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A factorial central composite orthogonal and rotatable design was employed to optimize the carbamazepine degradation using an integrated Fenton + Fenton-like oxidation process. The pH and the initial concentrations of hydrogen peroxide and ferrous and ferric ions were considered as the variables for the process optimization. A design of experiments procedure has been carried out in order to optimize the process as well as to study the interactions existing between the four variables under study. The initial concentration of hydrogen peroxide was found to be the most important variable conditioning the removal efficiency, followed by ferrous ion concentration, pH, and, finally, ferric ion concentration. The ANOVA test reported significance for 5 of the 14 involved variables. The response surface methodology technique was used to optimize carbamazepine degradation. Under optimal conditions (hydrogen peroxide concentration = 1.39 Â 10 À4 mol L À1 , ferrous ion concentration = 1.25 Â 10 À5 mol L À1 , ferric ion concentration = 1.68 Â 10 À5 mol L À1 , and pH= 3.52) total carbamazepine degradation was achieved.

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Novel adsorbents can be synthesized through tannin gelation, and they are effective agents for the removal of specific contaminants, for example the pharmaceutical species Trimethoprim. The current paper presents an optimization process for obtaining the best adsorbent from four tannin feedstock: Acacia mearnsii de Wild, Schinopsis balansae, Cupressus sempervivens, and Pinus pinaster bark extract. The cross-linking was undergone with formaldehyde and acetaldehyde, hence the type of aldehyde and its concentration in the gelation mixture were considered operative variables as well as the tannin source. The best categories resulted to be Cupressus sempervivens and Pinus pinaster with formaldehyde (3.68 mmol pure formaldehyde per g of of tannin extract) and Schinopsis balansae with diluted formaldehyde (1 mmol of pure formaldehyde per g of tannin extract). Tannin-derived rigid gels were very effective adsorbents for the removal of this dangerous pharmaceutical: trimethoprim, with maximum adsorption capacities even higher than 300 mg of trimethoprim per g of adsorbent.

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Degradation rates and removal efficiencies of different parabens, namely, methylparaben, ethylparaben, propylparaben, and butylparaben using H 2 O 2 /Fe 2þ advanced oxidation process are studied in this work. With the aim of optimizing the removal of parabens from waters through the Fenton process, a factorial central composite orthogonal and rotatable design (FCCORD) was used. H 2 O 2 and Fe 2þ ion initial concentrations were selected as independent variables. The experimental procedure planned according to the FCCORD makes it possible to optimize the removal. The occurrence of interactions between these two variables can also be analyzed with the aid of the experimental design. Fenton process provides conversion efficiencies comprising between 85 and 94 % after a reaction time of 48 h, which reveals the appropriateness of this procedure for the removal of parabens from aqueous matrices.

A wide variety of drugs have been found in wastewater treatment effluents, rivers, and lakes, including analgesics, antibiotics, and antiepileptics. Electrochemical advanced oxidation processes are promising technologies to treat low contents of toxic and biorefractory pollutants in water. Anodic oxidation of carbamazepine, the most frequently detected drug in water bodies, was carried out using boron-doped diamond (BDD) anodes at galvanostatic mode. To optimize the process and study the interaction between the four modified variables (pH, current, concentration of supporting electrolyte Na2SO4, and solution flow rate) a design-of-experiments procedure has been carried out. The influence of these four variables has been evaluated. The influence of current was the greatest in the studied variables, the second one was the salt concentration, and the third one was the flow rate. ANOVA test reported significant for 5 of the 14 involved variables and the response surface methodology technique used to optimize carbamazepine degradation. An optimum carbamazepine degradation of 100% was found at pH 9, flow rate equal to 1.25 cm3 min−1, and current density equal to 190 mA cm−2 using a supporting electrolyte concentration equal to 0.48 mol L−1.