MEA/water/AQ-pulping of wheat straw

Abstract

Annual plant pulping is faced with serious challenges. Traditional pulping processes with bleaching in chlorine based sequences and without appropriate chemical recovery system cannot be tolerated anymore. Alternative pulping processes with non-conventional chemicals, such as organic solvents, e.g., monoethanolamine (MEA), might be suited for an environmentally sound process with a closed mill system. Thus, pulping of wheat straw with MEA as the main delignifying agent was investigated in comparison to soda and soda/AQ pulps as references. The main focus was placed on reduction of the cooking temperature in order to avoid heat-induced MEA degradation. The temperature was reduced stepwise from 165°C to 130°C. At 150°C, a sufficient delignification was achieved. MEA was partly substituted by water and the resulting decrease of the delignification rate could be compensated by addition of anthraquinone (AQ). After optimization of the process, a pulp with a kappa number of 17 was obtained at a total yield of 56% based on o.d. straw. This pulp was selected for bleaching. Both, O/Q/OP/DQ/P (“ECF light”) and O/Q/OP/ZQ/P (TCFZ) bleaching were applied. NaOH was substituted by MEA as alkali source in the oxygen delignification stage. Up to 50% delignification rate was achieved under these moderate conditions. In the ECF light bleaching sequence, a brightness of 80% ISO was reached at a kappa number level below 3. In TCFZ bleaching, an even somewhat higher brightness was achieved at a kappa number level below 1. A yield of fully bleached screened pulp of around 50% (based on o.d. straw) was obtained. The strength properties of the MEA pulp were improved after bleaching. ECF bleaching resulted in slightly better pulp strengths than the TCFZ alternative. MEA forms in combination with water and AQ a very selective pulping system providing effective delignification and maintaining extremely high yields. MEA/water/AQ pulping should be regarded as a serious, environmentally friendly alternative to soda or soda/AQ pulping to produce high-quality pulp from wheat straw.

Investigation on physical and mechanical properties of pulp–plastic composites from bagasse

“…The extent of delignification depends on the lignin structure as well as on the adjusted Na 2 SO 3 to NaOH ratio. MEA pulping process is an organosolv pulping process which has appropriate performance on lignocellulosic non-wood natural fibers (Hedjazi et al 2009). The most important advantage of MEA pulping of annual plants is the direct MEA recovery by distillation.…”

“…Green and Sanyer (1982) presumed that carbohydrates in the presence of MEA are stabilized against peeling reactions by reduction of reducing end groups. Compared to the SODA pulping, MEA pulping gives 12% higher yield (Hedjazi et al 2009). The chemicalmechanical pulping (CMP) process has the advantages of a mild chemical treatment with cooking liquor consisting of a mixture of Na 2 SO 3 and NaOH and of high pulping yield compared with the chemical pulping process.…”

Environmental Friendly Pulping of Kenaf Using Monoethanolamine: Influence of the Process Variables on the Strength Properties

“…The most widely researched organosolv processes use alcohols, organic acids, acetone, phenol, formaldehyde, ethanolamine, or ethylene glycol; the latter two possess a high boiling point and can thus be used at pressure levels similar to those of classical processes. 1,5 Kenaf, a word of Persian origin that is used to describe the plant, Hibiscus cannabinus L. is a warm season, short-day, annual herbaceous plant, which originated in West Africa. Kenaf grows quickly, rising to a height of 3.7-5.5 m, in as little as 4-5 months in suitable temperature, soil, and rainfall conditions.…”

“…This has led to intensive investigation by many research groups. The most widely researched organosolv processes use alcohols, organic acids, acetone, phenol, formaldehyde, ethanolamine, or ethylene glycol; the latter two possess a high boiling point and can thus be used at pressure levels similar to those of classical processes …”

Multivariate-parameter optimization of the alkaline peroxide mechanical pulp (APMP) process for larch (Larix gmelinii Rupr.) using Box-Behnken design

“…This research area has numerous variations concerning the raw materials (including annual plants, hardwoods, softwoods), aspects of chemistry and refining (pulping chemicals, pretreatments, refiners), and analysis as revealed in the recent literature (Hedjazi et al 2008(Hedjazi et al , 2009Iakovlev et al 2009;Vicentim et al 2009;Al-Dajani and Tschirner 2010;Liu et al 2010;Hörhammer et al 2011;Yamamoto et al 2011;Zhang et al 2011a;Hafrén et al 2012). Many of them are based on the bleached chemo-thermomechanical pulping (BCTMP), alkaline peroxide mechanical pulping (APMP), and preconditioning refiner APMP of hardwood.…”