Nuclear chemistry

Catalysis

Engineering

Materials science

Steam explosion

Furfural

Cellulose

Hemicellulose

Inorganic chemistry

Chemical engineering

Food science

Organic chemistry

Straw

Hydrolysis

Chemistry

Xylose

Pulp and paper industry

Fermentation

Lignin

ACS Sustainable Chemistry & Engineering

This study evaluated the potential of an acid hydrotropic process at low temperatures for on-farm valorization of wheat straw by producing ligocellulosic nanofibrils (LCNFs), lignin nanoparticles (LNPs), and furfural. p-Toluenesulfonic acid (p-TsOH) was used to fractionate wheat straw under a range of conditions below 90 °C at low to moderate concentrations, between 15 and 60 wt %, for up to 2 h. p-TsOH fractionated wheat straw into a cellulose-rich water-insoluble solid (WIS) fraction and a spent liquor stream that contained dissolved lignin and xylan. Various degrees of delignification and hemicellulose dissolution were obtained and were correlated with a combined delignification factor (CDF) and a combined hydrolysis factor (CHF), respectively. A low p-TsOH concentration of 15 wt % can be used to obtain the desired degree of delignification for producing LCNFs directly from wheat straw. Films made of wheat straw LCNFs, with lignin contents of 12–22%, had excellent mechanical properties, with specific tensile strength over 120 kN·m/kg. The dissolved xylan in the spent liquor was directly dehydrated into furfural catalyzed by the p-TsOH in the spent liquor without an additional catalyst. The dissolved lignin was easily precipitated as LNPs through dilution using water. p-TsOH, as a solid catalyst, can be reused after the steps of lignin precipitation, reconcentration, and dehydration of xylose into furfural. The low-temperature fractionation process could substantially reduce capital and operating costs for on-farm applications.

Valorization of Wheat Straw Using a Recyclable Hydrotrope at Low Temperatures (≤90 °C)