**3. Results and discussion**

*Trace Metals in the Environment - New Approaches and Recent Advances*

**Element Ppm** Au 45.93 Pd 1.92 Pt 0.005 Ce 81.79 Nd 56.97 La 51.89 Yb 33.35 Tb 25 Ge 9 Ga 2.5 Sm 1.75 Er 0.9 Eu 0.35

dilution factor. With this, all the elements fell in a range of concentration below 1 ppm for the case of Au, Ce, Nd, L, Tb, Ge, and Yb. For the rest of the elements, a direct sample was taken using standards between 1 and 5 ppm (without dilution).

*Chemical composition of the leaching liquors of the SEDEX mineral, done by ICP.*

The analytical methods used for the characterizations of the different mineral used to the ion exchange stage were characterized by dry granulometric analysis using a standard sieves (Tyler series); X-ray diffraction using an INEL equinox 2000 equipment was located at the Autonomous University of the State of Hidalgo (AUSH), and the spectra was obtained with a Cu Kα1 radiation of wave length of 1.50056 Å, a voltage of 30 kV, an intensity of 20 mA, and a sweep speed of 22 θ/ min, which were then treated with the software MATH to identify the mineral spe-

Then, to determine the chemical composition of standard solutions and leached liquors (before and after ion exchange), an inductively coupled plasma spectrophotometer (ICP-OES) Perkin Elmer brand/model 2100 located at the AUSH was used. In the same way, scanning electron microscopy (SEM) was used to determine morphology and particle type of minerals, using a JEOL brand microscope model JMS6300, having an Energy Dispersive Spectrometer of X-ray (EDS) for chemical microanalysis and also located at the AUSH. And finally, X-ray fluorescence (XRF) was executed to determine the chemical composition of minerals before and after the ion exchange procedure, and for this analysis, a portable spectrophotometer of X-ray brand BRUKER, model S1 TITAN was used, also using the GeoChem calibration software (equipment located at the National Autonomous University of Mexico).

**206**

**2.3 Analytical methods**

**Table 1.**

**ICP analysis**

*2.3.1 Characterization of minerals*

cies contained in each material.

*2.3.2 Chemical analysis*
