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Removal of Pb (II) from aqueous solution by sulfur-functionalized walnut shell
1School of Civil Engineering and Architecture, East China Jiao Tong University, Nanchang, 330013, Jiangxi, China.
Environmental Science and Pollution Research International
|March 17, 2019
Summary
Modified walnut shells effectively remove lead from water. Grafting sulfur groups onto walnut shells created a low-cost biosorbent (SWM) with significantly improved lead adsorption capabilities via complexation and ion exchange.
Area of Science:
- Environmental Chemistry
- Materials Science
- Water Treatment
Background:
- Heavy metal lead contamination poses significant environmental and health risks.
- Effective and economical methods for lead removal from water are urgently needed.
- Natural materials offer potential as sustainable adsorbents for pollutant remediation.
Purpose of the Study:
- To synthesize a low-cost biosorbent from walnut shells modified with sulfur-containing functional groups for lead removal.
- To characterize the modified biosorbent and evaluate its adsorption performance for lead ions (Pb(II)).
- To investigate the adsorption mechanism, kinetics, isotherms, and thermodynamics.
Main Methods:
- Walnut shells were modified with xanthate to introduce sulfur-containing functional groups.
- Characterization techniques included FT-IR, XPS, SEM, and BET analysis.
- Batch adsorption experiments were conducted to study the effects of pH, adsorbent dosage, contact time, initial concentration, and temperature.
Main Results:
- Successful grafting of sulfur-containing functional groups onto the walnut shell was confirmed.
- The modified biosorbent (SWM) exhibited significantly enhanced Pb(II) adsorption compared to unmodified walnut shells.
- Adsorption followed the Temkin isotherm model and pseudo-second-order kinetics, indicating spontaneous and exothermic adsorption.
Conclusions:
- Sulfur-modified walnut shell (SWM) is a highly effective and low-cost biosorbent for lead removal from water.
- The enhanced adsorption is attributed to complexation by sulfur groups and ion exchange mechanisms.
- SWM shows great potential for practical application in treating lead-contaminated water.
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