EFFECT OF pH ON ADSORPTION OF ORGANIC ACIDS AND PHENOLIC COMPOUNDS BY AMBERLITE IRA 67 RESIN

Adsorption of model solution containing organic acids (octanoic and hexanoic acid) and phenolic compounds (rutin, scopoletin and quercetin) on a weak base anion exchange Amberlite IRA 67 resin was studied in a model system. This research was carried out to understand the effect of pH on single and multicompounds studied for its further use in actual system (fruit system). It was shown that the pH dependence of adsorption capacity of weak base anion exchange Amberlite IRA 67 resin had similar increasing trend on organic acids (hexanoic and octanoic acid) and phenolic compounds (rutin, scopoletin and quercetin) studied as pH values increased. In single solution of each phenolic compound, it was observed that total phenolic content (TPC) and antioxidant activity (FRAP and DPPH) gave highest values closer to neutral pH regime. The pH dependence of adsorption capacity in multicompounds solution also showed similar trend for organic acid compounds. Similar trend was also found in multicompounds solution of phenolic compounds in total phenolic content (TPC) and antioxidant activity (FRAP and DPPH). The findings obtained in this study will help to gain better understanding of the complex mechanisms of ion exchange resin and adsorption process involving multicompounds system.

Selection of Ion Exchange Resins for Tungsten and Molybdenum Separation

A solution containing tungsten and molybdenum was acidified using hydrochloric acid, and the ability of several commercial ion exchange resins to separate tungsten and molybdenum was evaluated. The results from the acidification test indicate that when the pH of the solution is adjusted to 7.0, WO42- is polymerized into HW6O215-, while MoO42- is not. The test results of resins selection show that the D213 resin and the D308 resin are superior to other resins in separating low concentrations of tungsten and molybdenum, whereas the D201 resin and the D309 resin are suitable for separating high concentrations of tungsten and molybdenum. The results from the column test indicate that weak-base anion exchange resins are better than strong-base anion exchange resins for both low and high concentrations of tungsten and molybdenum.