Dye decolorization and energy recovery of photocatalytic fuel cell subjected to optimization of supporting electrolyte concentration and external resistance

The concentrations of supporting electrolyte and external resistance (R-ext) played crucial roles to improve photocatalytic fuel cell (PFC) efficiency. Herein, the significant influence of Na2SO4 concentration (0.05-0.20 M) and the R-ext (100, 280, 500, 1000 and 10,000 Omega) on the power production and dye decolorization in PFC were addressed. Analysis of variance (ANOVA) revealed that the further increment of 0.10 M of Na2SO4 concentration only enhanced maximum power density (Pmax) but had no significant effect on the dye decolorization (P > 0.05). Conversely, the result showed distinct differences in PFC performances under different R-ext (P < 0.05). The PFC operated with R-ext of 280 Omega from the maximum power point (RMPP) yielded the highest Pmax of 11.85 +/- 0.45 mu W cm(-2) and decolorization rate of 0.51 h(-1) with a total chemical oxygen demand (COD) removal of 88.82 +/- 3.70%. Interestingly, it was discovered that the P-max was significantly enhanced by the impedance-matching of R-ext with R-MPP while the decolorization rate was inversely proportional to R-MPP. Besides, the dynamic behavior of PFC was associated with the polarization study which the main internal losses contributor was examined. Additionally, the present study provided insight into the toxicity reduction of the treated dye solution through simple phytotoxicity test by using lettuce seed bioassays.

Automated summary

The study found that the concentrations of supporting electrolyte and external resistance were crucial to the efficiency of a photocatalytic fuel cell, with increasing Na2SO4 concentration leading to higher power density, and matching external resistance significantly enhancing power density but decreasing dye decolorization rate.