Amine-grafted walnut shell for efficient removal of phosphate and nitrate

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Emerging pollutants like phosphate (PO4^3-) and nitrate (NO3-) pose significant risks to water bodies and human health.
• Effective treatment of industrial effluents is crucial for environmental safety and public health.

Purpose of the Study:

• To synthesize and characterize amine functionalized walnut shells (ACWNS) as a novel adsorbent.
• To investigate the efficiency of ACWNS for the removal of phosphate and nitrate from aqueous solutions.

Main Methods:

• ACWNS were synthesized and characterized.
• Adsorption experiments were conducted to evaluate the effects of pH, dosage, initial concentration, interference ions, and temperature.
• Adsorption kinetics and isotherms were analyzed using pseudo-second-order, Freundlich, and Langmuir models.

Main Results:

• ACWNS demonstrated significant adsorption capacity for both phosphate (82.2 mg g^-1) and nitrate (35.7 mg g^-1) at 293 K.
• Adsorption was found to be exothermic and spontaneous, driven by electrostatic interactions and hydrogen bonding.
• The pseudo-second-order kinetic model best described the adsorption process, while Freundlich and Langmuir models fitted phosphate and nitrate adsorption, respectively.

Conclusions:

• ACWNS is a highly efficient and promising adsorbent for the simultaneous removal of phosphate and nitrate from water.
• The material's effectiveness was confirmed in real water samples, indicating its potential for practical remediation applications.