-The solar driven photo-Fenton process for treating water containing phenol as a contaminant has been evaluated by means of pilot-scale experiments with a parabolic trough solar reactor (PTR). The effects of Fe(II) (0.04-1.0 mmol L -1 ), H 2 O 2 (7-270 mmol L -1 ), initial phenol concentration (100 and 500 mg C L -1 ), solar radiation, and operation mode (batch and fed-batch) on the process efficiency were investigated. More than 90% of the dissolved organic carbon (DOC) was removed within 3 hours of irradiation or less, a performance equivalent to that of artificially-irradiated reactors, indicating that solar light can be used either as an effective complementary or as an alternative source of photons for the photo-Fenton degradation process. A non-linear multivariable model based on a neural network was fit to the experimental results of batch-mode experiments in order to evaluate the relative importance of the process variables considered on the DOC removal over the reaction time. This included solar radiation, which is not a controlled variable. The observed behavior of the system in batch-mode was compared with fed-batch experiments carried out under similar conditions. The main contribution of the study consists of the results from experiments under different conditions and the discussion of the system behavior. Both constitute important information for the design and scale-up of solar radiation-based photodegradation processes.
Solar reactors can be attractive in photodegradation processes due to lower electrical energy demand. The performance of a solar reactor for two flow configurations, i.e., plug flow and mixed flow, is compared based on experimental results with a pilot‐scale solar reactor. Aqueous solutions of phenol were used as a model for industrial wastewater containing organic contaminants. Batch experiments were carried out under clear sky, resulting in removal rates in the range of 96–100 %. The dissolved organic carbon removal rate was simulated by an empirical model based on neural networks, which was adjusted to the experimental data, resulting in a correlation coefficient of 0.9856. This approach enabled to estimate effects of process variables which could not be evaluated from the experiments. Simulations with different reactor configurations indicated relevant aspects for the design of solar reactors.
Soluble bio-organic substances (SBO) obtained from urban bio-wastes have been investigated as chemical auxiliaries in photochemical processes. For this purpose, photodegradation of the antibiotic sulfadiazine (SDZ) (25 mg L-1) was studied under simulated sunlight. Experiments were performed to check the role of the SBO as additives for the photo-Fenton process ([SBO] 0 = 20 mg L-1 , [H 2 O 2 ] 0 = 244 mg L-1 , [Fe 3+ ] 0 = 5 mg L-1) at pH 3, 5.2 and 7. The results show that in slightly acidic conditions (pH = 5.2) the SBO improve the photo-Fenton process. Organic compounds present in the SBO are able to complex iron cations and hence, iron precipitation could be avoided. Finally, the results of a Doehlert uniform array design were used to fit a neural network model, which was found to be an effective, simple approach to successfully modeling the photo-Fenton degradation using SBO within the range of experimental conditions. This model might be useful in process optimization.
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