Biosorption of heavy fuel oil from aqueous solution by Eichhornia crassipes (Mart.) Solms in natura.

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.

Effect of Ultrasonic Pretreatment on Melon Drying and Computational Fluid Dynamic Modelling of Thermal Profile.

Research background: Drying is one of the most traditional processes of food preservation. Optimizing the process can result in a competitive product on the market regarding its price and quality. A common method in use as a pretreatment to drying is ultrasound. The goal of this work is to analyze different drying methods with and without applying ultrasound (US) pretreatment, on heat and mass transfer, simulating numerically the temperature profile by computational fluid dynamics (CFD). Experimental approach: The melon slices were pretreated with ultrasound for 10 (US10), 20 (US20) and 30 (US30) min at 25 kHz, and the water loss and solid gain were evaluated. Samples were dried at different temperatures (50, 60 and 70 °C). The effective diffusivity was estimated, and experimental data were modelled using empirical models. The airflow in the dryer and the temperature profile in the melon slice were simulated via computational fluid dynamics (CFD). Results and conclusions: Ultrasound pretreatment reduced the drying time from 25% (samples US20 and US30 at 50 °C) to 40% (samples US20 and US30 at 70 °C). The two-term exponential model presented the best fit to the experimental data, and the diffusivity coefficients showed a tendency to increase as the time of exposure of the melon to ultrasonic waves increased. Pretreatment water loss and solid gain behaviour and drying kinetic and diffusion data were used to choose the best experimental conditions to be simulated with CFD. The heat transfer modelling through CFD showed that the temperature distribution along the melon slice was representative. Therefore, the profile obtained via CFD satisfactorily describes the drying process. Novelty and scientific contribution: The use of simulation tools in real processes allows the monitoring and improvement of existing technologies, such as food drying processes, that involve complex mechanisms, making it difficult to obtain some data. Application of CFD in the drying processes of fruits and vegetables is still very recent, being a field little explored. There is no record in the literature that uses CFD in the drying of melon.

Photodegradation applied to the treatment of phenol and derived substances catalyzed by TiO2/BiPO4 and biological toxicity analysis.

For this work, a phenol solution model was treated by an advanced oxidation process (AOPs), using the heterogeneous catalyst TiO2/BiPO4 and hydrogen peroxide combined with UVA for 240 min. An annular reactor containing a UVA lamp (80 W) was employed. A central composite rotacional design was developed employing a TiO2/BiPO4 concentration of 87 mg L-1 and a hydrogen peroxide concentration of 1800 mg L-1, being evaluated by the degradation percentage and phenol mineralization percentage as responses; 94.30 and 67.00 % were obtained for the phenol degradation and total organic carbon (TOC) conversion, respectively. The lumped kinetic model (LKM) was applied and a satisfactory profile of the residual fractions of the organic compounds present in the liquid phase as a time function with a determination coefficient (R 2 = 0.9945). The toxicity tests employing microbiological species indicated that the organisms tested for the evaluation of the toxic compounds present in the contaminated samples presented a practical low cost test, rapid execution, and high sensibility as an indicator of the presence of toxic substances in liquid effluents.

An improved method for removal of azo dye orange II from textile effluent using albumin as sorbent.

Azo dyes are generally resistant to biodegradation due to their complex structures. Acid orange II is one of the most widely used dyes in the textile industry. The influence of bovine serum albumin (BSA) in different concentrations, pH, and time of contact on Orange II was investigated using kinetics and adsorption-isotherm experiments. The results showed that the maximum colour removed from dye/albumin was 99.50% and that a stable dye-protein complex had been formed at pH 3.5 and in a proportion of 1:3 (v/v), respectively. The synthetic effluent did not show toxicity to the microcrustacean Artemia salina, and showed a CL50 equal to 97 µg/mL to azo dye orange II. Additionally, the methodology was effective in removing the maximum of orange II using BSA by adsorption at pH 3.5 which mainly attracted ions to the azo dye during the adsorption process. This suggests that this form of treatment is economical and easy to use which potentially could lead to bovine serum albumin being used as a sorbent for azo dyes.