Uranium capture from aqueous solution using palm-waste based activated carbon: sorption kinetics and equilibrium

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Radioactive effluent poses significant environmental and health risks.
• Agricultural waste, such as palm kernel shell, is abundant and underutilized.
• Development of cost-effective adsorbents is crucial for radioactive waste treatment.

Purpose of the Study:

• To investigate the efficacy of bio-char derived from palm kernel shell and its activated forms as adsorbents for uranium removal from aqueous solutions.
• To characterize the adsorbents using various analytical techniques.
• To evaluate the sorption kinetics, isotherms, and thermodynamics of uranium removal.

Main Methods:

• Pyrolysis of palm kernel shell to produce bio-char (PBC).
• Activation of bio-char using sulfuric acid (PBC-SA) and zinc oxide (PBC-Zn).
• Characterization using SEM, EXD, BET, FTIR, and Zeta potential.
• Sorption experiments to determine kinetics, isotherms, and thermodynamics.
• Desorption and stability tests.

Main Results:

• The sorption process followed Pseudo-second-order kinetics and Langmuir isotherm models.
• Maximum sorption capacities were 9.89 mg/g (PBC), 16.8 mg/g (PBC-SA), and 21.9 mg/g (PBC-Zn).
• PBC-Zn exhibited the highest affinity for uranium removal.
• Uranium sorption was an exothermic, spontaneous, and feasible process.
• 92% uranium elution was achieved with sodium acetate, and the PBC-Zn sorbent showed good stability over 5 cycles.

Conclusions:

• Palm kernel shell-derived bio-char and its activated forms are effective low-cost adsorbents for uranium removal.
• Zinc oxide activated bio-char demonstrates superior performance for uranium remediation from radioactive wastewater.
• The developed adsorbents offer a sustainable solution for treating radioactive effluents, with potential for regeneration and reuse.