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The present work investigated the degradation of a dyeing factory effluent by advanced oxidative process under UV irradiation. TiO and ZnO were used as catalysts and the influence of different concentrations of HO added to the system was studied. The catalysts were characterized in terms of crystal structure (X-ray diffraction), textural properties (Brunauer-Emmett-Teller area and pore volume) and point of zero charge, which indicated the semiconductors had a positively charged surface in an acidic medium. After 8 h of irradiation at pH 3.0 and catalyst concentration of 0.0625 g L, the effect of HO was evaluated by means of kinetic efficiency (rate constants), absorbance reduction (at 284, 621 e 669 nm), total organic carbon reduction and mineralization (in terms of the formation of ions such as [Formula: see text] and [Formula: see text]). Adding HO to the photocatalytic system significantly increased pollutants' removal, highlighting tests with 1.0 × 10 mol L, showing higher absorbance reduction and rate constants at 621 and 669 nm for TiO and best mineralization rates for ZnO. Ecotoxicity bioassays using Artemia salina L confirmed the treatment efficacy, with effluent lethal concentration (LC) increasing from 65.68% (in natura) to over 100% after photocatalysis treatment.

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ABSTRACT. The Adsorptive Cathodic Stripping Voltammetry (ACSV -differential pulse) proved to be an efficient method in the separation and quantification of two reactive textile dyes, Procion Yellow (PY) and Procion Red (PR), each containing two azo groups as chromophores and two monochlorotriazine reactive groups, at nanomolar level. for PR in B-R buffer pH 8.0, using preconcentration at -0.1 V during 60 s.Keywords: stripping voltammetry, reactive dyes, textile dyes. Determinação simultânea de corantes têxteis por Voltametria Adsortiva de Redissolução CatódicaRESUMO. A técnica de voltametria adsortiva de redissolução catódica (VARC -pulso diferencial) mostrou-se eficiente na separação e quantificação de dois corantes têxteis reativos, Amarelo Procion (PY) e Vermelho Procion (PR), cada um contendo dois grupos azo como cromóforos e dois grupos reativos monocloro-triazina, a nível nanomolar. A linearidade do método obtida para cada corante reativo foi 30,15 -633,15 nmol L -1 para AP em tampão B-R pH 8,0 e 62,56 -982,291 nmol L -1 para VP em tampão B-R pH 8,0, usando pré-concentração em -0,100 V por 60 s.

Reactive dyes, such as Procion Yellow, Procion Red, and Procion Blue, were simultaneously determined in aqueous ternary solutions using derivative cathodic stripping voltammetry following adsorption on a hanging mercury drop electrode. An electrochemical cell containing Britton-Robinson buffer solution at pH 8 was used as the supporting electrolyte. The following experimental conditions were established: À0.100 V deposition potential, 80 s deposition time, 50 mV pulse amplitude, 50 mV s À1 scan rate, and 0.40 mm 2 maximum mercury drop size. A linear response was observed over the 0.630 9 10 À3 to 1.050, 1.441 9 10 À3 to 1.572, and 0.198 to 1.570 mg l À1 ranges for Procion Yellow, Procion Red, and Procion Blue respectively. The detection limits were 0.210 9 10 À3 , 0.480 9 10 À3 , and 0.066 mg l À1 respectively, with a relative standard deviation (n = 3) of 1.22%. The accuracy of the method was evaluated by derivative spectrophotometry, certifying the results as a function of proximity. All results were similar, indicating that derivative cathodic stripping voltammetry may be efficiently applied for the simultaneous determination of textile dyes in aqueous ternary solutions.