Recovery of Acetic Acid from the Prehydrolysis Liquor of Kraft Based Dissolving Pulp Production Process: Sodium Hydroxide Back Extraction from the Trioctylamine/Octanol System

Acetic acid is an important potential product from the prehydrolysis liquor (PHL) of the kraft based dissolving pulp production process. This study focuses on the recovery of acetic acid from an industrial PHL from an Eastern Canadian Pulp mill that contains about 1% acetic acid. Reactive extraction with tri-<i>n</i>-octylamine (TOA) using octanol as a diluent was investigated as the potential process. Subsequently, the complexed acetic acid in the organic phase (TOA–octanol) was back extracted using a sodium hydroxide solution, while the solvent (TOA–octanol) was regenerated. The recovered acetic acid concentration was increased with increasing organic to aqueous phase ratio but at the expense of decreased extraction efficiency. At the organic to aqueous phase ratio of 40 and the NaOH to acetic acid (HAc) mole ratio of 1, the acetic acid concentration reached to 15.0, 9.8, and 10.3% for MAA (1% model acetic acid), PHL (prehydrolysis liquor), and TPHL (treated prehydrolysis liquor), respectively. It was concluded that the reactive extraction using TOA–octanol, followed by sodium hydroxide back extraction, is an efficient process in recovering and concentrating acetic acid from PHL

Interactions of Lignin with Optical Brightening Agents and Their Effect on Paper Optical Properties

Optical brightening agents (OBAs) are widely used in the production of uncoated and coated paper grades to improve their optical properties. The presence of lignin in the pulp furnishes is well-known to have a significant effect on the OBA brightening efficiency, but how OBA interacts with lignin is still not well understood. In this study we used wood lignin to investigate the lignin/OBA interactions and its effect on OBA brightening. Three lignin samples isolated from spruce, pine, and aspen were used. Both di- and tetra-sulfonated OBAs were studied. It was found that the OBA addition can effectively improve the optical properties of paper, such as ISO brightness, CIE whiteness, and <i>b</i>*, but disulfonated OBA was found to be more effective at a lower dosage (less than 0.6%) than the tetra-sulfonated OBA. The addition of a small amount of lignin (0.4%) onto filter paper had negative effects on the optical properties, but the impact depends strongly on lignin structures (lignin samples from spruce, pine, and aspen), which explain the early results that mechanical pulps from different wood species respond very differently to OBA brightening. A modified Kubelka–Munk equation was used to predict and model the brightness and whiteness response of different lignin types and OBA, which can be used to provide guidance in determining the amount of OBA needed to reach specified optical property target

Robust Guar Gum/Cellulose Nanofibrils Multilayer Films with Good Barrier Properties

The pursuit of sustainable functional materials requires development of materials based on renewable resources and efficient fabrication methods. Hereby, we fabricated all-polysaccharides multilayer films using cationic guar gum (CGG) and anionic cellulose nanofibrils (i.e., TEMPO-oxidized cellulose nanofibrils, TOCNs) through a layer-by-layer casting method. This technique is based on alternate depositions of oppositely charged water-based CGG and TOCNs onto laminated films. The resultant polyelectrolyte multilayer films were transparent, ductile, and strong. More importantly, the self-standing films exhibited excellent gas (water vapor and oxygen) and oil barrier performances. Another outstanding feature of these resultant films was their resistance to various organic solvents including methanol, acetone, <i>N</i>,<i>N</i>-dimethylacetamide (DMAc) and tetrahydrofuran (THF). The proposed film fabrication process is environmentally benign, cost-effective, and easy to scale-up. The developed CGG/TOCNs multilayer films can be used as a renewable material for industrial applications such as packaging

Preparation of a Novel Formaldehyde-Free Impregnated Decorative Paper Containing MnO₂ Nanoparticles for Highly Efficient Formaldehyde Removal

The loading of catalytic manganese dioxide (MnO2) nanoparticles onto an impregnated decorative paper has been an effective method for the removal of indoor formaldehyde (HCHO) pollutants. However, its preparation can present numerous challenges, including instability in dipping emulsions and leaching. In this investigation, a novel and stable formaldehyde-free polyacrylate dipping emulsion containing MnO2 particles was prepared and then back-coated on a decorative paper. To improve the dispersion and fixation, the MnO2 was modified with silane. HCHO can undergo physical adsorption on the cellulosic fibers present in the paper, while it can also undergo chemical degradation into CO2 within the MnO2 groups. The silane not only enhanced the interfacial adhesion to a polyacrylate resin but also increased the interlayer distance, thereby creating a larger space for HCHO absorption. The impregnated decorative paper back-coated with 10 wt % of silane-modified MnO2 exhibited a removal efficiency of approximately 90% for HCHO at 20 °C. The removal rate further improved to approximately 100% when the temperature was increased to 60 °C. Moreover, it is worth noting that the release of volatile organic compounds was exceptionally minimal. Additionally, the particleboard bonded with this impregnated decorative paper exhibited an extremely low emission of HCHO, with a value that approached 0 mg·L–1. Furthermore, the bonding strength of the surface remained unaffected. Therefore, this study provides a simple and eco-friendly method for effectively removing HCHO, which can enhance indoor air quality