Abstract
Volatile organic compounds (VOCs), which emerge as multicomponent pollutants through many industrial processes, pose a serious threat to human health and the eco-environment due to their volatility, toxicity and dispersion. Hence, the study of competitive adsorption of multicomponent VOCs is of practical and scientific importance. Herein, the perlite-supported Fe3O4@SiO2@8-hydroxyquinoline-5-sulfonic acid (perlite-Fe3O4@SiO2@8-HQ-5-SA) was designed as a novel magnetic nanoadsorbent by a simple strategy and employed for the competitive adsorption of multicomponent toluene, ethylbenzene and xylene in the vapor-phase targeted as VOCs. The successfully prepared perlite-Fe3O4@SiO2@8-HQ-5-SA was characterized by means of SEM, EDX, FT-IR, VSM and BET analyses. Adsorption capacities of 558 mg/g, 680 mg/g and 716 mg/g were achieved for single component toluene, ethylbenzene and xylene, respectively. It was concluded that the adsorption capacities for both binary and ternary components were significantly decreased compared to single component adsorption. The competitive adsorption capacity order of the binary and ternary component VOCs was xylene > ethylbenzene > toluene due to their competitive dominance. The rate-limiting kinetic analysis indicated that the adsorption rates were determined by both the film diffusion and intraparticle diffusion. The analysis of the error metrics demonstrated that the three-parameter isotherm models better described the adsorption data compared to the two-parameter models. In particular, the Toth model provided the closest fit to the experimental equilibrium data. The thermodynamic analysis indicated the spontaneous nature and probability (ΔG° <0), exothermic (ΔH° <0), physical (ΔH° <20 kJ/mol) and a declination in the degree of randomness (ΔS° <0) of the adsorption processes. The reuse efficiency of perlite-Fe3O4@SiO2@8-HQ-5-SA for toluene, ethylbenzene and xylene decreased to only by 88.91%, 88.07% and 87.16% after five recycles. The perlite-Fe3O4@SiO2@8-HQ-5-SA has a significant adsorptive potential compared to other adsorbents reported in the literature, thus it could be recommended as a promising nanoadsorbent for VOCs in industrial processes.
| Original language | English |
|---|---|
| Article number | 139636 |
| Journal | Chemosphere |
| Volume | 338 |
| DOIs | |
| Publication status | Published - Oct 2023 |
Bibliographical note
Publisher Copyright:© 2023 Elsevier Ltd
Funding
This work was supported by Siirt University Scientific Research Projects Coordination Unit under Project Number 2021-SİÜFEB-054 . Volatile organic compounds (VOCs), which emerge as multicomponent pollutants through many industrial processes, pose a serious threat to human health and the eco-environment due to their volatility, toxicity and dispersion. Hence, the study of competitive adsorption of multicomponent VOCs is of practical and scientific importance. Herein, the perlite-supported Fe3O4@SiO2@8-hydroxyquinoline-5-sulfonic acid (perlite-Fe3O4@SiO2@8-HQ-5-SA) was designed as a novel magnetic nanoadsorbent by a simple strategy and employed for the competitive adsorption of multicomponent toluene, ethylbenzene and xylene in the vapor-phase targeted as VOCs. The successfully prepared perlite-Fe3O4@SiO2@8-HQ-5-SA was characterized by means of SEM, EDX, FT-IR, VSM and BET analyses. Adsorption capacities of 558 mg/g, 680 mg/g and 716 mg/g were achieved for single component toluene, ethylbenzene and xylene, respectively. It was concluded that the adsorption capacities for both binary and ternary components were significantly decreased compared to single component adsorption. The competitive adsorption capacity order of the binary and ternary component VOCs was xylene > ethylbenzene > toluene due to their competitive dominance. The rate-limiting kinetic analysis indicated that the adsorption rates were determined by both the film diffusion and intraparticle diffusion. The analysis of the error metrics demonstrated that the three-parameter isotherm models better described the adsorption data compared to the two-parameter models. In particular, the Toth model provided the closest fit to the experimental equilibrium data. The thermodynamic analysis indicated the spontaneous nature and probability (ΔG° <0), exothermic (ΔH° <0), physical (ΔH° <20 kJ/mol) and a declination in the degree of randomness (ΔS° <0) of the adsorption processes. The reuse efficiency of perlite-Fe3O4@SiO2@8-HQ-5-SA for toluene, ethylbenzene and xylene decreased to only by 88.91%, 88.07% and 87.16% after five recycles. The perlite-Fe3O4@SiO2@8-HQ-5-SA has a significant adsorptive potential compared to other adsorbents reported in the literature, thus it could be recommended as a promising nanoadsorbent for VOCs in industrial processes.Various materials such as zeolite-based, carbon-based, organic polymers, composites and magnetic nanoparticles (MNPs) have been developed and applied for VOC adsorption in terms of adsorption capacity, stability and regenerability (Zhu et al., 2020b; Kutluay, 2021; Ece and Kutluay, 2022). Among the tested adsorbents, functionalized Fe3O4 MNPs have been more attractive due to their chemical functionality, high average pore diameter providing a large number of active sites, surface area, selectivity, affinity and capacity (de las Nieves Piña et al., 2018). The main focus of the literature has been on the development and functionalization of Fe3O4 MNPs that can be specifically designed for selectivity to interact with the desired component (Al-Anazi, 2022). Non-functionalized Fe3O4 MNPs are unstable in air or moisture, easily oxidised and easily agglomerated due to their high surface energy. To overcome these obstacles, studies have been carried out to coat their surfaces with organic, inorganic or doped hybrid polymers. These strategies include the coating/functionalizing Fe3O4 MNPs with suitable surfactants, carbon, silica (SiO2), organic compounds (Lu et al., 2007). So far, many preparation methods have been developed for MNPs and their multifunctional composites, such as chemical co-precipitation, sol-gel synthesis, thermal separation or reduction, microemulsion polymerization, and hydrothermal synthesis. Fe3O4 can be modified with SiO2 using organosilanes (as the silica source). The sol-gel (Stöber) method is the most commonly used method to coat the surface of Fe3O4 MNPs with SiO2. SiO2 coated on the surface of Fe3O4 reduces the zero isoelectric point and magnetic dipole interaction of the particles and provides a homogeneous distribution. Thus, it prevents both the oxidation of Fe3O4 and the agglomeration of Fe3O4 MNPs (Zhang et al., 2016). In recent years, researchers have found that MNPs require precise control of production conditions and surface functionalization, as the final surface properties determine their physicochemical properties, colloidal stability, biological behaviour and magnetism. Although nanomaterials have been successful in chemical, biological, biomedical and material applications, their environmental applications have started very recently (Zhou et al., 2016). On the other hand, the development of MNPs supported by high surface area materials is a very important strategy to provide high adsorption capacity for pollutant removal. Despite the disadvantages of other surface modifiers (activated carbon, graphene oxide, zeolite, etc.), perlite has significant advantages for the development of efficient materials. The preparation process of perlite-supported materials is simple. Perlite, an industrial and vitreous volcanic mineral, is environmentally friendly because it is natural. It has low density and thermal conductivity, high SiO2 content (more than 70%), silanol atoms give it adsorptive character (Acemioğlu, 2005). Perlite, an aluminosilicate, is an inexpensive mineral with an amorphous structure that is abundant. Low cost, non-toxicity, fire resistance, higher surface area, rich content (water, Al2O3 and SiO2 as well as K2O, Na2O, CaO, MgO, TiO2, MnO2, SO3), chemical inertness and lightness are some of the distinguishing features of perlite. Perlite-based composites have high mechanical and thermal stability (Jafarirad et al., 2021). However, it offers an attractive and cost-effective option for adsorption applications as it can be easily functionalized (Nethaji et al., 2013). SiO2 functionalizes the surface of Fe3O4 MNPs, increasing their chemical stability and providing better protection against toxicity. It is a very good surface modifier due to its ability to easily conjugate with various functional groups. An advantage of the SiO2 coating is that, thanks to its hydroxyl groups, it can be chemically modified with organic compounds containing functional groups such as amine and carboxylate (Laurent et al., 2008). 8-Hydroxyquinoline-5-sulfonic acid (8-HQ-5-SA) and its derivatives are as unique in analytical chemistry as EDTA and its analogues (Soroka et al., 1987). Applied for material modification and one of the most important chelators for metal ions, 8-HQ-5-SA is widely used in a wide variety of analytical techniques and in the construction of highly sensitive fluorescent sensors (Badiei et al., 2011). Functionalization of perlite-supported Fe3O4@SiO2 MNPs with functional groups, such as 8-HQ-5-SA, provides new active sites for high adsorption capacity (de las Nieves Piña et al., 2018).To the best of our knowledge, the designing perlite-supported Fe3O4@SiO2@8-HQ-5-SA (perlite-Fe3O4@SiO2@8-HQ-5-SA) as a promising magnetic nanoadsorbent for the competitive adsorption of multicomponent VOCs has not been reported in the literature. With this motivation, novel perlite-Fe3O4@SiO2@8-HQ-5-SA was designed and employed for the competitive adsorption of multicomponent toluene, ethylbenzene and xylene in the vapor-phase. The successfully prepared perlite-Fe3O4@SiO2@8-HQ-5-SA was characterized by means of SEM, EDX, FT-IR, VSM and BET analyses. In addition, kinetics, isotherm, thermodynamic and reusability studies were performed.The comparison of the adsorption capacities of Fe3O4, perlite-Fe3O4, perlite-Fe3O4@SiO2 and perlite-Fe3O4@SiO2@8-HQ-5-SA for toluene, ethylbenzene and xylene is presented in Fig. 6a. The results showed that supporting Fe3O4 with perlite, coating with SiO2 and functionalization with 8-HQ-5-SA was a highly effective strategy to significantly enhance the adsorption capacity. It has been reported in the literature that the adsorption capacity due to van der Waals force generally increases in direct proportion to the increase in surface area (Kutluay, 2021). Although the surface area of perlite-Fe3O4@SiO2@8-HQ-5-SA was not very high compared to the tested nanoadsorbents, its adsorption capacity was found to be quite high. A possible explanation for this situation is that due to the presence of -NH2 and SO3H functional groups in the chemical structure of perlite-Fe3O4@SiO2@8-HQ-5-SA, interactions such as p-p bonds, electrostatic interactions and hydrogen bonds in the adsorption mechanism cause an increase in adsorption capacity (Vellingiri et al., 2017; Dashtian et al., 2018). Considering that perlite-Fe3O4@SiO2@8-HQ-5-SA has the best adsorption capacity among the tested nanoadsorbents, competitive adsorption, kinetic, isotherm, thermodynamic and reproducibility studies were performed with perlite-Fe3O4@[email protected] work was supported by Siirt University Scientific Research Projects Coordination Unit under Project Number 2021-SİÜFEB-054.
| Funders | Funder number |
|---|---|
| EDTA | |
| Siirt University | 2021-SİÜFEB-054 |
| VOCs | Al2O3, SiO2 |
Keywords
- Competitive adsorption
- Kinetics/isotherms
- Magnetic nanoadsorbent
- Multicomponent VOCs
- Reusability
