Development of Novel Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ Magnetic Nanoparticles with Outstanding VOC Removal Capacity: Characterization, Optimization, Reusability, Kinetics, and Equilibrium Studies Mehmet S ̧ akir Ece, Sinan Kutluay,* O ̈ mer S ̧ ahin, and Sabit Horoz Cite This: https://dx.doi.org/10.1021/acs.iecr.0c03883 Read Online ACCESS Metrics & More Article Recommendations * sı Supporting Information ABSTRACT: The adsorption of pollutants to the surface of adsorbents plays a critical role in the effectiveness of adsorption technology for air purification applications. Herein, novel magnetic nanoparticles functionalized with 1,4- diaminoanthraquinone (1,4-DAAQ), namely, Fe 3 O 4 /activated carbon (AC)@SiO 2 @ 1,4-DAAQ, were innovatively synthesized via co-precipitation and sol-gel techniques. After that, these nanoparticles were used for high-efficiency removal of volatile organic compounds (VOCs) (i.e., benzene and toluene). The synthesized nanoparticles were characterized by various techniques such as Fourier transform IR spectroscopy, thermogravimetric analysis/differential thermal analysis, scanning electron micros- copy, and Brunauer-Emmett-Teller analysis. The dynamic adsorption process of VOCs was optimized based on operating parameters. The adsorption experiments revealed that Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ showed exceptional performance for the removal of VOCs. It was observed that for benzene, Fe 3 O 4 , AC, Fe 3 O 4 /AC, Fe 3 O 4 / AC@SiO 2 , and Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ exhibited dynamic adsorption capacities of 180.25, 228.87, 295.84, 382.10, and 1232.77 mg/g, respectively. Additionally, for toluene, they exhibited dynamic adsorption capacities of 191.08, 274.53, 310.26, 421.30, and 1352.16 mg/g, respectively. This indicated that the modification of 1,4- DAAQ could greatly enhance the dynamic adsorption capacity of Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ for VOCs. In addition to the apparent adsorptive behavior in removing VOCs, Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ exhibited high repeatability. After ten consecutive adsorption/desorption cycles, for benzene and toluene, Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ retained 79.36 and 78.24% of its initial adsorption capacity, respectively. According to the characterization results, the average pore diameter for Fe 3 O 4 /AC@SiO 2 @1,4- DAAQ was determined to be 24.46 nm, indicating that they were in the mesopore range. The adsorption mechanism of the VOCs on Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ was clarified by investigating the isotherm and kinetic criteria in detail. Isotherm models suggested that the adsorption process of VOCs is physical. Moreover, from the analysis of diffusion-based rate-limiting kinetic models, the findings reveal a combination of intraparticle diffusion as well as film diffusion throughout the adsorption process of VOCs. In addition, it was concluded from the analysis of the mass transfer model factors that global mass transfer and internal diffusion are more effective than film diffusion. The results demonstrated that the Fe 3 O 4 /AC@SiO 2 @1,4-DAAQ nanoadsorbent is a promising material for the effective removal of VOCs. 1. INTRODUCTION Volatile organic compounds (VOCs) are a group of easily evaporated carbon-based chemicals with a saturated vapor pressure of more than 133.3 Pa at room temperature and a boiling point ranging from 50 to 260 °C. VOCs discharged into the atmosphere easily react with various substances in the atmosphere because of their high reactivity. They participate in photochemical reactions with nitrogen oxides under sunlight and become pioneers of ozone and secondary organic aerosols. Ultimately, they cause the stratospheric ozone layer to become thinner. Industrial activities such as coal-fired power plants, drug production, transportation, packaging, printing, and furniture decoration are among the main sources of VOC emissions. The emissions of VOCs have increased significantly because of expanding urbanization and developing industrial- ization. Because of the serious environmental hazards they cause, interest in the removal of VOCs has increased in recent years. Also, most VOCs are toxic and pose serious threats to human health. 1,2 The removal of harmful VOCs is important Received: August 6, 2020 Revised: November 1, 2020 Accepted: November 3, 2020 Article pubs.acs.org/IECR © XXXX American Chemical Society A https://dx.doi.org/10.1021/acs.iecr.0c03883 Ind. Eng. Chem. Res. XXXX, XXX, XXX-XXX Downloaded via UNIV OF NEW ENGLAND on November 29, 2020 at 13:03:28 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.