<i>In situ</i> Modification of Activated Carbons by Oleic Acid under Microwave Heating to Improve Adsorptive Removal of Naphthalene in Aqueous Solutions

• Main Authors: Zhansheng Wu, Pengyun Liu, Zhilin Wu, Giancarlo Cravotto
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Processes
• Subjects: Adsorption process; Activated carbon; Oleic acid; Microwaves; Naphthalene Adsorption
• Online Access: https://www.mdpi.com/2227-9717/9/2/391

This study aimed to improve the adsorption capacity of activated carbon (AC) towards naphthalene (NAP) in aqueous solutions. Starch-based AC (SAC) and pulverized coal-based AC (PCAC) were prepared in a one-pot procedure by activation with oleic acid and KOH under microwave heating. Brunauer–Emmett–Teller (BET) specific surface areas reached 725.0 and 912.9 m²/g for in situ modified SAC (O-SAC1) and PCAC (O-PCAC1), respectively. π–π bond, H-bond, and hydrophobic effects were directly involved in the NAP adsorption process. Batch adsorption data were well fitted by pseudo-second order kinetics and the Freundlich isotherm model. As compared to ACs prepared with only KOH activation, NAP adsorption capacities of PCAC and SAC prepared by the one-pot method increased by 16.9% and 13.7%, respectively. Influences of varying factors were investigated in column adsorption of NAP using O-SAC1 and O-PCAC1. Based on breakthrough curves analysis, the larger column height (<i>H</i>), lower flow rate (<i>Q₀</i>), and lower initial concentration (<i>C₀</i>) resulted in the longer breakthrough and exhaustion times in both cases. Specifically, we concluded that O-PCAC1 exhibits better adsorption capacity than O-SAC1 in the given conditions. The optimized operating parameters were 1 cm (<i>H</i>), 1 mL/min (<i>Q₀</i>) and 30 mg/L (<i>C₀</i>). Finally, column adsorption data could be well fitted by the Thomas model.