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Chemical absorption method plays an important role in the process of CO 2 separation. One major problem for chemical absorption is huge energy consumption, which is affected by the performance of absorbents. Developing a type of absorbent with high absorption capacity and low regenerative energy consumption is a research topic that attracts attention. The combination of two or more amines is one way to develop new solvents. However, the change of amine liquid ratio can cause a series of complex nonlinear changes in absorption capacity, absorption heat, the heat of vaporisation and sensible heat. It is of interest to visualise the amine solution mixing ratio optimisation to help reduce the energy consumption and increase the absorption capacity. Derivative analysis of standardised vs variables diagram (DSVD), a kind of graphical method based on maximum benefit and minimum consumption, is proposed to determine the optimal mixing ratio of binary amine solution. This novel approach helps to visualise what kind of amines are not suitable for compounding, what kind of amines have the best compounding ratio, and how to determine the optimal compounding ratio. The optimal mixing ratio of the Methyldiethanolamine (MDEA) - Piperazine (PZ) system and MDEA - Monoethanolamine (MEA) were optimised by this method. The optimal ratio of MDEA - PZ and MDEA - MEA are 0.6 (PZ: MDEA = 0.6:0.4, wt.%) and 0.8 (MEA: MDEA = 0.8:0.2, wt.%). • Derivative analysis of standardised vs variables diagram (DSVD) is proposed. • A new method to determine the optimal mixing ratio of binary amine solution. • Multi-objective graphic solution based on benefit and consumption. • The mixing ratio of MDEA + MEA system and MDEA + PZ system was optimised. [ABSTRACT FROM AUTHOR]

Several international institutions have defined background or baseline levels to assess heavy metal concentrations on marine sediments in order to use these values as a reference for sediment quality indices. This criterion for marine sediment quality is applied to evaluate the potential risk of pollutants in aquatic ecosystems. However, those values were established using samples collected in large areas which present specific geochemical conditions. Then there may be a lack of accuracy in the results when using these parameters in other areas. In this context, 15 sediment cores (8 cm diameter; 2 m length) were recovered along the 400 km Asturian coastline, which is an area with representative lithological conditions for the Bay of Biscay, to determine more precise baseline levels for marine sediments from the Bay of Biscay. An evaluation of statistical and empirical methods was done to determine which method delivers the best results. Statistical methods such as mean±2SD and median±2* Median Absolut Deviation (MAD) are strongly influenced by outliers and data distributions which make these approaches less robust. Graphic techniques such as Cumulative Distribution Function (CDF) avoid the problems that asymmetrical data distributions may cause but introduce a certain level of subjectivity in the results due to the baseline values obtained depending on the researcher's experience. Finally, the Probability Curve (CP) method solves issues which may occur when using other techniques and allows one to establish baseline levels based on different percentiles. Regarding the features of the data analysed in this study, the baselines obtained via the CP method with the 95th percentile appear to be the most accurate for the Bay of Biscay. A wide variation has been found between the new baseline values and other international and national levels. Disparity between those levels and the baselines obtained in this study can be generated by granulometric and geological factors. The notable increase in Hg baseline values with respect to OSPAR Background Concentration values (BCs) (0.05 μg g−1 and 0.6 μg g−1 respectively) and the huge different with CEDEX levels and new threshold levels (0.35 μg g−1 and 1.2 μg g−1 respectively) emphasised the relevance of defining specific baselines and threshold levels, as the ones obtained in this study, not only to obtain more precise criteria for marine sediment quality to be used in environmental assessments, but also to propose new threshold levels for the evaluation of dredged material before dumping into ocean sites. • 95th percentile on Probability Curve method determine the most accurate baselines. • Regional geological diversity causes baselines very different from OSPAR. • Natural Hg concentrations were twelve times higher than the OSPAR level. • Recalculated Hg Spanish sediment management level was 3 times the actual value. • Specific baselines and threshold levels are needed to get accurate assessments. [ABSTRACT FROM AUTHOR]

In areas of varying geology, it is difficult to infer water quality from specific conductance or electrical conductivity (EC) data without an understanding of the expected range of EC values based on local bedrock composition. This paper describes a user-friendly graphical screening method that addresses this issue by plotting the EC against concurrent alkalinity data, which correlates well with the presence of carbonate bedrock under natural conditions, and thus serves as an index of bedrock type. The upper limit of EC vs. alkalinity expected in a stream is determined using regional groundwater quality data, based on the assumption that stream chemistry reflects groundwater under baseflow conditions. Stream samples with EC/alkalinity values that consistently plot above this limit are considered impacted by anthropogenic sources. The effect of dilution and runoff on the EC vs. alkalinity plot of stream samples is considered using a simple baseflow/storm runoff-mixing model. The graphical method''s utility as a screening tool is demonstrated by application to stream chemistry data from watersheds of southeastern Pennsylvania and northwestern New Jersey conductivity in several distinct geologic settings; however the method is general and widely applicable to watersheds in humid temperate regions. Its use is intended for watershed stewards of both professional and nonprofessional qualification. [Copyright &y& Elsevier]