Name: LARISSE SUZY SILVA DE OLIVEIRA
Publication date: 05/02/2019
Advisor:
Name |
Role |
|---|---|
| LUCIANA HARUE YAMANE | Advisor * |
| RENATO RIBEIRO SIMAN | Co-advisor * |
Examining board:
| Name |
Role |
|---|---|
| LUCIANA HARUE YAMANE | Advisor * |
| MARIA TEREZA WEITZEL DIAS CARNEIRO LIMA | External Examiner * |
| RENATO RIBEIRO SIMAN | Co advisor * |
Summary: In recent years, due to the technological innovations that have brought about cost
reductions, the growth of the photovoltaic sector has stood out among the renewable
sources of energy. As a consequence, by the year 2050 it is estimated that 78 million
tons of photovoltaic panels will need to be discarded in the world and about 750
thousand tons in Brazil alone. Silicon photovoltaic panels, most used worldwide, are
composed of aluminum frame, tempered glass, silicon photovoltaic cell with metal
filaments, encapsulating material and backsheet polymer material. The main metals
present in the photovoltaic panels are: aluminum, zinc, lead, copper, indium, selenium,
tellurium, cadmium and silver. Considering that the recycling should be stimulated from
the environmental point of view and at the same time economically advantageous from
an economic aspect, this study aimed to verify the technical viability of the silver
recovery of photovoltaic cells using acid leaching, followed by the evaluation of the
chemical and electrochemical precipitation processes to evaluate their efficiencies. To
do so, the gravimetric composition of three photovoltaic panels and the concentration
of metals (Ag, Al, Pb, Cu and Fe) in the photovoltaic cells were determined.
Subsequently, the concentration factors of HNO3 (1-10M) and temperature (25-60oC)
in the silver leaching process were verified using the Rotational Central Compound
Design (DCCR) method for the experimental design. Finally, for the best experimental
conditions, it was verified the ideal reaction time and the best way to recover the silver
present in the photovoltaic cells tested. After the statistical treatment of the results, it
was possible to solubilize 100% of the silver contained in the photovoltaic cells, being
the optimized parameters: temperature of 55oC, concentration of HNO3 of 2,3M and
reaction time of 2h. Chemical precipitation by addition of HCl as well as
electroprecipitation made it possible to extract more than 99% of silver in solution.
Thus, considering all the route used, the recovery of 99.98% of the silver present in
the photovoltaic cells was obtained.
