Comparative evaluation of xerogel-based activated carbons synthesized from aliphatic aldehydes of different chain lengths

This work deals with examining the performance of xerogel-based activated carbons (XACs), which were synthesized from aliphatic aldehydes of different carbon chain lengths. These XACs were compared with those synthesized from commonly synthesized XACs. The performance of the new xerogels was determined by examining the thermo-gravimetric analysis (TGA) and Fourier transform infrared (FTIR); however, the XACs were studied using infrared spectra (IR), scanning electron microscopy (SEM), and their adsorption capacities in gas and aqueous media (nitrogen adsorption, iodine number, adsorption of phenol and methylene blue, MB). The adsorption behavior of these investigated XACs to MB was studied in detail, using the Langmuir and Freundlich adsorption equations, in addition to kinetic (Lagergren first-order and pseudo-second-order) and thermodynamic models. The results show that long -chain aldehydes have a significant effect on increasing the total pore volume (V_T). Glutaraldehyde-based carbon xerogel is recommended as an economically superior adsorbent with an S_BET x yield of 571.9 m²/g. XACs from glutaraldehyde and propionaldehyde have higher surface area than commonly synthesized ACs from formaldehyde (F), Phenol/F, Tanin/F-, Polybenzooxazine/F, and Pyrogallol/F. The best models used for MB adsorption onto XACs are Langmuir and pseudo-second-order kinetic equations. The negative values of thermodynamic parameter ΔGº and positive values of ΔHº indicate the MB adsorption process is spontaneous and endothermic.