Systematic optimization approach for the efficient management of the photo-Fenton treatment process (original) (raw)
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International Journal of Environmental Research and Public Health, 2021
This work addresses the dosage of H2O2 in photo-Fenton processes and the monitoring of Dissolved oxygen (DO) that can be used to drive the dosage of H2O2. The objective of this work is to show that a smarter monitoring of a process variable such as DO (for which on-line measurement can be inexpensively obtained) enables the proposal and implementation of efficient dosage strategies. The work explores the application of a recent proposed strategy consisting of: (i) initial H2O2 addition, (ii) continuous H2O2 addition until a DO set up is reached, and (iii) automatic H2O2 addition by an on-off control system based on DO slope monitoring, and applies it to the treatment of different individual contaminants and their mixtures (paracetamol and sulfamethazine). The assays performed following this dosage strategy showed improved values of TOC removed per H2O2 consumed. For the case of sulfamethazine, this improvement increased up to 25–35% with respect to the efficiency obtained without do...
Optimization of chemical processes, 2001
2.1 Classification of Models 2.2 How to Build a Model 2.3 Selecting Functions to Fit Empirical Data 2.3.1 How to Determine the Form of a Model / 2.3.2 Fitting Models by Least Squares 2.4 Factorial Experimental Designs 2 5 Degrees of Freedom 2.6 Examples of Inequality and Equality Constraints in Models References Supplementary References Problems vi Contents 3 Formulation of the Objective Function 3.1 Economic Objective Functions 3.2 The Time Value of Money in Objective Functions 3.3 Measures of Profitability References Supplementary References Problems Part I1 Optimization Theory and Methods 4 Basic Concepts of Optimization 4.1 Continuity of Functions 4.2 NLP Problem Statement 4.3 Convexity and Its Applications 4.4 Interpretation of the Objective Function in Terms of its Quadratic Approximation 4.5 Necessary and Sufficient Conditions for an Extremum of an Unconstrained Function References Supplementary References Problems
Regulation of Hydrogen Peroxide Dosage in a Heterogeneous Photo-Fenton Process
Processes
In this work, a classical linear control approach for the peroxide (H2O2) dosage in a photo-Fenton process is presented as a suitable solution for improving the efficiency in the treatment of recalcitrant organic compounds that cannot be degraded by classical wastewater treatment processes like anaerobic digestion. Experiments were carried out to degrade Lignin, Melanoidin, and Gallic acid, which are typical recalcitrant organic compounds present in some kinds of effluents such as vinasses from the Tequila and Cachaça industries. Experiments were carried in Open-Loop mode for obtaining the degradation model for the three compounds in the form of a Transfer Function, and in Closed-Loop mode for controlling the concentration of each compound. First-order Transfer Functions were obtained using the reaction curve method, and then, based on these models, the parameters of Proportional Integral controllers were calculated using the direct synthesis method. In the Closed-Loop experiments, ...
Applied Catalysis B: Environmental, 2012
A kinetics model with lumped components and TOC fractionation is proposed to track paracetamol degradation, as a model pollutant, using the photo-Fenton process. The proposed structure shows acceptable predictive capabilities regarding hydrogen peroxide consumption, TOC mineralization and dissolved oxygen evolution. The number of model parameters is considered assumable in calibrating other pollutants and degradation mixtures when applying this technology. This study covers a pollutant load range between 4 and 25 mM of TOC. The Fe 2+ initial load varied between 0.089 and 0.44 mM whilst the initial H 2 O 2 concentration tested ranged from 9 mM to 45 mM. The influence of light intensity was considered explicitly within the model whilst temperature and pH conditions were held constant. The fixed structure model, containing 9 kinetic parameters and 3 stoichiometric coefficients, was later applied to a pollutant mixture with a successful prediction of hydrogen peroxide and TOC profiles.
Experimental design for optimization of peroxide formulation stability and cost
Journal of Surfactants and Detergents, 2006
hydrogen peroxide. This active agent has the disadvantage that it becomes unstable with time, which necessitates the use of various additives in the formulation to ensure its stability. In this work, a study of the different types of surfactants, chelating agents, radical scavengers, stabilizers, and solvents, commonly used in the bleaching industry, was made to identify the mixture that better stabilizes an aqueous solution of hydrogen peroxide.
Solar Energy, 2004
Among advanced oxidation processes (AOP), the photochemically enhanced Fenton reaction (photo-Fenton) may be particularly effective for the treatment of industrial waste water, and the possibility to use solar light is an additional advantage of this process. In the present work, a Fe 3þ -exchanged zeolite Y was tested as a heterogeneous photo-Fenton catalyst for the degradation of the model organic pollutant, 2,4-xylidine. The performance of the catalyst was investigated using a bench photochemical reactor as well as solar reactors. The incident solar radiant powers (determined by ferrioxalate actinometry) showed linear correlations with the outputs of a Si-photodiode and a bolometer mounted on the solar unit, and could therefore be easily estimated from the on-line observation of the sensor outputs. The experimental design methodology was used for planning the experiments under normalized conditions and for modeling the rates of 2,4-xylidine oxidation as a function of the concentrations of the additives (Fe 3þ -exchanged zeolite catalyst and hydrogen peroxide). Although a direct quantitative comparison between both reactors is difficult (different geometries and volumes, different spectral distribution of the radiation sources), the performance of the solar reactor appears to compare favorably with that of the bench photochemical reactor.
Chemical Engineering Science, 2005
Optimization of UV/H 2 O 2 process for integration with biological waste treatment unit was done by Taguchi's orthogonal design. Four factors were considered for optimization: Dosage of H 2 O 2 , pH, circulation rate and number of doses of oxidant. For each of the four factors, experiments were run at four levels. For reduction in TOC, single dosage of hydrogen peroxide was observed to be more effective than dosing the same quantity in 2, 4 or 6 equal parts. The effect of circulation rate was found to be insignificant. If AOP were to be designed as a pretreatment step before biological oxidation, 1 mole H 2 O 2 /mole TOC is the optimum level of dosage. This level of addition increased biodegradability. If AOP were to be designed as a post-treatment step after biological oxidation, then 4 mole H 2 O 2 /mole TOC would be the optimum level of dosage. At this level, decrease in TOC was high. Higher pH of the waste liquor generally favoured reduction in TOC.
14th Mediterranean Congress of Chemical Engineering (MeCCE14) Abstracts Publication, 2020
Fenton and photo-Fenton are Advanced Oxidation processes driven by the supply of hydrogen peroxide (H 2 O 2). However, excessive hydrogen peroxide supply results in unproductive reactions and causes the process performance to decay. Thus, the goal of this work is to systematically compare different H 2 O 2 dosage strategies using a new approach based on monitoring dissolved oxygen as a performance indicator, which is assumed to directly reveal the inefficient consumption of H 2 O 2. The systematic approach proposed is a preliminary test to stablish a general methodology to define an optimal dosage scheme.