Synthesis of sulphonated microcapsules of P(St-DVB) containing di(2-ethylhexyl)phosphoric acid

A new sulfonated material from styrene-divinylbenzene copolymer, P(St-DVB), containing di(2-ethylhexyl)phosphoric acid (DEHPA) that combines the advantages and capabilities of the ion exchange and the solvent extraction technologies has been developed. Microcapsules with a DEHPA content of 34.86 wt.%, an average particle size of 340.83 μm and an equivalent thickness shell of 22.4 μm were prepared by suspension-like polymerization technique and further sulfonated. The influence of the chemical nature and properties of the suspending agent on the microcapsules characteristics were studied. The polluting potential of the wastewater generated in the encapsulation process with the different suspending agents was also evaluated. Arabic gum:PVA showed to be the best combination of suspending agent for the process. The incorporation of sulfonic groups to the polymeric network turn the hydrophobic nature of the particle into another with hydrophilic character. The increase of the sulfonation time from 10 to 30 min promoted the cracking of the microcapsules (from 24.49 to 75.36 wt.%). A total ion exchange capacity of 3.56 meq g−1 was achieved. The large ion exchange rate and capacity observed confirm that the sulfonation of the shell makes easier the mobility of the metallic ions from the liquid phase to the extractant agent phase through the shell. It was also observed that the presence of DEHPA into the microcapsules makes them more selective than a conventional ion exchange material.