Comparison of electrochemical advanced oxidation processes for removal of ciprofloxacin from aqueous solutions

The aim of this study was to compare the efficiency of two dimensional electrochemical (2DE), electro-Fenton (EF), three dimensional electrochemical (3DE) and three dimensional electro-Fenton (3DEF) processes in removal ciprofloxacin (CIP) from aqueous solutions. The central composite design (CCD) with response surface methodology (RSM) was used to study the effect of experimental parameters on the removal efficiency of CIP by various electrochemical processes. The results showed that obtained quadratic model had a high R-squared coefficient based on the analysis of variance (ANOVA). The optimum condition for the removal of CIP by the studied processes was pH of 3, current of 0.45 A, and electrolysis time of 60 min. The results of the comparison between the processes showed that the removal efficiency of CIP after 60 min of electrolysis time is reduced as follows: 3DEF>3DE>EF>2DE. The removal efficiency enhancement was attributed to much more hydroxyl radicals generated in the three dimensional (3D) processes because single-walled carbon nanotubes (SWCNTs) could activate molecular oxygen to produce more H2O2 . These results showed that 3D systems, especially 3DEF, could be considered as an appropriate method for the treatment of persistent pollutants such as antibiotics due to good electro-catalytic activity, high efficiency, no secondary pollution

Removal of a common textile dye, navy blue (NB), from aqueous solutions by combined process of coagulation–flocculation followed by adsorption

The decolorization and removal of chemical oxygen demand (COD) of a textile dye, Navy blue CE-RN (NB), were investigated from aqueous solutions by combined process of coagulation–flocculation(C–F) and adsorption. Common coagulants (alum, lime, poly aluminum chloride (PACl), and ferric chloride) and clay montmorillonite (Mt) and nanomontmorillonite (NMt) were used in C–F and adsorption steps, respectively. The maximum COD and dye removal was observed by coagulant of PACl in the C–F process. The optimum conditions for dye removal by PACl were occurred by coagulant dose of 0.1 g/L at pH 6. In the adsorption process, the optimum contact times of 120 and 20 min were obtained for Mt and NMt, respectively. The findings indicated that the optimum conditions for the dye sorption were observed at pH 2 and the adsorbent dose 1.8 g/L. The sorption data also showed that the adsorption of NB onto the sorbents was better followed the pseudo-second order kinetic models. The dye and COD concentrations during the combined treatment process were decreased from 300 to 2–4.5 mg/L and from 732 to 2–35 mg/L, respectively. This indicates that the combined process of C–F followed by adsorption can be used as a proper alternative for the treatment of NB dye-containing wastewaters. © 2015 Balaban Desalination Publications. All rights reserved

Separation and Characterization of NOM Intermediates Along AOP Oxidation

Removal of natural organic matter (NOM) in drinking water treatment systems has been a matter of thorough study in recent years. NOM affects organoleptic properties of water and causes membrane fouling; it may act as energy source for microorganisms in distribution systems and leads to the formation of undesired disinfection by-products through its interaction with chlorine. Currently the role played by advanced oxidation processes in the removal of NOM has gained great interest; understanding the composition and behaviour of NOM throughout such a kind of processes may allow to get significant insight in order to improve efficiency. In this chapter the main techniques useful for characterization are described, and their use to investigate the changes undergone by NOM throughout several AOPs has been reviewed