Polyethyleneimine Addition for Control of Dissolved and Colloidal Substances: Effects on Wet-End Chemistry

Abstract

Within the pulp and paper industry, the recycling of whitewater to reduce fresh water consumption and effluent volume leads to an accumulation of dissolved and colloidal substances (DCS) in the papermaking wet-end system. DCS interacts with certain electrolytes and polyelectrolytes to form non-ionic DCS interferents (pitch deposits and depositions), which adversely affect papermaking. Polyethyleneimine (PEI), a fixing agent with a low molecular weight and high cationic charge density, can control the DCS in the wet-end system. The fixation efficiency of DCS simulacra and the wet-end properties were explored under varying Ca 2+ and PEI concentrations in pulp. The fixation and retention efficiency of DCS simulacra were improved, the zeta potential of pulp and drainage rate of pulp increased, and the cationic demand of pulp filtrate decreased with increasing PEI dosage. Ca 2+ shielded the negatively charged ions on the surface of the fibers and DCS simulacra, influenced the fixation efficiency of PEI to DCS simulacra, and improved the drainage rate of pulp.

Aggregation Process and Mechanism of Pitch Deposits with Ca2+ in Papermaking White Water

“…This increased the characteristic size of the suspended matter to the range of about 0.2 to 5 m, such that the scattering of light was high, giving an increase of the turbidity. The higher the Ca 2+ concentration, the more pitch deposits and higher turbidity there will be (Wang et al 2016). The change of turbidity tended to be gentle after a complete reaction of CS simulacra and Ca 2+ .…”

Tailoring cellulose nanocrystals rheological behavior in aqueous suspensions through surface functionalization with polyethyleneimine

“…Given the advantages of CNCs obtained from sulfuric acid treatment, namely, their availability at a commercial scale, good dispersion in water, and possibility of non-covalent modification, we decided to investigate the surface modification of these particles in an aqueous medium using a suitable cationic additive and study the rheological properties of the resulting aqueous suspensions. Polyethyleneimine (PEI) was chosen as the cationic polymer for this non-covalent surface modification as it is water soluble, is commercially available in both linear and branched forms, and has been reported for numerous applications such as a low toxicity cross-linker (Reddy et al, 2003;Jia et al, 2010;and Sun et al, 2011), a binding or fixing agent that improves the effluent quality of the pulp and the print quality on paper in the pulp and paper industry (Wang et al, 2016), for drug delivery and other biomedical applications (Lin and Dufresne, 2014), for its anti-microbial properties (Azevedo et al, 2014), and a chelation agent with heavy metals (Kobayashi et al, 1987). PEI has also been chemically bound to TEMPO-oxidized CNCs to aid their dispersion in polymers such as epoxy resins (Zhao et al, 2017) and used to crosslink cellulose nanofibrils to create biomedical scaffolds (Alexandrescu et al, 2013).…”

Cross-Linking of Oxidized Hydroxypropyl Cellulose in Paper: Influence of Molecular Weight and Polymer Distribution on Paper Wet Strength Development

“…As the third and last polyamine, we study in detail the strengthening properties in paper of keto-HPC in combination with branched polyethylene imine, which is commercially synthesized by the cationic ring-opening polymerization of aziridine, and is therefore available in bulk [ 33 ]. Note that although both chitosan and aminated lignin are of biogenic origin and thus would add a higher degree of sustainability, PEI is an already-established retention and drainage aid for paper making, and also provides good fixation effects when applied as anionic trash-fixing agent [ 34 ]. As such, it can serve as a model polyamine in an excellent manner.…”