and the interaction between hydroxyl-O and electron-deficient B. The analyses implied that p-BN is a promising candidate for recovery of Ni(II) from wastewater.