Correction to: Statistical parameter optimization and modeling of photodegradation of methyl orange using a composite photocatalyst prepared by thermal synthesis.

The correct presentation of Table 3 is presented in this paper.

Statistical parameter optimization and modeling of photodegradation of methyl orange using a composite photocatalyst prepared by thermal synthesis.

Doping a transition metal into photocatalysts enhances the photocatalytic activity drastically. In the first part of this study, Taguchi design of experiment is applied to evaluate and optimize the efficiency of the Fe2O3/TiO2 photocatalyst synthetized by thermal method assisted by UV radiation. The contribution percentages of Fe:TiO2 mass ratio, Fe2O3/TiO2 dosage, and pH on the total organic carbon (TOC) removal are determined using analysis of variance (ANOVA). In the second part of this study, in order to model the photocatalytic degradation process, the optical properties of the photocatalyst, including the extinction, absorption, and scattering coefficients, are determined. Subsequently, the radiation transfer equation (RTE) is solved numerically based on the surface emission model using the discrete ordinate method. Furthermore, a rigorous model, including chemical reaction rates, radiation transfer, and mass transfer is proposed and validated by a set of experimental data. A satisfactory correlation between the predicted and experimental data with less than 5% error confirms the reliability of the model. The intrinsic kinetic parameters are also determined by comparing predicted values to those of the experimental results by applying non-linear regressions.

Treatment of mature landfill leachate using hybrid processes of hydrogen peroxide and adsorption in an activated carbon fixed bed column.

In this study, the treatment of mature landfill leachate is evaluated by oxidation with hydrogen peroxide (H2O2) combined with adsorption in a granular activated carbon (GAC) fixed bed column to determinate the increase in the biodegradability index, the reduction of chemical oxygen demand (COD) as well as the increase in the useful life of the GAC bed. The sample leachate from Loma de Los Cocos Landfill (Cartagena de Indias, Colombia) has a very low biodegradability ratio ranging from 0.034 to 0.048 that makes it difficult to meet the required water quality level according to the regulations. The COD removal is initially monitored in the H2O2 oxidation treatment process. The operating conditions such as pH, H2O2 dosage, and the reaction time are optimized in this process based on the percentage of COD removal. A maximum COD removal of 29.9% is achieved at an initial H2O2 concentration of 5000 mg L-1 with a pH of 8 and the reaction time of 60 min. The hybrid treatment by H2O2-GAC achieved 97.3% COD removal and 116% increase in the biodegradability ratio (from 0.072 to 0.134) while this ratio was increased by 6.5% with H2O2 alone. Moreover, the useful life of the GAC bed is increased from 45 min in the column fed with raw leachate to 170 min in the column fed with pretreated leachate and 5000 mg L-1 of H2O2 at pH of 8 that subsequently increased the activated carbon adsorption capacity. An adsorption model for leachate treated with H2O2 is also developed.

Sonophotolytic degradation of synthetic pharmaceutical wastewater: statistical experimental design and modeling.

The merits of the sonophotolysis as a combination of sonolysis (US) and photolysis (UV/H2O2) are investigated in a pilot-scale external loop airlift sonophotoreactor for the treatment of a synthetic pharmaceutical wastewater (SPWW). In the first part of this study, the multivariate experimental design is carried out using Box-Behnken design (BBD). The effluent is characterized by the total organic carbon (TOC) percent removal as a surrogate parameter. The results indicate that the response of the TOC percent removal is significantly affected by the synergistic effects of the linear term of H2O2 dosage and ultrasound power with the antagonistic effect of quadratic term of H2O2 dosage. The statistical analysis of the results indicates a satisfactory prediction of the system behavior by the developed model. In the second part of this study, a novel rigorous mathematical model for the sonophotolytic process is developed to predict the TOC percent removal as a function of time. The mathematical model is based on extensively accepted sonophotochemical reactions and the rate constants in advanced oxidation processes. A good agreement between the model predictions and experimental data indicates that the proposed model could successfully describe the sonophotolysis of the pharmaceutical wastewater.