Removal of toxic elements from aqueous solution using bentonite modified with L-histidine

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Acidic drainage from mining activities contaminates water sources with toxic heavy metals.
• Conventional water treatment methods can be costly and less effective for certain metal ions.

Purpose of the Study:

• To investigate the efficacy of bentonite modified with L-histidine for removing various heavy metals from aqueous solutions.
• To optimize adsorption conditions and understand the adsorption mechanism for heavy metal removal.

Main Methods:

• Bentonite was modified with L-histidine, and its surface area and elemental composition were analyzed.
• Batch adsorption experiments were conducted to study the effects of pH, initial concentration, contact time, and temperature.
• Adsorption data were fitted to Langmuir and Freundlich isotherm models, and kinetic studies followed pseudo-second-order models.

Main Results:

• Bentonite-histidine exhibited efficient removal of Cu, Co, Cr, Fe, Hg, Ni, U, and Zn.
• The Freundlich isotherm model best described the adsorption of Cu, Co, Ni, and Zn, indicating heterogeneous surface adsorption.
• Adsorption kinetics followed a pseudo-second-order model, and thermodynamic analysis revealed spontaneous, endothermic adsorption.

Conclusions:

• Bentonite modified with L-histidine is a promising adsorbent for heavy metal removal, especially from acidic environments like acid mine drainage.
• The adsorption process is chemically controlled and effective at low pH values.
• This modified bentonite offers a viable solution for water remediation contaminated with toxic metals.