Abstract
Petroleum comprises the monoaromatic and polycyclic aromatic hydrocarbons, which exhibit acute toxicity towards living animals. Consequently, their removal from natural environment is a priority challenge. On the other hand, biomaterials are increasingly being used as adsorbents. Pectin and chitosan are well-known polysaccharides able to form coacervate hydrogels. Aiming an increase of sorption ability by hydrophobic compounds, pectin was also functionalized with two amphiphilic compounds: β-cyclodextrin (β-CD) and poly(vinyl alcohol) (PVA). Both the modified pectin and the hydrogels were evaluated using nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The hydrogels were further characterized in terms of thermogravimetric analysis (TGA) and swelling kinetics. The interaction between the hydrogel and mix solutions containing six different aromatic compounds (BTXs and the following PAHs: pyrene, benzo(b)fluoranthene and benzo(a)pyrene) has been evaluated through sorption isotherms and kinetics. The mechanism of sorption interaction and the selectivity of the adsorbents towards different aromatic compounds were discussed. The results clearly show that the presence of β-CD and PVA into gel leads to an increase in the removal efficiency of both, BTXs and PAHs. The gels were subjected to two sorption/desorption cycles to have an assessment of the capability of adsorbents for re-use. Finally, the sorption quantification of those six aromatic compounds from a real gasoline sample onto gels has been tested.
Highlights
Polycyclic aromatic hydrocarbons (PAHs) (e.g., pyrene, benzo(b) uoranthene (B(b)F) and benzo(a)pyrene (B(a)P) and the monoaromatic hydrocarbons (MAHs) (e.g., benzene, toluene and xylene isomers (BTXs)), are carcinogenic, teratogenic and mutagenic agents in humans[1,2] and environmental priority pollutants.[3,4]These hydrocarbons are naturally present in crude petroleum and fossil fuels products, such as gasoline and diesel fuel.[5,6] BTXs constitute a signi cant percentage of petroleumIn the costal zones, PAHs and MAHs present in sewers, industrial effluents and those generated by forest res can pollute groundwater and drinking water reservoirs.[6]
The pectin functionalization was evaluated by 1H nuclear magnetic resonance (NMR) (Fig. 1)
Resonances at d 3.64, d 3.86, d 4.17 and d 5.07 ppm that can be visualized in 1H NMR spectrum of Pec-b-CD (Fig. 1A) were assigned to pectin backbone
Summary
Polycyclic aromatic hydrocarbons (PAHs) (e.g., pyrene (pyr), benzo(b) uoranthene (B(b)F) and benzo(a)pyrene (B(a)P) and the monoaromatic hydrocarbons (MAHs) (e.g., benzene, toluene and xylene isomers (BTXs)), are carcinogenic, teratogenic and mutagenic agents in humans[1,2] and environmental priority pollutants.[3,4]These hydrocarbons are naturally present in crude petroleum and fossil fuels products, such as gasoline and diesel fuel.[5,6] BTXs constitute a signi cant percentage of petroleumIn the costal zones, PAHs and MAHs present in sewers, industrial effluents and those generated by forest res can pollute groundwater and drinking water reservoirs.[6]. Polycyclic aromatic hydrocarbons (PAHs) (e.g., pyrene (pyr), benzo(b) uoranthene (B(b)F) and benzo(a)pyrene (B(a)P) and the monoaromatic hydrocarbons (MAHs) (e.g., benzene, toluene and xylene isomers (BTXs)), are carcinogenic, teratogenic and mutagenic agents in humans[1,2] and environmental priority pollutants.[3,4]. These hydrocarbons are naturally present in crude petroleum and fossil fuels products, such as gasoline and diesel fuel.[5,6] BTXs constitute a signi cant percentage of petroleum. Nowadays many materials have been used in the remediation of water contaminated with MAHs and PAHs, such as activated carbon, zeolites, microorganisms, among others.[8,9,10,11,12] these methods show some drawbacks, including the removal of trace amounts of those hydrocarbons and the cost related to pre- and post-treatments is considerable.[8]
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