Equivalent concentration

Abstract: STAINLESS STEEL SURFACES ARE TREATED WITH AN AQUEOUS SOLUTION CONTAINING PHOSPHORIC IONS EQUIVALENT TO 145 580 G./LITRE OF PHOSPHORIC ACID, NITRATE IONS EQUIVALENT TO 17-85 G./LITRE OF NITRIC ACID, CHLORINE IONS EQUIVALENT TO 16-80 G./LITRE OF HYDROCHLORIC ACID, SULFOSALICYLATE IONS EQUIVALENT OT 1-10 G./LITRE OF SULFOSALICYLIC ACID AND SMALL AMOUNTS OF OPTICAL COMPOUNDS SELECTED FROM THE GROUP OF WATER SOLUBLE POLYMER, AROMATIC AMINO COMPOUNDS, SURFACTANT, LIGNINSULFONIC ACID AND SALTS THEREOF, SULFURIC ACID AND ACIDS HAVING EQUIVALENT CONCENTRATION OF 4.0 N-18 N.

Abstract: The extent of remediation of contaminated industrial sites depends on spatial heterogeneity of contaminant concentration and spatially explicit risk characterization. We used sequential Gaussian simulation (SGS) and indicator kriging (IK) to describe the spatial distribution of polycyclic aromatic hydrocarbons (PAHs), pH, electric conductivity, particle aggregate distribution, water holding capacity, and total organic carbon, and quantitative relations among them, in a creosote polluted soil in southern Sweden. The geostatistical analyses were combined with risk analyses, in which the total toxic equivalent concentration of the PAH mixture was calculated from the soil concentrations of individual PAHs and compared with ecotoxicological effect concentrations and regulatory threshold values in block sizes of 1.8 x 1.8 m. Most PAHs were spatially autocorrelated and appeared in several hot spots. The risk calculated by SGS was more confined to specific hot spot areas than the risk calculated by IK, and 40-50% of the site had PAH concentrations exceeding the threshold values with a probability of 80% and higher. The toxic equivalent concentration of the PAH mixture was dependent on the spatial distribution of organic carbon, showing the importance of assessing risk by a combination of measurements of PAH and organic carbon concentrations. Essentially, the same risk distribution pattern was maintained when Monte Carlo simulations were used for implementation of risk in larger (5 x 5 m), economically more feasible remediation blocks, but a smaller area became of great concern for remediation when the simulations included PAH partitioning to two separate sources, creosote and natural, of organic matter, rather than one general.

Abstract: Conductivities of the aqueous solutions of nearly thirty samples of Graham's salt having different molecular weights have been observed. Plots of equivalent conductivity (Λ) against square root of equivalent concentration (C 1/2) show a strong curvature at lower concentration reminiscent of the behaviour of weak electrolytes. It has been explained as being due to the association of counter-ions with poly-ions because of a high charge density around the latter. The rise in equivalent conductance with decrease in concentration is more pronounced in the case of low-molecular-weight samples. In high molecular-weight compounds the molecular weight dependance is less conspicuous. On plotting equivalent conductance against weight-average molecular weight for any particular concentration of Graham's salt, curves have been obtained which show that with an increase in molecular weight conductivity falls first sharply and then slowly. The effect of the weight-average molecular weight on conductivity is much more pronounced than that of the corresponding endgroup molecular weight, although the values of the latter also affect the conductance. The highly curved plots of Λ vs. C 1/2 can be reduced to linear ones on a log-log scale. A plot of specific conductivity against the equivalent concentration is also invariably linear. The values of ‘apparent basicity’ calculated for various samples of Graham's salt with the help of Ostwald's rule lie between 2 and 3; they have a tendency to decrease with increase in weight-average molecular weight.