Tetrahydrofurfuryl Alcohol (THFA) Pulping of Rice Straw

Abstract

A 80-95% solution of tetrahydrofurfuryl alcohol (THFA) added with 0.15-0.5% catalytic hydrochloric acid (HCl) was used to pulp rice straw. The pulping conditions applied for organosolv digestions of the straw at atmospheric pressure and 120 • C cooking for 4 h. The characteristics of the digestion, chemical properties of the resulting pulp, and the handsheet physical properties were evaluated. As for the pulp yields, the method has high delignification specificity, at kappa number 20, the yield was ca. 60%, about 15-20% higher than the traditional alkaline pulping method. Furthermore, with increasing THFA concentrations, efficacies of delignification also increased. Increasing the catalyst dosage also caused an increase in delignification. Delignification rate of 120 • C cooking are not so appreciable, but high yield were retained. If cooking temperatures were increased to 130 and 150 • C, although even higher delignification rates were achievable, the yield decreased as well. During the cooking the dissolution of carbohydrate was low, at most 23%, consisting of mostly hemicelluloses, which was as high as 78% of the dissolved carbohydrates. The optimal conditions of the THFA/HCl cooking applied 95% THFA, 0.50% HCl, temperature of 120 • C, and cooking time of 240 min. Residue lignin in the resulting pulp was low, and can be bleached to high brightness easily with a conventional bleaching sequence. If, however, energy and operation efficiency was a primary consideration, then a procedural heating scheme could be employed. The physical properties of the THFA pulp handsheets were inferior to those of the kraft pulp. The main reason was the damage to cellulose sustained during the acidic cooking condition.

Delignification Kinetics Study on the Tetrahydrofurfuryl Alcohol/HCl Pulping of Rice Straw

“…These prior studies involved softwoods and hardwoods. As per its application to agricultural waste materials, only our previous paper studied the THFA pulping of rice straw catalyzed by adding HCl. This method showed a high delignification efficiency resulting in a relatively high pulp yield.…”

Chemical and Biological Delignification of Biomass: A Review

“…Burkart and Quigley extracted lignin with triethylene glycol and 0.5 wt % to 1.0 wt % of arylsulfonic acids (phenolsulfonic or paratoluensulfonic acid) from 392 to 433 K. ,, Ho et al pulped rice straw with 80 vol % to 95 vol % solution of tetrahydrofurfuryl alcohol (THFA) with 0.15 vol % to 0.5 vol % of hydrochloric acid. They recovered about 60 wt % of lignin with a Kappa number equal to 17 . A concentrated aqueous solution of acetic, formic, and propionic acid promoted the cleavage of β-O-4′ linkages.…”

Alternative initiatives for non‐wood chemical pulping and integration with the biorefinery concept: A review

“…Rice straw pulping by tetrahydrofurfuryl alcohol (THFA) with HCl catalyst was carried out at atmospheric pressure. 53 As for pulp yields, the method has high delignification specificity. At kappa number 20, the yield was ca.…”