Modelling of palladium(II) adsorption onto amine-functionalised zeolite using a generalised surface complexation...

Area of Science:

• Environmental Chemistry
• Materials Science
• Chemical Engineering

Background:

• Palladium is a vital precious metal used in medicine, catalysts, and industry.
• Industrial processes using palladium often generate wastewater with elevated palladium concentrations, posing environmental risks.
• Effective methods for palladium recovery from industrial effluents are crucial for resource conservation and pollution control.

Purpose of the Study:

• To investigate the recovery of palladium from aqueous solutions using zeolite functionalized with spent brewer's yeast.
• To develop and calibrate a geochemical model for predicting palladium sorption processes.
• To assess the efficiency of the adsorbent under various conditions and validate the predictive model.

Main Methods:

• Batch experiments were conducted to study palladium recovery.
• A generalized surface complexation model was calibrated using parameter estimation (PEST) coupled with the PHREEQC geochemical modeling code.
• Sorption constants were determined for palladium reactions with the functionalized zeolite, considering amine surface groups, adsorption sites, and surface area.

Main Results:

• The highest palladium recovery (>97%) was achieved at pH 2 and an adsorbent dosage of 10 g L^-1.
• Palladium recovery decreased with increasing solution pH.
• The presence of competing ions and anions enhanced the amount of palladium removed.
• Model predictions showed no significant difference from experimental data (p > 0.05).

Conclusions:

• Zeolite functionalized with brewer's yeast is an effective adsorbent for palladium recovery from aqueous solutions.
• The PHREEQC-PEST coupled model accurately predicts palladium recovery using amine-based adsorbents, even with limited data.
• This approach offers a valuable tool for predicting sorption processes on novel materials in environmental remediation.