Banca de QUALIFICAÇÃO: POLLYANNA VANESSA DOS SANTOS LINS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : POLLYANNA VANESSA DOS SANTOS LINS
DATE: 28/01/2022
TIME: 14:00
LOCAL: Videoconferência
TITLE:

Evaluation of the influence of the synthesis parameters of ZnAl double lamellar hydroxides for application as adsorbents in water treatment

KEY WORDS:

Lamellar double hydroxide, adsorbent, experimental design and dye 

PAGES: 73
BIG AREA: Engenharias
AREA: Engenharia Química
SUMMARY:

Studies on the use of different materials as adsorbent agents have been growing more and more, especially with regard to effluent treatment. Double Lamellar Hydroxides (HDLs), also known as anionic clays, consist of stacking layers of mixed hydroxides of tri and divalent cations where the hydrated anions occupy or spaces between the layers. These materials have been standing out due to the myriad of products that can be produced varying factors such as chemical composition, reaction parameters, reactor layout, among others. In this work, an experimental design 23 was carried out, with triplicate at the central point, for the production of HDLs composed of ZnAL. The reaction factors were evaluated: pH, time and temperature, 11 materials were produced in total by the co-precipitation method at increasing pH, in order to evaluate the influence of the evaluated factors in the adsorption process of the dyes Verde Malachite and Rhodamine B, using the removal percentage as a planning response. The synthesized materials were characterized by PCZ, DRX, TG/DTG and SEM techniques, confirming the production of ZnAl and providing the main differences in the synthesized products. Later, these HDLs were used in adsorption tests carried out in a finite bath in order to remove the aforementioned dyes from aqueous solutions. For Malachite Green, the linear model states that the main effects pH and time, as well as all the second-order interaction effects were significant, however performing one of the F tests, it was found that the model shows signs of lack of adjustment. The quadratic model was tested, after performing the F test, it was observed that the generated equation is not statistically significant, being necessary to repeat one of the points studied to validate the model or redo the planning. Among the materials synthesized in the 11 syntheses, material 6 (T60pH12t6) stood out in the adsorption of the Green Malachite dye, with a removal capacity greater than 87%, the kinetic study states that the system presents a very satisfactory result in 240 minutes and the experimental data are better fitted by the pseudo-second order model, the isotherms are better represented by the Sips model, presenting a value of maximum adsorption capacity at 60°C of 629.51 mg.g-1. The negative value of ΔHo suggests that the adsorption is exothermic in nature, the negative value of ΔSo indicates that the disorder of the system decreases at the adsorbent/adsorbate interface during the adsorption reaction, and the negative values of ΔGo confirm the spontaneity of the process. For the Rhodamine B dye, the linear model was tested, where all the main effects and the secondary interaction effects were significant, with the exception of the interaction between pH and temperature. It can be seen that the highest percentage of removal occurs at lower levels for all main effects, with greater influence of pH, after performing the F test, it was found that the generated equation is not statistically significant, so the model was tested quadratic, which showed no lack of adjustment. 

BANKING MEMBERS:
Presidente - 1314677 - CARMEM LUCIA DE PAIVA E SILVA ZANTA
Externo à Instituição - Guilherme Luiz Dotto - UFSM
Interno - 1121112 - JOAO INACIO SOLETTI
Interno - 1797785 - LUCAS MEILI