Comparative Study on Adsorption of Crystal Violet and Chromium (VI) by Activated Carbon Derived from Spent Coffee Grounds

In the context of circular economy, used coffee grounds were transformed into powdered activated carbon by chemical activation using potassium hydroxide. Its characterisation was conducted in comparison with that a commercial scanning electron microscopy (SEM) coupled energy dispersive X-ray microanalysis (EDX), diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Boehm titration, and point zero charge (pHPZC) determination methylene blue number (MBN) iodine (IN). Performance prepared tested adsorption cationic dye crystal violet (CV) hexavalent chromium. Batch tests carried out effects operating parameters studied. The results collected on kinetics show followed pseudo-second order Langmuir isotherm best fits equilibrium data for thermodynamic study showed both adsorbates is spontaneous exothermic leads to decrease disorder at solid–liquid interfaces. These indicate this can be as an alternative adsorbent remove dyes heavy metals from aqueous solutions.