Removal of Congo red dye from aqueous environment by zinc terephthalate metal organic framework decorated on silver nanoparticles-loaded biochar: Mechanistic insights of adsorption

Abstract

In this study, zinc terephthalate-metal-organic framework decorated on the surface of poultry manure-derived biochar (ZT-MOF@Ag@C) was successfully fabricated and employed as nano-adsorbent material for Congo Red (CR)-treated aqueous solution. The physical characteristics of the developed ZT-MOF@Ag@C adsorbent were analyzed by the Brunauer–Emmett–Teller (BET) theory, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) Scanning Electron Microscopy equipped with Energy-Dispersive X-Ray Spectroscopy (SEM/EDS), and X-Ray Photoelectron Spectrometer (XPS). The characterization analysis revealed that biochar modification with ZT-MOF and AgNPs greatly enhanced the surface area. The mesopores ZT-MOF@Ag@C BET surface area of 1028 m2/g showed a maximum adsorption capacity of 416.6 mg/g. The Langmuir isotherm and pseudo-second order kinetic models best described the adsorption process of CR onto ZT-MOF@Ag@C. The thermodynamic studies revealed that the adsorption of CR on the ZT-MOF@Ag@C was spontaneous and exothermic. The as-fabricated ZT-MOF@Ag@C was observed to be stable after sixth adsorption-desorption cycles. ZT-MOF@Ag@C composite exhibited excellent potential for the treatment of CR dye from the aqueous solution. The point of zero charge, BET, XRD, XPS, SEM, and FTIR analyses confirmed that the adsorption of CR onto ZT-MOF@Ag@C nanocomposite is majorly dominated by the following mechanisms: π-π interaction, pore adsorption, electrostatic interaction, and hydrogen bonding. The biochar-derived adsorbent's performance was significantly improved through modification, thereby suggesting an effective strategy for boosting the sorbent activity.