Banca de QUALIFICAÇÃO: IZAIAS CAMPOS DA PAIXÃO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : IZAIAS CAMPOS DA PAIXÃO
DATE: 20/11/2023
TIME: 09:00
LOCAL: videoconferência
TITLE:

Electrorefinery of lignin for the production of green hydrogen and high-value-added carboxylic acids.

KEY WORDS:

Electrorefinery; Biomass; anodic oxidation; cyclical economy 

PAGES: 100
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:

With the growing concern for environmental issues, there is a pursuit of optimizing effluent remediation technologies, the production of renewable and green fuels, and the production of environmentally sustainable inputs for the chemical industry. The use of electrochemical reactions to facilitate effluent degradation is an alternative that can be coupled with the use of renewable energies such as photovoltaic and wind, thereby reducing execution costs. These anodic oxidation technologies enable the electro-degradation of contaminants into industrially relevant carboxylic acids (electro-refining) and the production of green hydrogen at the cathode. The treated effluent was lignin, a natural polymer found in plant biomass and widely discarded as agricultural waste. An electrochemical system was developed in a flow reactor using a non-active boron-doped diamond (BDD) electrode and stainless steel as the anode and cathode, respectively, with varying electrolyte concentrations of NaOH (0.5; 1,0 e 2,0 mol L^-1) and current densities (40, 70, and 120 mA cm^-2). The results are presented in the first article (Sustainable electrochemical process for reforming lignocellulosic biomass in high value-added products: green hydrogen, carboxylic acids and vanillic acid). Subsequently, the anionic electrode was replaced with a dimensionally stable anode (DSA), and experiments were conducted under the same previously mentioned conditions. Following this, the separation of the acids produced was evaluated using an electrodialysis system with both BDD and DSA electrodes, varying only the current densities (40, 70, and 120 mA cm^-2), and an electrolyte concentration of 0.5mol L^-1 NaOH (the results will be presented in a second article). During the experiments, total organic carbon (TOC), chemical oxygen demand (COD), and carboxylic acids were evaluated and quantified using ion chromatography and high-performance liquid chromatography (HPLC). The production of acetic, formic, vanillic, and oxalic acids was observed, with oxalic acid being the predominant one, reaching concentrations of 80 mg/L (under conditions of 0.5 mol L^-1 NaOH and 100 mA cm^-2). The best concentrations of vanillic acid reached 0.6 mg L^-1, simultaneously with the production of over 2.6 liters of H₂ in the cathodic compartment. A renewable energy source, photovoltaics, was used to minimize energy costs. Preliminary results indicate that lignin electro-refining is a viable alternative for the production of green H₂ and carboxylic acids.

COMMITTEE MEMBERS:
Interna - 2140818 - AMANDA DUARTE GONDIM
Presidente - 1645110 - CARLOS ALBERTO MARTINEZ HUITLE
Externo à Instituição - JOÃO MILLER DE MELO HENRIQUE - IFSERTAO
Externa ao Programa - ***.673.134-** - JUSSARA CÂMARA CARDOZO - UFRN