Effects of Pyrolysis Temperatures and Modified Methods on Rice Husk-Derived Biochar Characteristics and Heavy Metal...

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Heavy metal contamination in water poses significant environmental and health risks.
• Biochar derived from agricultural waste offers a sustainable adsorbent material.
• Optimizing biochar properties is crucial for efficient heavy metal removal.

Purpose of the Study:

• To investigate the effect of pyrolysis temperature and chemical modification on rice husk biochar properties.
• To evaluate the adsorption capacity of modified biochar for cadmium (Cd(II)) and lead (Pb(II)) removal.
• To determine the optimal modification strategy for enhancing heavy metal adsorption.

Main Methods:

• Rice husk biochar was prepared at pyrolysis temperatures of 300, 400, and 500 °C.
• Biochar was modified using nitric acid (HNO3) and potassium hydroxide (KOH).
• Physicochemical properties and heavy metal adsorption capacities (Cd(II), Pb(II)) were characterized.

Main Results:

• Increasing pyrolysis temperature enhanced biochar's specific surface area and pore volume.
• HNO3 and KOH modifications significantly altered surface functional groups and improved adsorption.
• KOH-modified biochar (KOH-BC300) showed the highest adsorption capacities: 72.14 mg·g−1 for Cd(II) and 170.84 mg·g−1 for Pb(II).

Conclusions:

• KOH modification is more effective than HNO3 modification for enhancing heavy metal adsorption onto rice husk biochar.
• Oxygen-containing functional groups play a more critical role than specific surface area in improving adsorption performance.
• KOH-modified rice husk biochar is a promising sorbent for wastewater treatment and heavy metal remediation.