A Mechanism Study on Hydrothermal Carbonization of Waste Textile

Abstract

In this work, waste textile (WT) was employed as one representative pseudo-component of municipal solid waste (MSW) to investigate the mechanisms during hydrothermal carbonization (HTC) process. The experiments were examined at 230 and 280 °C with the residence time from 30 min to 90 min. The chemical component analysis showed that a significant fraction of fixed carbon was retained within the hydrochar, while ∼98% volatile matter was detected in the soluble fraction. Our results clearly demonstrate that decarboxylation was the most important defunctionalization process, whereas dehydration turned out to be less important. The combustibility index (S) and the combustion stability index (R w ) of the hydrochar were both greater than those of WT, suggesting hydrochar was superior in combustion performance. Fourier transform infrared (FTIR) analysis and solid-state 13 C nuclear magnetic resonance (NMR) characterization displayed that large amount of aliphatic compounds decomposed, while enhancements of aromatic and carbonyl types carbons were observed in hydrochar and soluble. Higher temperature enhanced the breakage of unreacted feedstock to fragment and enforced the aromatization and repolymerization reactions to form the solid char and liquid phase. Between char and liquid phase, recombined, polycondensation and repolymerization reactions progressively occupied the dominant effects. These reactions promoted char and oil-range molecules to form hydrochar. On the basis of these outcomes, a conversion pathway of hydrothermal carbonization of WT was proposed.

Effect of the Amount of Sludge on Physicochemical Properties and Chemical Structure of Low‐rank Coal under Hydrothermal Conditions

“…Although the addition of sludge reduces the fuel characteristics and increases the aliphaticity of solid products, more hydrogen bonds in sludge are introduced and cross‐linked with benzene or phenoxy to produce the medium molecule by electrophilic substitution. These medium molecules may be undergoing recombination, polycondensation, and repolymerization reaction to prevent the decline of fuel characteristic of hydro‐char …”

Utilization of soybean dregs for solid fuel production through hydrothermal carbonization

“…According to Figure 6, the hydrochar with the highest carbon content was produced at temperature of 220°C and at a holding time of 60 minutes, which was 26.49%. The carbon content of the hydrochar increases as the temperature increases, indicating that higher temperature increases the decomposition of biomass which does not react to become fragments and promote aromatization and re-polymerization reactions to produce hydrochar [11]. Also, an increase in the temperature reduces its volatile matter while increasing the carbon content and calorific value, since both processes are influenced by hydrolysis reaction [17].…”

“…This is a thermochemical process which converts waste at a high temperature and pressure, usually in a vacuum condition, into energy [6,10]. Water is used as a solvent as well as a catalyst in the process [11] and this increases the hydrolysis reaction during the HTC process, thereby making the wet biomass need no pre-drying before being used in the process [12]. The main product from the HTC process is known as hydrochar.…”

Preparation of Solid Fuel Hydrochar over Hydrothermal Carbonization of Red Jujube Branch

“…Compared with the biomass treatment technology of pyrolysis and combustion, HTC has the advantages of low energy input and mild reaction conditions [7]. Therefore, HTC is a good approach to convert biomass feedstocks to upgraded solid products or high-performance fuels.…”