A novel study on the adsorption of low concentration Cd(II) and Ni(II) using porous boron nitride: effectiveness, coexisting anion interference, and regeneration

Abstract

Abstract The difficulty of removing low-concentration heavy metals from wastewater and the impact of coexisting anions on adsorption and regeneration performance has been widely recognized. To address this challenge, we synthesized and characterized a new adsorbent called porous boron nitride (PBN) using various techniques such as X-ray diffraction, Scanning Electron Microscopy, Fourier transform infrared spectroscopy and Brunner-Emmet-Teller measurements. We studied the adsorption kinetics and isotherms of Cd(II) and Ni(II) by PBN in the presence of interference anions using three kinetic models and four isothermal models. Our results showed that PBN reached adsorption equilibrium for Cd(II) and Ni(II) with a concentration of 10 mg/L within 5 minutes, and that the adsorption processes fit better with the pseudo-second order kinetic model and the Freundlich isothermal model. Furthermore, we found that the presence of SO42− inhibited the adsorption of Cd(II) and Ni(II), whereas SiO32−, CO32−, and PO43− promoted adsorption by forming a PBN-anion-metal ternary complex. We determined that the adsorption mechanism involved electrostatic attraction and chemisorption. After regeneration, PBN retained its crystal structure and typical pore distribution, demonstrating excellent adsorption performance for heavy metals.