The development of an advanced biorefinery to produce cellulosic sugars and bionanomaterials

• Ano de defesa: 2023
• Autor(a) principal: Nogueira, Carlaile Fernanda de Oliveira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Altor teor de sólido; Consumo energético; Desenvolvimento de processo; Energy consumption; Enzima; Enzyme. High dry matter; Hidrofobicidade; Hydrophobicity; Process development
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/97/97131/tde-12012024-124547/

Market trends show growing interest in cellulose nanomaterials due to their low environmental impact. However, current nanocellulose isolation technologies face technoeconomic and life cycle limitations, including high-energy input. Previous research has shown that enzymatic treatments effectively reduce energy input for mechanical nanocellulose isolation. Simultaneously, there is potential to enhance the viability of cellulosic ethanol facilities by co-producing nanocelluloses as high-value products from agricultural feedstock. Here, our goal was to study the mass balance of an enzymaticmechanical process that co-produces cellulosic sugars and nanocelluloses, evaluating the technical feasibility of converting lignified and non-lignified materials and their full valorization. First, we determined a feasible 50:50 mass ratio to obtain sugars and nanocelluloses using efficient-saccharification enzyme cocktails. This ratio, derived from breakeven point in the enzyme cost equation, serves as target for converting carbohydrates in both non-lignified and lignified feedstocks studied. We investigated the co-production of nanocelluloses (CNC and CNF) and high-titer sugars from hardwood bleached kraft pulp (HBKP), varying cellulose conversion through enzymatic treatment. We demonstrated that the coproduction of nanocelluloses and concentrated sugars from HBKP was technically viable and required low energy consumption. Cellic CTec2 treatment significantly reduced the energy input for CNF isolation, achieving total sugars concentration of 61 165 g.L-1 . Cumulative energy from 5 to 23 kWh.kg-1 , resulting in energy savings of 8 80% compared to ultra-refining HBPK without pretreatment (25 kWh.kg-1 ). Optimizing CNC yield via response surface yielded in 4.4 8.7 g/100g of HBKP. For the conversion of lignified materials, a new process method was studied to pretretreat sugarcane bagasse (SCB) and sugarcane straw (SCS), obtain sodium acetate and sugars, and isolate lignin-containing nanocelluloses (LCNC and LCNF). The pretreatment involved a modified version of the Deacetylation and Mechanical Refining (DMR) process. The process met the requirement for the full valorization of biomass and was considered versatile. The pretreated materials had high fines level (83.6 87.9%) after Cellic CTec3/HTec3 treatment, hence significantly low energy input was required during ultra-refining. The total sugars concentration was 37 48 g.L-1 for SCB and 31.3 g.L-1 for SCS. Nanocelluloses were isolated similarly to previously investigated for HBKP. The LCNC yield was 5 7 g/100g of SCB and 6 g/100g of SCS. The LCNF yield was 67 72 g/100g of SCB and 72 g/100g of SCS. The isolated lignin-containing nanocelluloses showed promising surface chemistry both as suspensions and films. LCNFs had high hydrophobicity (94o to 102º), low wettability (up to 810s), and good thermostability (Tmax 334 337 oC). The LCNCs and LCNFs obtained from SCS show promising hydrophobic characteristics and may be compatible with commercial polymers.