Upgrading old corrugated cardboard (OCC) to dissolving pulp [Erratum: July 2022, v.29(11); p.6461]
2016
Jahan, M Sarwar | Rahman, M Mostafizur | Sarkar, Akash Mamon
Delignification and pentosan dissolution of old corrugated cardboard (OCC) pulp was carried out using formic acid (FA) followed by alkaline extraction at atmospheric pressure. The kappa number of the initial OCC pulp was 41.4, which was decreased to 18.0 after 3.5 h of formic acid treatment. At this point, the pentosan content in the formic-acid-treated pulp was 6.20 %, being further decreased to 3.92 % after alkaline extraction with 8 % NaOH for 120 min at 90 °C. The overall pulp yield after FA treatment and alkaline extraction reached 48.0 %. Alkaline-extracted pulp was bleached to 85 % brightness using a D₀EₚD₁EₚD₂ bleaching sequence, with α-cellulose content of 94.7 %. FA and alkaline extraction liquor dissolved mostly hemicellulose and lignin, which were isolated and characterized. The fractions of lignin and hemicellulosic sugars recovered from the FA spent liquor were 4.3 and 12.7 %, respectively. The lignin was characterized as having a lower amount of methoxyl but higher amount of phenolic hydroxyl groups.
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