Optimization of Ni (II) biosorption from aqueous solution on modified lemon peel

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Agricultural waste valorization offers sustainable solutions for water treatment.
• Nickel (II) contamination in aqueous effluents poses environmental and health risks.
• Developing cost-effective biosorbents is crucial for efficient heavy metal removal.

Purpose of the Study:

• To investigate the potential of lemon peel as a biosorbent for Ni (II) removal.
• To optimize chemical modification methods for enhancing lemon peel's adsorption capacity.
• To evaluate the adsorption mechanism, kinetics, thermodynamics, and reusability of the modified biosorbent.

Main Methods:

• Chemical modification of lemon peel using various agents (HNO3, HCl, H3PO4, CaCl2, NH3, NaOH).
• Adsorption experiments to determine optimal conditions (pH, sorbent dosage, temperature).
• Langmuir model for maximum adsorption capacity, pseudo-first-order model for kinetics, and thermodynamic analysis.
• Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) for characterization.
• Adsorption-desorption cycles to assess reusability.

Main Results:

• NaOH modification significantly improved lemon peel's adsorption capacity.
• Maximum adsorption capacity reached 36.74 mg/g under optimal conditions (pH 5, 5 g/L, 25°C).
• Biosorption followed pseudo-first-order kinetics and was endothermic and spontaneous.
• Recovered 90% of Ni (II) after five adsorption-desorption cycles using 0.1 M HNO3 and H2SO4.

Conclusions:

• Modified lemon peel is a highly effective and reusable biosorbent for Ni (II) removal from aqueous solutions.
• This approach offers a sustainable and economical method for treating heavy metal-contaminated wastewater.
• Surface functional groups and morphology changes contribute to enhanced Ni (II) adsorption.