Banca de DEFESA: ANDRÉ RICARDO CALCIOLARI

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANDRÉ RICARDO CALCIOLARI
DATE: 27/06/2022
TIME: 19:30
LOCAL: Plataforma Microsoft TEAMS
TITLE:

EVALUATION OF BIOCHAR PREPARATION FROM SILVER COFFEE SKIN PYROLYSIS AND ITS VIABILITY IN THE REMOVAL OF Pb2+ IONS FROM AQUEOUS SOLUTION

KEY WORDS:

 Response Surface Methodology; Biochar; Adsorption; Heavy metals; Pyrolysis.

PAGES: 179
BIG AREA: Engenharias
AREA: Engenharia de Minas
SUMMARY:

The mineral sector stands out as one of the industrial activities that most impact the environment. In this sense, it has contributed to the generation of a large of tailings and solid wastes that can contain a wide range of toxic metals. Added to this is the generation of waste of another nature from agricultural activities that also impact the environment when discarded without any treatment. From this perspective, biochar has been investigated as a promising alternative to improve water and soil quality. Its adsorptive properties can be enhanced by optimizing of its production conditions and/or by physical or chemical activation. However, although activation has several advantages, it almost always results in high cost and secondary waste generation. This work aimed to evaluate the potential of coffee silverskin biochar (BC) in the removal of the Pb2+ ions from in aqueous solution. The BC was prepared in a low-oxygen muffle furnace at five temperature levels (338 °C, 400 °C, 550 °C, 700 °C, and 768 °C) and residence times (95, 120, 180, 240, and 265 min) with a heating rate of 10 °C/min. The experimental design is based on the central composite design 22, with 5 repetitions in the center. The experimental design was applied to investigate the effects of temperature and residence time variables on methylene blue (MB) adsorption capacity and BC yield. Studies of kinetics and equilibrium of adsorption of MB were also carried out to verify the adsorbent potential of the material. The BC with the best adsorption performance was selected and evaluated egarding its ability to remove Pb2+ ions from aqueous solutions. This BC was subjected to additional characterizations regarding its specific surface area (N2 adsorption), surface functional groups (FTIR), elemental analysis (CHNS-O), surface charge (Zero point charge - ZPC), thermal stability (TG/DTG), chemical structure and crystallinity (Raman Spectroscopy/XRD). The results obtained from the response surface methodology (RSM) revealed that the pyrolysis temperature exerted significant effects on the adsorption capacity and yield of BC. The combination of parameters that came closest to the optimal conditions determined by the RSM was regarding the BC prepared at 400 °C and 120 min (BC1). The kinetic and equilibrium
data were better fitted by the Elovich (R2(aj.) = 0.998; χ2 = 5.495) and Langmuir (R2(aj.) = 0.952; 2χ = 106.714) models, respectively, suggesting that chemisorption was the dominant mechanism and that the adsorption occurred in monolayer. The theoretical maximum adsorption capacity (Qmax), for BC1, of 160.08 mg/g and the value of the separation factor (RL), between 0.58 and 0.03; indicate that the adsorption of MB by BC1 was favorable. The amount of lead remaining was quantified by the microwave induced plasma optical emission spectrometry (MIP-OES) technique. The BC1 showed an efficiency of 93.0% in the removal of Pb2+ ions from the aforementioned solution. Additional tests showed that the BC7 sample, pyrolyzed at 550 °C for 95 min, removed up to 96.6% of Pb2+ ions from the same solution, showing an excellent fit and reliability of the results. Therefore, PPC BCs can be considered promising adsorbents for the decontamination of lead ions present in an aqueous solution and can be a sustainable and more affordable alternative when compared to activated carbon.

BANKING MEMBERS:
Presidente - MARIO GUIMARAES JUNIOR
Interna - MICHELLY DOS SANTOS OLIVEIRA
Externo à Instituição - JOÃO RODRIGO COIMBRA NOBRE - UEPA
Externa à Instituição - CORDÉLIA ALVES RIOS