Removal of pollutants by enhanced coagulation combined PAC with variable charge soils: flocs' properties and effect of pH.

This study investigated the properties of flocs and effects of the solution pH on removal of representative pollutants by enhanced coagulation with variable charge soils of South China and polyaluminum chloride (PAC). The results demonstrated that the removal efficiency of turbidity was larger and the aggregated flocs had a faster growth rate, bigger size, denser structure and faster settling rate than those generated by PAC alone, when variable charge soil was used in conjunction with PAC. Additionally, initial solutions pH had meaningful effects on removal of pollutants. With the increase in the pH of the solution, the removal efficiencies of turbidity, algae and heavy metal ions significantly increased. Besides, charge neutralization together with physical entrapment of colloids was the dominant mechanism in enhanced coagulation, and variable charge soil displayed a great adsorption effect.

[Effects of Anions on Bromate Formation During Ozonation of Bromide-Containing Water].

To study the effects of common inorganic anions on bromate formation during ozonation of bromide-containing water, the effects of different mass concentrations of Cl-, HCO3-, and SO(4)2- on bromate formation were investigated in bench-scale test. The mechanisms of these three coexisting anions on bromate formation was analyzed based on the ozone decomposition, HOBr/OBr- formation, and transformation of total bromine species. Our results showed that adding of 3-150 mg.L-1 Cl- can reduce 8. 8%-25. 7% of bromate formation within 60 min. 63. 9% of bromate would be decreased by increasing SO(4)2- concentration from 0 mg.L-1 to 30 mg.L-1 within 20 min. However, more than 6. 4 times the mass concentrations of bromate were formed as HCO3- mass concentrations increased from 0 mg.L-1 to 30 mg.L-1 within 20 min. The production of bromate was slightly increased when HCO3- mass concentrations was above 30 mg.L-1. Under the condition of the same ozone dosage and reaction time, adding of Cl- and SO(4)2- will inhibit the formation of bromate during ozonation, while adding of HCOC3- significantly will increase the production of bromate.

Prediction of liquid chromatography retention factors for alpha-branched phenylsulfonyl acetates using quantum chemical descriptors.

The logarithms of retention factors normalized to a hypothetical pure water eluent (log kw) were determined on a reversed-phase high-performance liquid chromatography(RP-HPLC) column (Li Chrosorb RP-18 column) for 20 new alpha-branched phenylsulfonyl acetates. The atomic charge method was applied to develop quantitative structure-retention relationships (QSRRs). Among the available geometric and electronic descriptors, surface area (S), ovality (O), and the charge of carboxyl group (Qoc) are significant. In the model, the contribution of surface area (S) is the greatest. The molecular mechanism of retention was demonstrated through the model. With the correlation coefficient (r2adj, adjusted for degrees of freedom) of 0.964, the standard error of 0.164 and the F-value of 170.39, the model has good predictive capacity.