In Situ Modification of Activated Carbons by Oleic Acid under Microwave Heating to Improve Adsorptive Removal of Naphthalene in Aqueous Solutions

Zhansheng Wu,Pengyun Liu,Giancarlo Cravotto,Zhilin Wu

doi:10.3390/pr9020391

Zhansheng Wu, Pengyun Liu + Show 2 more

Open Access

https://doi.org/10.3390/pr9020391

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Journal: Processes	Publication Date: Feb 21, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: University of Turin, Xi'an Polytechnic University

Abstract

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 (H), lower flow rate (Q0), and lower initial concentration (C0) 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 (H), 1 mL/min (Q0) and 30 mg/L (C0). Finally, column adsorption data could be well fitted by the Thomas model.

Highlights

Naphthalene (NAP), an important hydrophobic organic compound and the smallest polycyclic aromatic hydrocarbons (PAHs), is usually generated from fossil fuels [1,2].This bicyclic aromatic compound is highly toxic, extremely stable, and enriched in several environmental districts
Researchers have been committed to increasing the adsorption capacity of activated carbon (AC) by modification with different chemicals [8,9,10,11]
Two methods were compared for Starch-based AC (SAC) and pulverized coal-based AC (PCAC) modification using Oleic acid (OA) under microwave heating

Summary

Introduction

Naphthalene (NAP), an important hydrophobic organic compound and the smallest polycyclic aromatic hydrocarbons (PAHs), is usually generated from fossil fuels [1,2].This bicyclic aromatic compound is highly toxic, extremely stable, and enriched in several environmental districts (at ambient temperature the water solubility of NAP is25–31 mg/L [2]). Naphthalene (NAP), an important hydrophobic organic compound and the smallest polycyclic aromatic hydrocarbons (PAHs), is usually generated from fossil fuels [1,2]. This bicyclic aromatic compound is highly toxic, extremely stable, and enriched in several environmental districts With the increasing attention to health and environmental protection, a major effort has been made in the search for efficient and environmentally friendly methods for the removal of NAP from water. In the development of this technology, the adsorption capacity is a critical indicator for evaluating the performance of adsorbents. Researchers have been committed to increasing the adsorption capacity of ACs by modification with different chemicals [8,9,10,11]

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