RESUMEN
The objective of this study was to investigate several operating parameters, such as open circuit, different external resistance, pH, supporting electrolyte, and presence of aeration that might enhance the degradation rate as well as electricity generation of batik wastewater in solar photocatalytic fuel cell (PFC). The optimum degradation of batik wastewater was at pH 9 with external resistor 250 Ω. It was observed that open circuit of PFC showed only 17.2 ± 7.5% of removal efficiency, meanwhile the degradation rate of batik wastewater was enhanced to 31.9 ± 15.0% for closed circuit with external resistor 250 Ω. The decolorization of batik wastewater in the absence of photocatalyst due to the absorption of light irradiation by dye molecules and this process was known as photolysis. The degradation of batik wastewater increased as the external resistor value decreased. In addition, the degradation rate of batik wastewater also increased at pH 9 which was 74.4 ± 34.9% and at pH 3, its degradation rate was reduced to 19.4 ± 8.7%. The presence of aeration and sodium chloride as supporting electrolyte in batik wastewater also affected its degradation and electricity generation. The maximum absorbance of wavelength (λmax) of batik wastewater at 535 nm and chemical oxygen demand gradually decreased as increased in irradiation time; however, batik wastewater required prolonged irradiation time to fully degrade and mineralize in PFC system.
Asunto(s)
Fuentes de Energía Bioeléctrica , Eliminación de Residuos Líquidos/métodos , Análisis de la Demanda Biológica de Oxígeno , Electricidad , Electrólitos , Fotólisis , Luz Solar , Aguas Residuales/químicaRESUMEN
The role of azo dye Reactive Black 5 (RB5) as an electron donor and/or electron acceptor could be distinguished in dual chamber of photocatalytic fuel cell (PFC). The introduction of RB5 in anode chamber increased the voltage generation in the system since degradation of RB5 might produce electrons which also would transfer through external circuit to the cathode chamber. The removal efficiency of RB5 with open and closed circuit was 8.5% and 13.6%, respectively and removal efficiency for open circuit was low due to the fact that recombination of electron-hole pairs might happen in anode chamber since without connection to the cathode, electron cannot be transferred. The degradation of RB5 in cathode chamber with absence of oxygen showed that electrons from anode chamber was accepted by dye molecules to break its azo bond. The presence of oxygen in cathode chamber would improve the oxygen reduction rate which occurred at Platinum-loaded carbon (Pt/C) cathode electrode. The Voc, Jsc and Pmax for different condition of ultrapure water at cathode chamber also affected their fill factor. The transportation of protons to cathode chamber through Nafion membrane could decrease the pH of ultrapure water in cathode chamber and undergo hydrogen evolution reaction in the absence of oxygen which then increased degradation rate of RB5 as well as its electricity generation.
Asunto(s)
Fuentes de Energía Bioeléctrica , Electrones , Naftalenosulfonatos/química , Luz Solar , Compuestos Azo/química , Electricidad , Oxígeno/químicaRESUMEN
The photocatalytic fuel cell (PFC) system was developed in order to study the effect of several operating parameters in degradation of Reactive Black 5 (RB5) and its electricity generation. Light irradiation, initial dye concentration, aeration, pH and cathode electrode are the operating parameters that might give contribution in the efficiency of PFC system. The degradation of RB5 depends on the presence of light irradiation and solar light gives better performance to degrade the azo dye. The azo dye with low initial concentration decolorizes faster compared to higher initial concentration and presence of aeration in PFC system would enhance its performance. Reactive Black 5 rapidly decreased at higher pH due to the higher amount of OH generated at higher pH and Pt-loaded carbon (Pt/C) was more suitable to be used as cathode in PFC system compared to Cu foil and Fe foil. The rapid decolorization of RB5 would increase their voltage output and in addition, it would also increase their Voc, Jsc and Pmax. The breakage of azo bond and aromatic rings was confirmed through UV-Vis spectrum and COD analysis.
Asunto(s)
Suministros de Energía Eléctrica , Electricidad , Naftalenosulfonatos/química , Procesos Fotoquímicos , Contaminantes Químicos del Agua/química , Compuestos Azo/química , Colorantes/química , Electrodos , Luz , Luz SolarRESUMEN
This study investigated the effect of different supporting electrolyte (Na2SO4, MgSO4, NaCl) in degradation of Reactive Black 5 (RB5) and generation of electricity. Zinc oxide (ZnO) was immobilized onto carbon felt acted as photoanode, while Pt-coated carbon paper as photocathode was placed in a single chamber photocatalytic fuel cell, which then irradiated by UV lamp for 24 h. The degradation and mineralization of RB5 with 0.1 M NaCl rapidly decreased after 24-h irradiation time, followed by MgSO4, Na2SO4 and without electrolyte. The voltage outputs for Na2SO4, MgSO4 and NaCl were 908, 628 and 523 mV, respectively, after 24-h irradiation time; meanwhile, their short-circuit current density, J SC, was 1.3, 1.2 and 1.05 mA cm(-2), respectively. The power densities for Na2SO4, MgSO4 and NaCl were 0.335, 0.256 and 0.245 mW cm(-2), respectively. On the other hand, for without supporting electrolyte, the voltage output and short-circuit current density was 271.6 mV and 0.055 mA cm(-2), respectively. The supporting electrolyte NaCl showed greater performance in degradation of RB5 and generation of electricity due to the formation of superoxide radical anions which enhance the degradation of dye. The mineralization of RB5 with different supporting electrolyte was measured through spectrum analysis and reduction in COD concentration.
Asunto(s)
Electricidad , Electrólitos , Contaminantes Ambientales/química , Naftalenosulfonatos/química , Procesos Fotoquímicos , ElectrodosRESUMEN
INTRODUCTION AND HYPOTHESIS: The levator ani is thought to play an important role in sexual function; however, to date little literature has been published on the impact of delivery-related levator trauma on female sexual function. We hypothesised that delivery-related levator trauma has a negative impact on women's reports of pelvic floor and sexual function postpartum. METHODS: In 294 primigravid women with a singleton pregnancy, four-dimensional (4D) translabial ultrasound imaging was used to assess delivery-related levator avulsion and levator hiatal over-distension, and postpartum pelvic floor and sexual function was assessed by an in-house validated questionnaire. Associations between questionnaire responses and levator avulsion and hiatal over-distension were investigated using standard linear modelling methods. RESULTS: Levator avulsion was diagnosed in 14% of women (42 out of 292; 25 unilateral, 17 bilateral) and was found to be significantly associated with lower scores for the pelvic floor integrity and function domain of the questionnaire (P < 0.0005). Avulsion was associated with lower scores for this domain (no avulsion = 2.78, unilateral avulsion = 2.61, bilateral avulsion = 2.29). This association remained significant after controlling for potential confounders (p = 0.013). Avulsion was not associated with any of the other domains of sexual function and levator hiatal over-distension was not associated with scores for any of the questionnaire domains. CONCLUSIONS: The effect of levator avulsion on pelvic floor and sexual function an average of 5.2 months after childbirth seems to be limited to a perception of increased vaginal and pelvic floor muscle laxity, and reduced pelvic floor muscle efficiency. The impact of levator hiatal over-distension on postpartum pelvic floor and sexual function appears to be negligible.