Advancing hydrothermal carbonization: Assessing hydrochar's role and challenges in carbon sequestration

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Growing need for atmospheric CO2 reduction drives research into carbon sequestration.
• Hydrochar (HC), derived from hydrothermal carbonization (HTC), is a promising carbon-rich material.
• HC's properties and applications differ significantly from pyrolytic biochar (BC).

Purpose of the Study:

• Critically evaluate hydrochar's carbon sequestration capacity and mechanisms.
• Identify factors influencing HC performance and long-term stability.
• Explore strategies to enhance HC's effectiveness as a carbon sink.

Main Methods:

• Systematic examination of key parameters: feedstock composition, reaction temperature, pH, and residence time.
• Analysis of indicators for long-term sequestration: thermal stability, chemical resilience, aromaticity, and dissolved organic carbon (DOC) leaching.
• Review of innovative improvement strategies: HTC liquid recycling, chemical modification, and salinity control.

Main Results:

• Lignin content positively impacts HC stability and thermal resilience.
• Mineral embedding (carbon-ash recalcitrance) enhances carbon stability.
• Key parameters significantly influence HC's structural integrity and carbon sequestration potential.

Conclusions:

• Hydrochar demonstrates significant potential for long-term carbon storage and climate change mitigation.
• Understanding influencing factors and optimizing production are crucial for effective HC application.
• Further research into advanced strategies can enhance HC's role as a sustainable carbon sink.