RT info:eu-repo/semantics/doctoralThesis
T1 Valorization of Black Liquor using Hydrothermal Treatment
A1 Demirkaya, Emre
A2 Universidad de Valladolid. Escuela de Doctorado
K1 Química analítica
K1 Black Liquor
K1 Liquor de Negro
K1 Supercritical Fluids
K1 Fluidos supercriticos
K1 Hydrothermal Treatment
K1 Tratamiento hidrotermico
K1 23 Química
AB Black liquor, a by-product of pulp mills and biorefineries, has emerged as a promising candidate for these purposes. The aim of this work is to valorise black liquor using hydrothermal processing (HTL) technology to produce an end-use material (bio-lubricant) and to test various conditions to monitor the effects of HTL.The first chapter focuses on supercritical water depolymerisation of black liquor, refining and analysis of products including biopolyols. Hydrothermal treatment (HTL) of black liquor (385°C, 26 MPa) was carried out in a custom-designed supercritical water (SCW) pilot plant with rapid reaction times of about 0.4 seconds. The study used a higher concentration of black liquor (20 wt% total solids) and investigated downstream processing methods to minimise cost and time for industrial applications. This study highlights continuous operation (>1 h) and short reaction times (~0.4 s) to produce biopolyols and aromatic bio-oil from black liquor.The second chapter aims to valorise black liquor through SCW treatment to produce semi-solid bio-lubricants. Black liquor was subjected to supercritical water depolymerisation and downstream processing to obtain three fractions (spray drying, oven drying and ethyl acetate extraction). These fractions were added to epoxy-modified vegetable oils to create sustainable lubricant formulations. The bio-lubricants showed remarkable physical stability, desirable appearance, shear thinning and viscoelastic behaviour, and adequate tribological performance. Lignin samples in epoxidised castor oil showed similar shear thinning behaviour to conventional lithium soap thickened greases. The final chapter examines the depolymerisation of black liquor and kraft lignin using supercritical water, with NaOH as the catalyst for kraft lignin. This study represents the first rapid reaction screening of black liquor and precipitated kraft lignin, providing a comprehensive characterisation of all fractions. The experiments were carried out in a continuous pilot plant at TRL4 with fast reaction times (0.5, 1 and 1.5 seconds) at temperatures of 380°C and 390°C and a pressure of 26 MPa. Higher temperatures and longer reaction times during SCW treatment significantly increased phenolic compound concentrations, resulting in lower pH and lower total solids content. The SCW process achieved maximum total oil yields of 79.45 wt% for black liquor and 68.54 wt% for kraft lignin at 390°C.Overall, this research highlights the potential of black liquor and kraft lignin depolymerisation through SCW treatment to produce valuable biopolyols and biolubricants with significant environmental and industrial benefits.
YR 2024
FD 2024
LK https://uvadoc.uva.es/handle/10324/71409
UL https://uvadoc.uva.es/handle/10324/71409
LA eng
NO Escuela de Doctorado
DS UVaDOC
RD 27-nov-2024