Statistical modeling and mechanistic pathway for methylene blue dye removal by high surface area and mesoporous grass-based activated carbon using K2CO3 activator

In this study, biomass of grass waste (GW) was utilized as sustainable precursor to produce highly porous activated carbon (GWAC) with mesoporosity using a K2CO3-assisted pyrolysis approach and tested for its methylene blue (MB) dye adsorption properties. The prepared GWAC was characterized using the various techniques of specific surface area (SSA), Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), Xray diffractometer (XRD), thermogravimetric analysis (TGA), and Fourier Transform Infrared (FT-IR) spectrophotometer. The characterization results indicate the successful conversion of GW into mesoporous GWAC with high and desirable surface area of 1245.6 m(2)/g. The adsorptive performance of GWAC towards MB uptake was evaluated. To attain higher performance of the activated carbon for MB adsorption, the adsorption key parameters such as GWAC dosage (A: 0.04-0.06 g/L), pH (B: 4-10), temperature (C: 30-60 degrees C), and time (D: 5-15 min) were optimized using the Box-Behnken design (BBD) method. The adsorption equilibrium data were accurately described by the Langmuir model, where the adsorption capacity (qm; 364.2 mg/g) was recorded at the optimized process temperature of 45 degrees C. The present research also examined the mechanisms associated with the removal of MB using GWAC and observed the contribution of various MB-GWAC surface interactions (e.g., electrostatic, pi-pi, and H-bonding interactions). The present investigation shows the utility and effectiveness of GW biomass based activated carbon due to its favorable mesoporosity and cationic dye uptake in aqueous media.

Automated summary

The study successfully utilized grass waste biomass to produce highly porous activated carbon with favorable adsorption properties for methylene blue dye removal. By optimizing key parameters, the activated carbon showed highest adsorption capacity at 45 degrees Celsius, and the Langmuir model accurately described the adsorption equilibrium data.