ADSORPTION ESSAYS OF PALLADIUM IN MODIFIED SILICA GEL WITH THIOURONIUM GROUPS

What is it about?

The silylant 3-cloropropyltriethoxysilyl was anchored over silica gel in anhydrous conditions in order to react with thiourea to obtain modified silica gel with thiouronium. The aim to obtain an inorganic support that is able to hijack metals from the VIII group such as palladium. The product was characterized by Sbet and FTIR infrared spectroscopy. For the determination of the structure in the modified silica gel NMR spectra of silicon and carbon were preformed in solid state. The coordination form of the modified silica gel to the metal was studied computationally in the context of the DFT theory, using the ADF code. This was a collaborative work with "Fundación Chile" for the recuperation of precious metals from the mining industry.

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Why is it important?

The objective of this work is to restore the minerals with added value that are used in the process of the Chilean mines by giving them a third treatment, implementing a modified inorganic support with an organic chain with coordinated groups. The thiouronium group has been used in organic resins for the recuperation of metals with added value. The modification of inorganic supports, such as silica gel, has been often used in the areas of heterogeneous catalysis, ionic chromatography and chemisorption of metals of interest and in several industrial applications , because of its chemical stability towards extreme pH conditions and temperature. Silica gel is an inorganic support constituted by a skeleton of silicon and oxygen, whose union is called siloxans Si-O-Si. These bonds are randomly distributed establishing a great number of silanols Si-OH. The modification of the surface of silica gel has the objective to link in one material the properties of an inorganic support with an organic chain. This process is known as functionalization. The modified of the silica gel with the thiouronium group from the modified silica with the 3-chloropropyl group and thiourea provide a cheaper support in order to make a gradual upgrade to a bank level for the recovery of the metals, along with a chemical process that allows this recovery, presenting the development of new technologies at a low price. Computational studies were performed in the framework of the theory of functional density , in order to propose a coordination model to the studied metal, whose analysis of the internal energy structure allows formulating a criterion to discern the coordination formula.