Biochars derived from various crop straws: characterization and Cd(II) removal potential

Area of Science:

• Environmental Science
• Materials Science
• Soil Science

Background:

• Biochar is a promising material for heavy metal remediation.
• The properties of biochar, influenced by feedstock and pyrolysis temperature, affect its sorption capabilities.
• Understanding feedstock-specific characteristics is crucial for optimizing biochar application.

Purpose of the Study:

• To characterize biochars from different crop straws and wood shaving.
• To determine the sorption capacity of these biochars for cadmium (Cd(II)).
• To investigate the relationship between biochar properties and Cd(II) sorption efficiency.

Main Methods:

• Preparation of five biochar types from crop straws and wood shaving at 600 °C.
• Characterization of biochar surface area, pore volume, and surface chemistry.
• Determination of Cd(II) sorption capacity using batch experiments.
• Analysis of surface characteristics before and after sorption using SEM-EDX and FTIR.

Main Results:

• Biochar surface area and pore volume correlated inversely with biomass lignin content.
• Crop straw biochars exhibited more developed pore structures than wood biochar.
• Cd(II) sorption capacity order: corn straw > cotton straw > wheat straw > rice straw > poplar shaving.
• Corn straw biochar's high sorption attributed to cation exchange, carbonate precipitation, and oxygen-containing groups.

Conclusions:

• Crop straw biochars possess distinct heavy metal sorption capacities due to varied surface characteristics.
• Biochar's effectiveness as a heavy metal sorbent is feedstock-dependent.
• Specific evaluation of biochar sorption efficiency for target contaminants is recommended.