Synthesis of microcapsules containing different extractant agents

Area of Science:

• Environmental Chemistry
• Materials Science
• Polymer Chemistry

Background:

• Mercury is a highly toxic pollutant that bioaccumulates, posing significant human health risks.
• Effective mercury removal from water is a critical environmental research objective.
• Previous work involved microencapsulating di(2-ethylhexyl)phosphoric acid in poly(styrene-co-divinylbenzene) using toluene.

Purpose of the Study:

• To modify a previous microencapsulation recipe by replacing toluene with heptane.
• To evaluate four additional extractant agents for mercury removal: trioctylamine, trioctylmethylammonium chloride (TOMAC), tributyl phosphate, and trioctylphosphine oxide.
• To assess the mercury removal and retention capabilities of the developed microcapsules.

Main Methods:

• Suspension polymerization was employed to create microcapsules with modified recipes.
• Waste liquid pollution potential was analyzed using total organic carbon (TOC) and chemical oxygen demand (COD).
• Microcapsule characteristics (morphology, particle size, distribution) were analyzed via scanning electron microscopy (SEM) and low-angle laser light scattering (LALLS).
• Extractant loading and microencapsulation efficiency were determined by thermogravimetric analysis (TGA).
• Mercury removal capacity was quantified through equilibrium studies.

Main Results:

• Microcapsules were successfully synthesized using heptane as a diluent and various extractant agents.
• The polluting potential of the process waste liquid was characterized.
• Morphological and particle size analyses confirmed the successful formation of microcapsules.
• Thermogravimetric analysis provided data on extractant loading and encapsulation efficiency.
• Equilibrium studies indicated varying mercury removal capacities among the different microcapsule formulations.
• Microcapsules incorporating trioctylmethylammonium chloride (TOMAC) exhibited superior mercury removal and retention capabilities.

Conclusions:

• The modified microencapsulation process is effective for incorporating various extractant agents.
• Microcapsules containing trioctylmethylammonium chloride (TOMAC) are highly effective for mercury removal and retention from water.
• This research offers a promising approach for developing advanced materials for mitigating mercury pollution.