title: Phenolic wastewaters depuration by electrochemical oxidation process using Ti/IrO2anodes.
abstract: The electrochemical oxidation (EO) of phenolic wastewaters mimicking olive oil mill effluents was carried out in a batch stirring reactor using Ti/IrO2anodes, varying the nature (NaCl and Na2SO4) and electrolyte concentration (1.8-20 g L-1), current density (57-119 mA cm-2) and initial pH (3.4-9). Phenolic content (TPh) and chemical oxygen demand (COD) removals were monitored as a function of applied charge and over time. The nature of the electrolyte greatly affected the efficiency of the system, followed by the influence of the current density. The NaCl concentration and the initial pH influenced the process in a lesser extent. The best operating conditions achieved were 10 g L-1of NaCl, current density of 119 mA cm-2and initial pH of 3.4. These parameters led to 100 and 84.8% of TPh and COD removal, respectively. Under these conditions, some morphological differences were observed by SEM on the surface of the anode after treatment. To study the potential toxicity of the synthetic effluent in neuronal activity, this mixture was applied to rat brain slices prior to and after EO. The results indicate that although the treated effluent causes a smaller depression of the neuronal reactive oxygen species (ROS) signal than the untreated one, it leads to a potentiation instead of recovery, upon washout. Furthermore, the purification of a real olive mill wastewater (OMW), with the organic load of the synthetic effluent, using the same optimised operating conditions, achieved total phenolic compounds abatement and 62.8% of COD removal.This study demonstrates the applicability of this EO as a pre-treatment process of a real effluent, in order to achieve the legal limit values to be discharged into natural streams regarding its organic load.
authors.affiliation: Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, P3030 790, Coimbra, Portugal. sofiafajardo@eq.uc.pt.
authors.forename: Ana S
authors.initials: AS
authors.lastname: Fajardo
authors.affiliation: Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, P3030 790, Coimbra, Portugal.
authors.forename: Helga F
authors.initials: HF
authors.lastname: Seca
authors.affiliation: Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, P3030 790, Coimbra, Portugal.
authors.forename: Rui C
authors.initials: RC
authors.lastname: Martins
authors.affiliation: Department of Physics, University of Coimbra, P3004 516, Coimbra, Portugal.
authors.forename: Vanessa N
authors.initials: VN
authors.lastname: Corceiro
authors.affiliation: Department of Physics, University of Coimbra, P3004 516, Coimbra, Portugal.
authors.forename: João P
authors.initials: JP
authors.lastname: Vieira
authors.affiliation: Department of Physics, University of Coimbra, P3004 516, Coimbra, Portugal.|Centre for Neuroscience and Cell Biology, University of Coimbra, P3004 504, Coimbra, Portugal.
authors.forename: M Emília
authors.initials: ME
authors.lastname: Quinta-Ferreira
authors.affiliation: Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, P3030 790, Coimbra, Portugal.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Quinta-Ferreira
mesh_terms: D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D007495:Iridium / Q000737:chemistry*; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D012965:Sodium Chloride / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*
chemical_list: D010636:Phenols; D013431:Sulfates; D014874:Water Pollutants, Chemical; C012036:sodium sulfate; C044458:iridium oxide; D007495:Iridium; D012965:Sodium Chloride; D014025:Titanium
keywords: Electrochemical oxidation; H2DCFDA; NaCl; Neuronal toxicity; Olive mill wastewater; Phenolic acid; ROS; Ti/IrO2