Fabrication of zirconium metal-organic-framework/poly triazine-phosphanimine nanocomposite for dye adsorption from contaminated water: Isotherms and kinetics models

Abstract

Today, academia and industries are seeking some efficient adsorbents to cope with the increasing water contamination. This study aims to synthesize a hybrid material made of triazine-phosphanimine polymeric organic porous polymer (TPA-POP) and UiO-66-NH2, followed by its characterization and examination of its adsorption capacity. To this end, a central composite design (CCD) was applied to diminish the number of reaction parameters (i.e., adsorbent concentration, temperature, and initial pH) on removing the basic blue 41 (BB41). The results showed that BB41 was entirely adsorbed within 60 min by the mesoporous UiO-66-NH2/TPA-POP nanostructure. In addition, the pseudo-second-order (PSO) model was identified as the optimum formula to fit the kinetics information. This study revealed that film diffusion and adsorption are rate-limiting stages to remove the dyes. A Langmuir isotherm was applied to fit the equilibrium data, using which the highest equilibrium adsorption was calculated to be 260.7 mg/g. N2 desorption/adsorption isotherms of the UiO-66-NH2/TPA-POP and UiO-66-NH2 represent a type-I isotherm. The reduction in BET surface area from 918.7 m2 g−1 (UiO-66-NH2) to 423 m2 g−1 (hybrid material) might be explained by the hydrogen bonding between the TPA-POP and UiO-66-NH2. These interactions result in the small liquid nitrogen diffusivity into the hybrid network, thereby shrinking the BET surface area. Eventually, we recycled the adsorbent for 7 cycles to adsorb BB41 dye with no remarkable activity loss.