Comparative equilibrium studies of sorption of Pb(Ⅱ) ions by sodium and calcium alginate

The absorption of Pb(Ⅱ) ions from aqueous solution by different alginate compounds was studied in a batch sorption system.Water soluble sodium alginate and insoluble calcium alginate beads were investigated.The lead-binding capacity of both alginate compounds was highest within the pH range 6-8.The binding capacities and rates of Pb(lI) ions by alginate compounds were evaluated.The Langmuir,Freundlich,and Bruneaur,Emmet and Teller (BET) sorption models were applied to describe the isotherms and isotherm ...     

An overview of systems analysis methods in delineating environmental quality indices

Environmental quality indices (EQIs) have been developed for a variety of purposes ranging from enforcement of environmental standards, to analysis of trends of environmental degradation or improvement, to scientific research. EQIs currently in use are not organized within an integrated framework and thus it has been difficult to analyze adequately complex, multidisciplinary, large-scale, global phenomena. In this paper we compare four different approaches to developing EQIs within a systems perspective. Our analysis suggests that: (1) non-linear regression models that represent an ecosystem's response to different impacts within a stress-response framework (method of response functions) are useful tools for analysis of environmental data; (2) non-equilibrium thermodynamics models based on the concept of exergy, which represents the free energy a system possesses in relation to its environment, provide a common basis for representing many aspects of ecosystem development and response to environmental impacts as a single measure; (3) diagram models based on the concept of emergy, which represents both environmental values and economic values with a single measure, provide a common basis for integrating economic development and environmental protection values into one index; and (4) complex systems simulation models based on general systems theory, which use the methodologies of systems analysis and simulation to identify, quantify, and interrelate EQIs within a dynamic systems context, provide explicit linkages between causes and effects (vertical integration) and identify cross-linkages among different environmental issues (horizontal integration).     

COVID-19 pandemic: environmental and social factors influencing the spread of SARS-CoV-2 in São Paulo,Brazil

Environmental Science and Pollution Research - The new coronavirus SARS-CoV-2 has infected more than 14 million people worldwide so far. Brazil is currently the second leading country in number of...     

Removal of Pb(II) from water using keratin colloidal solution obtained from wool

The aim of this study is to investigate the use of keratin colloidal solution, which was obtained from wool, for the removal of Pb(II) from water. The addition of keratin colloidal solution (15 g L^?1, 0.30 mL) to a Pb(II) solution (1.0 mM, 0.90 mL, pH 5.0) resulted in the formation and precipitation of a Pb–keratin aggregate. Measurement of the Pb(II) and protein concentrations in the supernatant solution revealed that 88 and 99 % of the Pb(II) and keratin protein were removed from the solution, respectively. The maximum Pb(II) uptake capacity of keratin in the colloidal solution was 43.3 mg g^?1. In addition, the Pb–keratin aggregate was easily decomposed via the addition of nitric acid, which enabled the recovery of Pb(II). However, aggregation did not occur in solutions with Pb(II) concentrations below 0.10 mM. Therefore, we used a keratin colloidal solution encapsulated in a dialysis cellulose tube to remove Pb(II) from 0.10 mM solutions, which enabled the removal of 95 % of the Pb(II). From these results, we conclude that keratin colloidal solution is useful for the treatment of water polluted with Pb(II).     

Dual oil concentration estimates in ecologically sensitive zones

Propagation of the oil spilling from a damaged oil tanker is considered in a limited sea area. Direct and adjoint estimates of the average oil concentration in special zones are derived by using solutions of the 2-D main and adjoint oil transport problems, respectively. The dual estimates complement each other nicely in studying the oil spill consequences. While the direct estimates are preferable to get a comprehensive idea of the oil spill impact on the whole area, the adjoint ones are specially useful and economical when the accident site-dependence or/and the oil spill rate-dependence of the oil concentration is/are studied only in a few ecologically sensitive zones. Indeed, each adjoint estimate explicitly relates the average oil concentration in a zone to the oil spill rate using the adjoint solution values at the accident site. Being independent of the two parameters (the accident site and oil spill rate), the adjoint solution can be found for each zone regardless of a concrete accident and used repeatedly for various possible values of these parameters. Several examples explain how to decide between two estimates.Thanks to special boundary conditions, the main and adjoint problems are both well-posed according to Hadamard (1923). The dual estimates can be generalized to the three dimensions. The balanced, absolutely stable and compatibie main and adjoint 3-D numerical algorithms by Skiba (1993) can easily be adapted to the problem discussed here.