Oxidative decomposition of p-nitroaniline in water by solar photo-Fenton advanced oxidation process.

The degradation of p-nitroaniline (PNA) in water by solar photo-Fenton advanced oxidation process was investigated in this study. The effects of different reaction parameters including pH value of solutions, dosages of hydrogen peroxide and ferrous ion, initial PNA concentration and temperature on the degradation of PNA have been studied. The optimum conditions for the degradation of PNA in water were considered to be: the pH value at 3.0, 10 mmol L(-1) H(2)O(2), 0.05 mmol L(-1) Fe(2+), 0.072-0.217 mmol L(-1) PNA and temperature at 20 degrees C. Under the optimum conditions, the degradation efficiencies of PNA were more than 98% within 30 min reaction. The degradation characteristic of PNA showed that the conjugated pi systems of the aromatic ring in PNA molecules were effectively destructed. The experimental results indicated solar photo-Fenton process has more advantages compared with classical Fenton process, such as higher oxidation power, wider working pH range, lower ferrous ion usage, etc. Furthermore, the present study showed the potential use of solar photo-Fenton process for PNA containing wastewater treatment.

Effects of sodium citrate on melamine-cyanuric acid mixture-induced urolithiasis in rats.

BACKGROUND: When melamine is used as an additive in infant formula, it may cause acute nephrotoxicity in humans as well as in other animals. This study was designed to examine the effects of a melamine-cyanuric acid mixture on cytotoxicity in vitro and rat-acute nephrotoxicity. METHODS: In the in vitro study, crystal formations created by the melamine-cyanuric acid mixture were evaluated in media with differing pH conditions over a 24-h period and co-treatment with sodium citrate to observe the crystal formation. In the animal study, rats were exposed to a melamine-cyanuric acid mixture (400 mg/kg, 1:1) via oral gavage 14 days and co-treated with sodium citrate to observe the crystal formation in rats. RESULTS: Melamine-cyanuric acid mixture-induced crystal was pH dependent in a conditioned medium, and sodium citrate could decrease the crystal formation. Melamine-cyanuric acid-treated rats showed marked kidney swelling, vacuolization and necrosis in the proximal tubules, and numerous polarizable crystals were located in the distal segments, causing increases in kidney weight, serum BUN and creatinine. After co-treatment with sodium citrate, these increases can all be reversed. Moreover, the degrees of nephrotoxicity, proliferating of cell nuclear antigen protein and urolithiasis-related osteopontin were also decreased in the kidneys. CONCLUSION: Sodium citrate could decrease melamine-cyanuric acid mixture-induced crystal formation that leads to urolithiasis and nephrotoxicity in rats. These results may provide a strategy for melamine-cyanuric acid-intoxication therapy in animal.