Adsorption of Phenol from Both Acidic and Basic Industrial Waste via Newly Synthesized Metal Organic Framework Hybrid Smart Adsorbents

Abstract

Newly prepared pH-responsive metal organic frameworks (MOFs) having a specific surface area of 1400 m2/g could be exploited in the total removal of pollutants from wastewaters in this work. Smart core–shell structures of COP-150@ZIF-8 and NPC@ZIF-8 were successfully synthesized in large scales through internal extended growth under polyvinylpyrrolidone (PVP) regulation and used in phenol removal from aqueous media. The essential factors on the removal, namely pH, initial concentration of phenol, contact time, adsorbent dosage, and temperature, were studied and optimized. The experimental data were investigated by different kinetic and isotherm models, in which the removal of phenol by these smart sorbents is correlated with the Freundlich isotherm model and was found to follow the pseudo-second-order kinetic model. Excellent adsorption capacity of 1670 mg·g–1 and high efficiency were achieved in phenol removal (mixing time of only 20 min) that suggest the application of smart NPC@ZIF-8 core–shell in water filtration. Also, the optimal concentration of smart NPC@ZIF-8 and smart COP@ZIF-8 core–shell adsorbents was obtained as 300 and 250 mg·L–1, respectively. On the other hand, more than 94% removal of phenol was observed at pH = 3 for both smart nanosorbents (mere use of 0.1 g adsorbent). The results of thermodynamics confirm that the process of adsorption is exothermic and spontaneous. Moreover, having simulated the atomistic investigation of phenol removal via molecular dynamics, it was concluded that the different designed adsorbents in this work have a high capacity to remove phenol, specifically NPC@ZIF-8.