Eduardo Lins de Barros Neto

Oil removal from produced water by conjugation of flotation and photo-Fenton processes

The present work investigates the conjugation of flotation and photo-Fenton techniques on oil removal performance from oilfield produced water. The experiments were conducted in a column flotation and annular lamp reactor for induced air flotation and photodegradation steps, respectively. A nonionic surfactant was used as a flotation agent. The flotation experimental data were analyzed in terms of a first-order kinetic rate model. Two experimental designs were employed to evaluate the oil removal efficiency: fractional experimental design and central composite rotational design (CCRD). Overall oil removal of 99% was reached in the optimum experimental condition after 10 min of flotation followed by 45 min of photo-Fenton. The results of the conjugation of induced air flotation and photo-Fenton processes allowed meeting the wastewater limits established by the legislations for disposal.

Integration of processes induced air flotation and photo-Fenton for treatment of residual waters contaminated with xylene.

Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min(-1) for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H(2)O(2) concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal.

Photodegradation of non-ionic surfactant with different ethoxy groups in aqueous effluents by the photo-Fenton process

The photo-Fenton process was applied to degrade non-ionic surfactants with different numbers of ethoxy groups, seven (E7), ten (E10) and twenty-three (E23). The effects of H2O2 concentration, Fe(II) concentration and number of ethoxy groups on the mineralization of surfactants were investigated. The response surface methodology (RSM) was applied to determine optimal concentrations of Fentons reagents for each surfactant. The efficiency of the photo-Fenton process reached 95% for all surfactants studied at 45 min in optimal conditions determined in this work. The analysis of results showed that the efficiency depends upon the number of ethoxy groups in the surfactant. The increase in ethoxy groups favoured the mineralization of surfactants. The analysis of variance (ANOVA) was applied, and according to the F-test the models for the mineralization of surfactants were considered significant and predictable. The photo-Fenton process has proven to be feasible for the degradation of ethoxylated surfactants in aqueous solution.

Determinación de los Parámetros del Modelo de Flory- Huggins para estimación del Punto de Nube de Surfactantes No Iónicos

The cloud point of different polyethoxylated surfactants have been experimentally determined and thermodynamic parameters such as enthalpy and entropy of mixing using the Flory-Huggins model have been determined. The non-ionic surfactants are compounds that can be used as separation aid in processes such as extraction. This separation process is based on a chemical phenomenon that occurs when a solution of non-ionic surfactants is subjected to warming, increasing the temperature until getting a turbid liquid. The temperature at this point is known as the cloud point. The experimental methodology considered the preparation of solutions of 0.25 to 20% by mass for each surfactant studied and the heating process until reaching the cloud point. The parameters in the Flory-Huggins model were obtained using the Levenberg-Marquardt method and presented a satisfactory adjustment to the experimental data for all the surfactants studied in this work.