Optimized adsorption of volatile organic compounds on the activated carbon prepared from mesquite grain: A combined experimental and computational study

In this research work, adsorption of VOC (here gasoline vapor) onto synthesized activated carbon (AC) from mesquite grain was investigated. AC was prepared using chemical activation method (with two-step, activation and paralyze) and phosphoric acid as activating agent. Also, the effect of important factors on the surface area and finally the adsorption capacity such as the phosphoric acid ratio to the raw material (RM), time and temperature of calcination were studied. Several techniques such as FT-IR, XRD, XPS, TPD, Boehm titration, BET, CHNs, SEM, and TGA/DTA, have been used to determine and confirm physicochemical surface variation during preparing and modifying the adsorbent. It was observed that activation by phosphoric acid at 600 degrees C and a 2 hr (i.e AC5:1.1-2-600) gives a surface area of 1452.4 m(2)/g. The AC5:1.1-2-600 displayed high adsorption capacity for VOC adsorption (642.86 mg.g(-1)) which was approximately 1.03-4.09 times more than other adsorbents (adsorption capacity of the AC5:1.58-2-600, AC5:1.1-2-400, AC5:0.8-2-600, AC5:1.1-2-500, AC5:1.1-1-600, and AC5:1.1-3-600 are 157.89, 240.96, 391.3, 412.5, 574.25, and 620.69 mg.g(-1), respectively). Also, AC5:1.1-2-600 desorbed 285.714 mg.g(-1)of the adsorbed VOC, which is an excellent result in desorption. Therefore, this sample was selected as the best sample. In general, all prepared adsorbents showed rapid kinetic behaviors for gasoline vapor absorption, and their maximum absorption capacity was obtained in the first 20 min. Density functional theory calculations were also carried out to give insight on the adsorption and nature of the interaction of AC with gasoline vapor. The results showed that the mean values of Eads and Delta G(ads) are negative, which confirms the reversibility of ISO absorption by AC, and is in agreement with our experimental results.

Automated summary

The synthesized activated carbon prepared using chemical activation method showed efficient adsorption capacity for gasoline vapor, with AC5:1.1-2-600 exhibiting the best performance in both adsorption and desorption.