Microwave preparation of raw vermiculite for use in removal of copper ions from aqueous solutions.

This study sought to determine optimum conditions for the microwave exfoliation of raw vermiculite and examined the removal characteristics of copper ions from water by the processed vermiculite. When 100 g of raw vermiculite was irradiated at 440 W for 330 s, 66% of the raw vermiculite was exfoliated. The dry density and specific surface area of the exfoliated vermiculite were 0.28 g/cm3 and 54.6 m2/g, respectively. When considering the dry density (2.78 g/cm3) and specific surface area (11.1 m2/g) of the raw vermiculite, microwave irradiation resulted in an approximate 10 times expansion and a five-fold increase in specific surface area. Serial batch tests were conducted to determine the removal characteristics of the exfoliated vermiculite for copper ions in aqueous solutions. Copper was most effectively removed by exfoliated vermiculite with an initial pH of 5. Exfoliated vermiculite at this pH also produced the highest first-order rate constants and instantaneous partition coefficient. These results indicate that exfoliated vermiculite can be prepared by microwave irradiation instead of conventional heat processes for use as a copper ion adsorbent.