Kinetics & dynamic studies of dye adsorption by porous graphene nano-adsorbent for facile toxic wastewater remediation

Abstract

Due to high surface area, large delocalized pi (π) electrons, and tunable chemical attributes, porous graphene Nanomaterials (PGN) are exceptionally fascinating adsorbents for environmental decontamination applications. A facile wet-chemical exfoliation is used to synthesize exfoliated Graphene, leading to low-temperature treated porous reactive graphene Nano-adsorbents (APG), observing dye adsorption and removal of dissolved toxic contents. Various systematic characterization techniques are employed to investigate and correlate the physical and chemical moieties between APG and its counterpart Graphene oxide (GO), resorting to the structural properties, optimized surface functionality, adsorption characteristics, and mechanisms. The distinctive average crystal size of 4.49 Å for APG is observed compared to GO (5.7 nm) and Graphite (71 nm). A large specific surface area (SSA) of APG is estimated as 589.06 m2g−1 with a “slit-like” porous structure and induced surface roughness, distinct from observed materials (graphite 3.91m2g−1 and GO 84.05 m2g−1). Results demonstrate that methyl blue (MB) adsorptive removal capacity (821.05 mgg−1) reaches 99.69% within 120 min, and adsorption follows the Langmuir isotherm and pseudo-2nd-order kinetic models. Interestingly, as-synthesized adsorbent accommodates substantial demineralization by reducing chemical oxygen demand (COD) over 98% with total dissolved solids (TDS), remaining well below the permissible limit. Above all, results advocate that APG can be identified as a promising low-cost adsorbent.