[Phosphate Removal Using Rice Husk Biochars Modified with Lanthanum Hydroxide]

Area of Science:

• Materials Science
• Environmental Science
• Nanotechnology

Context:

• Phosphate pollution is a significant environmental concern, impacting water quality and aquatic ecosystems.
• Developing efficient and sustainable adsorbents for phosphate removal is crucial for water remediation.
• Rice husk biochar offers a low-cost, abundant, and eco-friendly precursor for adsorbent development.

Purpose:

• To fabricate and characterize lanthanum-modified rice husk biochars (La-RHBCs) for phosphate adsorption.
• To investigate the influence of biochar's pore structure, pH, and coexisting substances on phosphate adsorption efficiency.
• To evaluate the adsorption kinetics, isotherms, and selectivity of La-RHBCs for phosphate removal.

Summary:

• La-RHBCs were synthesized by immobilizing La(OH)3 nanoparticles onto mesoporous rice husk biochars (RHBCs).
• Phosphate adsorption capacity and rate were positively correlated with RHBCs' mesoporosity, leading to higher La loading and reduced La leaching.
• Adsorption followed pseudo-second-order kinetics and Langmuir isotherm models, with maximum capacities ranging from 41.22 to 45.62 mg·g−1.
• La-RHBCs demonstrated effective phosphate removal across a wide pH range (3-9) and showed good selectivity in the presence of interfering substances.

Impact:

• La-RHBCs present a highly efficient and selective adsorbent for phosphate removal from aqueous solutions.
• The study highlights the potential of utilizing agricultural waste (rice husks) for environmental remediation.
• The findings contribute to the development of sustainable technologies for managing phosphorus pollution.