Pretreatment of Biomass by Selected Type-III Deep Eutectic Solvents and Evaluation of the Pretreatment Effects on Hydrothermal Carbonization

Abstract

Hydrothermal carbonization (HTC) is a novel thermochemical conversion that converts wet biomass into energy dense solid fuel. Residual moisture under subcritical conditions reacts with a lignin-cellulose-hemicellulose matrix with the major reactions being identified as dehydration and decarboxylation. Among other reaction parameters (e.g., temperature, time, pressure), biomass morphology often plays a key role in HTC. The hypothesis of this study was enhancing the porous structure of biomass without significantly affecting biopolymer composition would augment hydrothermal carbonization (HTC). To prove the hypothesis, two type-III deep eutectic solvents (DESs), namely choline chloride:urea (ChCl:Urea, 1:2 mol/mol) and methyltriphenylphosphonium bromide:ethylene glycol (MTPB:EG, 1:4 mol/mol), were studied to pretreat loblolly pine at room temperature and ambient pressure for 1 h. DES pretreatment shows swelling of the biomass, increasing the surface fiber-to-fiber gap length by 52% and 185% for ChCl:Urea and MPTB:EG pretreatments, respectively. The total pore volume remained intact (2.6 × 10–3 cm3/g), although new small pores evolved, and existing pores were abated with DES pretreatment. Hydrochars prepared from DES pretreated loblolly pine showed a high O/C and H/C ratio resulting in a significant increase of energy content (up to 42%) and a decrease of mass yield (up to 50 wt %), indicating an enhancement of HTC severity due to the alteration of surface morphology by DES. A preliminary process economics revealed that integrated DES pretreatment-HTC would increase fixed capital investment but decrease the cost of operation and manufacturing than the standalone HTC process.

Multifunctional Loblolly Pine-Derived Superactivated Hydrochar: Effect of Hydrothermal Carbonization on Hydrogen and Electron Storage with Carbon Dioxide and Dye Removal

“…Utilization of such waste biomass for fuel and material development is in dire need, and this has reflected in increasing attention of thermochemical conversions like hydrothermal carbonization (HTC). The solid product of HTC, often called hydrochar, is profoundly studied for applications such as fuel [ 3 , 4 , 5 , 6 , 7 , 8 ], dye and heavy metal removal [ 9 , 10 , 11 ]. When it comes to adsorption or storage, the lack of porosity of hydrochar is often deemed as a bottleneck.…”

Elucidating dechlorination of waste polyvinyl chloride under high‐temperature catalytic hydrothermal treatment

“…The gaseous byproducts were vented in a fume hood and the solid and liquid phases were recovered through vacuum filtration. The solid conversion was calculated using the following equation 28…”

“…The TGA analysis was performed based on ASTM D5142. 28,34 The amount of ash were determined based on the ASTM D1102 method 28 with the use of a muffle furnace. The ash samples were also used to estimate slagging and fouling indices.…”

Technoeconomic assessment comparison of batch and continuous hydrothermal carbonization of waste corn stover into advanced biorefinery feedstock

“…Researchers have identified that, in comparison with gasification or pyrolysis, hydrothermal carbonization (HTC) is an energy‐ and cost‐effective thermochemical technology, which neither requires pre‐drying nor pre‐treatment of the biomass; 17,18 however, some studies suggest that pretreatment (acid pretreatment, alkali pretreatment, deep eutectic solvent pretreatment, etc.) can improve the HTC performance 19,20 . Hydrothermal carbonization takes place in hot, compressed water and induces wet carbonization of the waste products, for example, biomass, plastics, dairy manure, or sewage sludge to synthesize energy‐dense biorefinery feedstock 17,21,22 .…”

“…can improve the HTC performance. 19,20 Hydrothermal carbonization takes place in hot, compressed water and induces wet carbonization of the waste products, for example, biomass, plastics, dairy manure, or sewage sludge to synthesize energy-dense biorefinery feedstock. 17,21,22 Despite important literature on the HTC technology, 13,[23][24][25][26][27][28][29][30][31] few studies have been carried out on its operational economic feasibility.…”