Sorption of boric acid and borax by activated carbon impregnated with various compounds

The separation of boron compounds, boric acid and borax from aqueous solution by activated carbon before and after impregnation with various compounds was studied. A series of activated carbons was prepared from coconut shell impregnated with calcium and barium chlorides, citric and tartaric acids. The examined processes were performed in batch and continuous systems under equilibrium and dynamic conditions. Impregnation was found to change the adsorption capacity, suggesting that the nature of the impregnant affects the surface area and sorption characteristics of the sorbent. The results obtained show that the use of barium or calcium as impregnants leads to a decrease of the amount of boron adsorbed. The presence of citric or tartaric acid is essential for the enhancement of the amount of adsorbed boron above that for the untreated activated carbon or the carbon initially impregnated with calcium and barium chlorides. The results are represented in terms of the sorption capacities of the examined materials. Copyright (C) 1996 Elsevier Science Ltd