The presence of inorganic and organic substances may alter the physicochemical properties of iron (Fe) salt precipitates, thereby stabilizing the antimony (Sb) oxyanions in potable water during the chemical treatment process. Therefore, the present study aimed to examine the surface characteristics, size of Fe flocs and coagulation performance of Sb oxyanions under different aqueous matrices. The results showed that surface properties of Fe flocs significantly varies with pH in both Sb(III, V) suspensions, thereby increasing the mobility of Sb(V) ions in alkaline conditions. The negligible change in surface characteristics of Fe flocs was observed in pure water and Sb(III, V) suspension at pH 7. The key role of Van der Waals forces of attraction as well as hydration force in the aggregation of early formed flocs were found, with greater agglomeration capability at higher more ferric chloride dosage. The higher Sb(V) loading decreased the size of Fe flocs and reversed the surface charge of precipitates, resulting in a significant reduction in Sb(V) removal efficiency. The competitive inhibition effect on Sb(III, V) removal was noticed in the presence of phosphate anions, owing to lowering of ζ-potential values towards more negative trajectory. The presence of hydrophobic organic matter (humic acid) significantly altered the surface characteristics of Fe flocs, thereby affecting the coagulation behavior of Sb in water as compared to the hydrophilic (salicylic acid). Overall, the findings of this research may provide a new insight into the variation in physicochemical characteristics of Fe flocs and Sb removal behavior in the presence of inorganic and organic compounds during the drinking water treatment process. 相似文献
We suggest a method to detect that two periodic knots are not equivariantly concordant, using surgery on factor links. We construct examples which satisfy all known necessary conditions for equivariant slice knots- Naik's and Choi-Ko-Song's improvements of classical results on Seifert forms and Casson-Gordon invariants of slice knots - but are not equivariantly slice.
1. IntroductionIn studying many problems arising in science and engineering, we need to estimate parameters in governing differential equations. Some theoretical results for this kind of inverseproblems can be found in various literatu-res, e.g., see [1-4]. Also, there have been a lot ofwork concerning their numerical approalmations, e.g., see [5-10]. One of numerical methods is the so-called optimization method as in is]. To do this, we first guess the unknownparameters in some ways, and the… 相似文献
Nematic lyomesophases with discotic (ND) and cylindrical (NC) micelles in complex multicomponent lyotropic systems based on alkyltrimethylammonium bromide detergents have been identified by the 1H-2H-, and 13C-NMR methods and polarizationoptical microscopy. The difference in the structures of the ND and NC nematic phases is especially pronounced in the 13C-NMR spectra. Addition of chiral dopants to the lyomixture facilitates formation of the ChD and ChC cholesteric phases. According to the 13C-NMR spectra, the micellar mobility in the cholesteric lyomesophases decreases in comparison with the nematic ones. The alignment of lyocholesterics under the action of an external magnetic field is found. 相似文献
The Pluronic F127 triblock copolymer was end‐capped by carboxyl groups using a degradable oligolactide as a spacer to confer pH‐ and thermo‐sensitive properties. With increasing chain length of the oligolactide, the temperature‐dependent sol‐gel transition curve was significantly shifted to higher concentration with concomitant narrowing of the gelation temperature range. Carboxylic acid end‐capped Pluronic also exhibited a peculiar pH‐dependent sol‐gel transition behavior. At 37 °C, sharp gel‐to‐sol and sol‐to‐gel transitions were observed around pH = 4.8 and 8.2, respectively. The pH‐dependent phase transition was caused by introduction of carboxylic acid groups at the ends of Pluronic F127.
Steaming ginseng at high temperature increased its cytotoxicity to SK-Hep-1 hepatoma cancer cells. HPLC separation and fractionation followed by MTT assay revealed that ginsenosides Rg3, Rg5, Rk1, Rs5, and Rs4 are the active principles. Their 50% growth inhibition concentration (GI50) values were 41, 11, 13, 37, and 13 microM, respectively. Cisplatin had a GI50 of 84 microM in the same assay conditions. 相似文献