Preparation of some starch-based neutral chelating agents

Area of Science:

• Materials Science
• Environmental Chemistry
• Polymer Chemistry

Background:

• Maize starch is a renewable resource with potential applications in environmental remediation.
• Developing efficient methods for heavy metal removal from aqueous solutions is crucial for environmental protection.

Purpose of the Study:

• To synthesize novel neutral starch derivatives using urea, thiourea, and melamine-based resins.
• To investigate the factors influencing the synthesis of these starch derivatives.
• To evaluate the efficacy of these derivatives in removing heavy metals from solutions.

Main Methods:

• Maize starch was reacted with mono- and dimethylol resins (urea, thiourea, melamine).
• Reaction parameters such as curing duration, catalyst, and resin concentrations were optimized.
• The synthesized starch derivatives were tested for their sorption ability towards heavy metal ions.

Main Results:

• Starch derivatives exhibited varying sorption abilities based on resin type and metal ions.
• Sorption followed the order: monomethylol > dimethylol resin-starch and thiourea > urea > melamine resin-starch.
• Sorption efficiency correlated with nitrogen content, increasing to a maximum then decreasing.
• Mercury ion (Hg2+) sorption values (mmol/mol resin) at maximum efficiency were 1135 (urea), 2624 (thiourea), and 2538 (melamine).

Conclusions:

• Starch-based resins, particularly thiourea derivatives, are effective for heavy metal removal.
• Ligand behavior varied, with urea acting as bidentate and thiourea/melamine as tridentate ligands.
• These findings suggest potential for developing sustainable adsorbents for wastewater treatment.