Banca de DEFESA: PAULO ROBERTO FERREIRA DE BRITO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : PAULO ROBERTO FERREIRA DE BRITO
DATA : 08/06/2022
HORA: 14:00
LOCAL: https://conferenciaweb.rnp.br/webconf/dalmo-2
TÍTULO:

 

Development of a Self-Sustainable Process for the Recovery of Nickel in Industrial Waste from Solutions for Autocatalytic Deposition

PÁGINAS: 110
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Cinética Química e Catálise
RESUMO:

The surface treatment industry has presented increasingly sophisticated technological solutions, such as, for example, nickel deposition by an autocatalytic process (electroless). However, these solutions have a certain lifespan, requiring their disposal after a certain period of use. The treatment of industrial waste from solutions for the deposition of Ni and P by an autocatalytic process (electroless) for disposal presents difficulties, mainly due to the presence of the complexing agents used in the formulation of the solutions, which make it impossible for nickel to precipitate in the effluent, for future disposal (or reuse). This work proposes a self-sustainable methodology for the removal and recovery of nickel from these residues. The removal and recovery of the nickel present in this type of solution was carried out by the reduction of Ni²⁺ to Ni⁰, being initially studied in a synthetic effluent, containing Ni⁺² (5.8 g/L), sodium hypophosphite (reducing agent, 24 g/L), in addition to stabilizers and buffers. To determine the best reactional conditions for Ni⁰ precipitation, several experiments were carried out, based on the operating parameters of solutions for the deposition of Ni by the autocatalytic process in the industry, and additionally using statistical tools, as an experimental design 2³. The catalyst  was added to the effluents (2.0 g), starting the reaction. Throughout the tests, the pH of the solutions was maintained at 7.0 or allowed to vary spontaneously. The experiments were carried out under magnetic or mechanical agitation. The study of the efficiency of the Ni²⁺ reduction reactions in the effluents was based on the residual concentration of Ni²⁺ (by analysis via ICP-OES) in the samples collected at different times. A reduction of up to 99.9% in the amount of Ni²⁺ in the effluent was observed after 30 min of reaction, when the virgin catalyst was used, in experiments under magnetic stirring. The reduced Ni was separated from the effluents by magnetic filtration, followed by washing in distilled water, ethyl alcohol and drying, to be subjected to characterization by SEM-EDS, XRD and DLS. The characterization of the recovered metal revealed that it consists of agglomerates of metallic Ni containing between 5.4 and 8.0% phosphorus. The study of the data obtained by the analysis of Ni²⁺ in the samples collected during the experiments showed that the initial amount of Ni²⁺ in the synthetic and industrial effluent was 5.8 g/L and 3.2 g/L, respectively. The system developed in this first stage of the work was later applied to industrial effluent, obtained from a batch of solution for the deposition of nickel layers by an autocatalytic process whose end of life was reached, with unknown composition, but which had its content of [Ni²⁺] (3.2 g/L) and NaH₂PO₂ (13.5 g/L) evaluated by ICP-OES and volumetric analysis, respectively. To conduct these comparative tests, the concentration of NaH₂PO₂ in the industrial effluent was adjusted to a value identical to that of the synthetic effluent. The results were similar to those obtained with the synthetic effluent, with a reduction in the amount of Ni²⁺ of up to 99.9% after 30 min of reaction. Additionally, this work points to the possibility of using high purity H₂, obtained simultaneously with the recovery of Ni in solution residues for autocatalytic deposition.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1762430 - DALMO MANDELLI
Membro Titular - Examinador(a) Interno ao Programa - 1838759 - JANAINA DE SOUZA GARCIA
Membro Titular - Examinador(a) Interno ao Programa - 2351974 - JULIANA DOS SANTOS DE SOUZA
Membro Titular - Examinador(a) Externo à Instituição - PEDRO SERGIO FADINI - UFSCAR
Membro Titular - Examinador(a) Externo à Instituição - MARCOS ROBERTO DE VASCONCELOS LANZA - USP
Membro Suplente - Examinador(a) Interno ao Programa - 1814655 - LUCIA HELENA GOMES COELHO
Membro Suplente - Examinador(a) Externo ao Programa - 1305186 - SERGIO BROCHSZTAIN
Membro Suplente - Examinador(a) Externo à Instituição - ROCHEL MONTERO LAGO