RESUMEN
This work investigated the efficiency of bioremediation of heavy fuel oil (HFO) in aqueous solutions by living Eichhornia crassipes (Mart.) Solms, also known as water hyacinth. Possibility of using post-biosorption macrophytes to produce briquettes was also studied. HFO was characterized by its density, viscosity, and Fourier-transform infrared spectroscopy. Water hyacinth was characterized by scanning electron microscope, pH of zero point of charge, buoyancy, and wettability. Experiments were performed to evaluate effects of contact time and initial oil concentration on biosorption. E. crassipes presented a hydrophobic nature, ideal for the treatment of oily effluents. Hollow structures in macrophytes were also identified, which favor capillary rise and retention of oils of high density and viscosity. Biosorption efficiency of HFO reached 94.8% in tests with initial concentration of 160 mg.L-1. A calorific value of 4022 kcal.kg-1 was obtained in briquettes made of water hyacinth post-biosorption. These results reinforce the great potential of E. crassipes as a sustainable and efficient alternative for treatment of oily effluents.
Asunto(s)
Eichhornia , Aceites Combustibles , Contaminantes Químicos del Agua , Biodegradación AmbientalRESUMEN
The synthesis of graphene oxide (GO) nanosheets, to be used as an adsorbent for the removal of textile dyes from wastewater, was optimized by the modified Hummers method. The GO nanosheets produced were compared with commercial graphene and characterized by X-ray diffractometry (XRD), Raman spectroscopy, specific surface area analysis, and zero-charge point (pHpcz). Both GO and graphene nanomaterials were originally used to adsorb two coloured dyes (direct red 81 and Indosol SFGL direct blue), which are commonly disposed in textile industrial effluents. Adsorptive assays were performed to determine and compare the variables that most influence the process, such as pH and dye concentration. The mechanisms of adsorption are proposed based on the strong interactions between the graphene oxide (due to its high functionalization with hydroxyl and carboxylic groups) and the active functional groups of the dyes (according to its colour) that, in general, overcome the weaker electrostatic forces between water/commercial graphene/dye systems.