Effective Removal of Selenium from Aqueous Solution using Iron-modified Dolochar: A Comprehensive Study and Machine...

Area of Science:

• Environmental Chemistry
• Materials Science
• Adsorption Science

Background:

• Selenium (Se) is an essential micronutrient but toxic in excess, posing risks to human health and ecosystems.
• Effective removal of selenium from aqueous solutions is crucial for environmental protection and water safety.

Purpose of the Study:

• To investigate the efficacy of iron-doped dolochar (FeD) as an adsorbent for selenium removal from aqueous solutions.
• To characterize FeD and understand its surface properties influencing selenium adsorption.
• To optimize adsorption parameters and evaluate the adsorption mechanism and thermodynamics.

Main Methods:

• Characterization of iron-doped dolochar (FeD) using SEM, EDX, BET, XRD, and FTIR.
• Adsorption experiments conducted by varying pH, dosage, contact time, and initial selenium concentration.
• Adsorption isotherm and kinetic studies using Langmuir and pseudo-second-order models.
• Thermodynamic analysis and investigation of competing ion effects.
• Model comparison using Gaussian Process Regression.

Main Results:

• FeD exhibited a high surface area (100 m²/g) and optimal adsorption at pH 2, with ~98% selenium removal achieved.
• Adsorption followed Langmuir isotherm (R² = 0.99) and pseudo-second-order kinetics, indicating monolayer adsorption.
• Thermodynamic studies revealed a spontaneous, endothermic adsorption process with increased randomness.
• Phosphate, sulfate, and nitrate ions showed the most significant interference in selenium adsorption.

Conclusions:

• Iron-doped dolochar (FeD) is a highly effective adsorbent for selenium removal from aqueous solutions.
• The adsorption process is well-described by Langmuir isotherms and pseudo-second-order kinetics.
• FeD presents a promising, cost-effective solution for selenium remediation with a potential ROI of 35.5%.