The reaction of HCHO with Beijing winter's real ambient particulate matter(PM) inside a 3.3 m^3 Teflon Chamber was conducted in this study. NO_2, O_3 and H_2O gases were removed from the ambient aerosol before entering into the chamber. The decays of HCHO were monitored(acetylacetone spectrophotometry method) during the reactions at different PM number concentrations(N_a) and relative humidities(RHs), and the formed particulate formate was detected by IC and XPS techniques. The results showed that when RH was10%–15%, the decay rate of HCHO in the chamber was higher with the existence of PM from relatively clean days(with number concentration(N_a) < 200,000 particle/L, 0.35–22.5 μm)compared to dirty days(N_a> 200,000 particle/L, 0.35–22.5 μm). When RH increased to 30%–45%, PM can hardly have significant influences on the decay of HCHO. The formations of formate on the reacted PM were consistent with the HCHO decay rates at different ambient PM N_aand RH conditions. This is a first study related to the "real" ambient PM reacted with HCHO and suggested that in the clean and low RH days, PM could be an effective medium for the conversion of HCHO to formate.
We designed photoelectrochemical cells to achieve efficient oxidation ofrhodamine B (RhB)without the need for photocatalyst or supporting electrolyte.RhB,the metal anode/cathode,and O2 formed an energy-relay structure,enabling the efficient formation of O2^- species under ultraviolet illumination.In a single-compartment cell (S cell)containing a titanium (Ti)anode,Ti cathode,and 10mg·mL^-1 RhB in water,the zero-order rate constant of the photoelectrochemical oxidation (kPEC)of RhB was 0.049mg·L^-1·min^-1,while those of the photochemical and electrochemical oxidations of RhB were nearly zero.kPEC remained almost the same when 0.5mol·L^-1 Na2SO4 was included in the reactive solution,regardless of the increase in the photocurrent of the S cell.The kpEc of the illuminated anode comoartment in the two-compartment cell,including a Ti anode,Ti cathode,and 10mg·mL^-1 RhB in water,was higher than that of the S cell.These results support a simple,eco-friendly,and energy saving method to realize the efficient degradation of RhB.
