To gain information on organic pollutants in wateresediment systems, a compartment model was applied to study the sorption course of phenanthrene and pentachlorophenol (PCP) in sediments. The model described the time-dependent interaction of phenanthrene and PCP with operationally defined reversible and irreversible (or slowly reversible) sediment fractions. The interactions between these fractions were described using first order differential equations. By fitting the models to the experimental data, apparent rate constants were obtained using numerical optimization software. The model optimizations showed that the amount of reversible phase increased rapidly in the first 10d with the sorption time, then decreased after 10d, while the amount of irreversible phase increased in the total sorption course. That suggested the mass transport between reversible phase and irreversible phase. The extraction efficiency with hot methanol ranged from 36% to 103% for phenanthrene and from 65% to 101% for PCP, with the trend of decreasing with sorption time.

The perennial herb Phytolacca acinosa Roxb. (Phytolaccaceae), which occurs in Southern China, has been found to be a new manganese hyperaccumulator by means of field surveys on Mn-rich soils and by glasshouse experiments. This species not only has remarkable tolerance to Mn but also has extraordinary uptake and accumulation capacity for this element. The maximum Mn concentration in the leaf dry matter was 19, 300mg/g on Xiangtan Mn tailings wastelands, with a mean of 14, 480mg/g. Under nutrient solution culture conditions, P. acinosa could grow normally with Mn supplied at a concentration of 8000mmol/l, although with less biomass than in control samples supplied with Mn at 5 mmol/l. Manganese concentration in the shoots increased with increasing external Mn levels, but the total mass of Mn accumulated in the shoots first increased and then decreased. At an Mn concentration of 5000mmol/l in the culture solution, the Mn accumulation in the shoot dry matter was highest (258 mg/plant). However, the Mn concentration in the leaves reached its highest value (36,380mg/g) at an Mn supply level of 12,000mmol/l. These results confirm that P. acinosa is an Mn hyperaccumulator which grows rapidly, has substantial biomass, wide distribution and a broad ecological amplitude. This species provides a new plant resource for exploring the mechanism of Mn hyperaccumulation, and has potential for use in the phytoremediation of Mn-contaminated soils.

In this paper, the effects of various inorganic anions (NO3−, Cl−, SO4 2−, HCO3−, H2PO4−) on the photodegradation of an azo dye, acid orange 7 (AO7) were investigated under UV or visible light irradiation in the presence of TiO2 particles. The effects of inorganic anions on the photodegradation of AO7 under visible light irradiation were significantly different from UV irradiation pathway. In TiO2/UV system, inorganic anions inhibited the photodegradation of the dye by their trapping hydroxyl radicals. In TiO2/Vis system, the observed inhibition effects of inorganic anions can be interpreted by competitive adsorption. In addition, the results indicated that the photodegradation of AO7 took place mainly in the bulk solution under UV light irradiation, while under visible light irradiation, the reaction occurred on the catalyst surface.

In this paper, silica gel supported titanium dioxide particles (TiO2/SiO2) prepared by acid-catalyzed sol-gel method was as photocatalyst in the degradation of acid orange 7 (AO7) in water under visible light irradiation. The particles were characterized by X-ray diffraction, BET specific surface area determination, and point of zero charge measurement. The supported catalyst had large surface area, high thermal stability and good sedimentation ability. The photodegradation rate of AO7 under visible light irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The photodegradation rate of AO7 using 31% TiO2/SiO2 particles was faster than that using P-25 and TiO2 (Shanghai) as photocatalyst by 2.3 and 12.3 times, respectively. The effectof the calcination temperature and the TiO2 loading on the photoactivity of TiO2/SiO2 particles was also discussed.

Titanium dioxide mediated photocatalytic degradation of polyvinyl alcohol (PVA) was studied in an annular photoreactor with two 6W (Emax=365nm) UV lamps as light source. In the presence of both TiO2 and light, and initial concentration of 30mg/l, 55.3% of PVA was found to degrade after an hour. The effects of initial concentration, pH and the addition of H2O2 on the rate of degradation of PVA were studied. The results showed that it was more effective for PVA to be degraded under acidic or alkaline condition. The order of reaction rates was pH10>pH9>pH4>pH5> pH7. Proper amount of H2O2 could improve the photodegradation rate of PVA. However, the further increase of H2O2 might inhibit the system efficiency. Fourier transformed infrared spectroscopy (FTIR) indicated that several carbon-carbon bonds were scissored, which led to the formation of short-chain compounds during the photocatalytic oxidation of PVA. These intermediates were also degraded with prolonged reaction.