Poly -rich extraction

Analysis by XPS after incorporation of the linear or dendritic cationic polymers showed an increase in the atom % N consistent with incorporation of an N-rich polycation. The polyvalent interactions between the cationic polyelectrolytes and the poly(sodium acrylate)graftson PE were stable to Soxhlet extraction with 95% ethanol, repeated acid/base treatment, and soaking or sonication in isopropanol and THE However, in these cases, simple acid treatment did not release the cationic polymer as was the case with PAA/Au grafts even though grafting in both cases was reportedly ionic and not covalent. 

Niobium (formerly called columbium) and tantalum occur together in the mineral columbite (Fe,Mn)(Nb,Ta)20g. When the mineral is Nb-rich, it is called niobite and when Ta-rich, tantalite. Fusion of the ore with alkali gives poly-niobates and -tantalates, and further treatment with dilute acid yields Nb205 and Ta205. One method of separation utilizes the more basic character of Ta at a controlled concentration of HF and KF in aqueous solution, the oxides are converted to K2[NbOF5] and K2[TaFy]. The former is more water-soluble than the latter. The modem separation technique is fractional extraction firom aqueous HF solution into... 

---