Article

# Removal of platinum group metals from the used auto catalytic converter

Metalurgija 01/2009;

Source: DOAJ

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**ABSTRACT:**A new approach towards monuments, considering them as a passive sampler of pollution, is presented. Cultural Heritage objects suffer daily the damages of environmental pollution, especially in those areas interested by heavy traffic. Since monuments undergo only periodic conservation or maintenance works, surfaces are able to accumulate atmospheric deposit and to record changes in its composition. An optimised analytical protocol was developed in order to quantify platinum and rhodium at trace level on surfaces. The two elements have become tracers of automobile emissions in recent years, since the introduction of catalytic converters, and could have catalytic effects on the decay reactions of natural and artificial stone materials. As a first case study, the cement mortar surfaces of a twentieth century monument, the Camerlata Fountain, in Como (Italy) were investigated. The surfaces of the monument were scraped in areas both exposed to atmosphere and sheltered by the architectural elements of the building. The powders were dissolved by microwave-assisted mineralisation with a solution of HCl and HNO(3). The solution was filtered, irradiated and analysed by adsorptive cathodic stripping voltammetry. The powders were also analysed by infrared spectroscopy and X-ray diffraction in order to determine the chemical and mineralogical composition. An analysis protocol was set up considering the matrix effect and the expected low concentrations of the two metals. The results enlightened variable concentration values and distribution areas of platinum (0.013-45 μg/kg) and rhodium (0.55-274.4 μg/kg), suggesting the ability of artificial stone surfaces to accumulate the two elements. The sample chemical and mineralogical composition was consistent with a typical cement plaster interested by decay phenomena. This work investigated the relation between Cultural Heritage and pollution by another point of view. The analytical protocol presented in this paper was effective in determining platinum and rhodium in traces on the investigated stone surfaces with negligible matrix effects. The presence of platinum and rhodium on monument surfaces should be of significant interest when planning Cultural Heritage conservation. A better knowledge of the role of the two metals in decay phenomena could impact in a positive way artwork conservation.Environmental Science and Pollution Research 02/2011; 18(2):184-91. · 2.62 Impact Factor -
##### Conference Paper: The efficient algorithm for optimal capacity expansion of satellite links in mobile networks

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**ABSTRACT:**A deterministic expansion model for sizing of N satellite links in mobile networks during exploitation is being developed. The model is applied to short- or medium-term planning with finite number of discrete time periods. In the planning process it can help the Land Earth Station Operator (LESO) to find the optimal capacity-expansion policy for new constructions and conversions of channel equipment that minimizes the total cost. The model for the capacity expansion problem with shortages (CEPS) allows capacity conversions from one satellite link to another in both directions, but limitations can be imposed. Furthermore, upper bounds on shortages and idle capacities can be imposed. The traffic demand increments for additional capacity in any time period and for any link can be negative. All cost functions are assumed to be piecewise concave and non-decreasing away from zero. Using a network flow approach the paper develops an efficient dynamic-programming algorithm to minimize the total expansion cost. An heuristic algorithm is tested on many examples, and its efficiency is compared with an algorithm based on an exact approachEUROCON'2001, Trends in Communications, International Conference on.; 02/2001

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