No abstract

Nowadays polyethylene terephthalate (PET) bottles are commonly used as food containers as they are lightweight. PET bottles contain antimony (Sb) and phthalate compounds. In contact with food, antimony and phthalate molecules could migrate from the inner surface of a PET bottle to the food. Therefore, we studied the effect of NaCl concentration in PET bottles on the leakage of antimony and phthalates. It was found that the concentration of antimony leached into the solution was about 6 ngl−1 after 5 days storage at room temperature in the absence of NaCl. Increasing NaCl concentrations to 6% caused a decrease in the amount of soluble antimony in the solution to 2 ngl−1 under the same conditions. In addition, the maximum leakage of phthalate compounds of about 130 ngl−1 occurred after 35 days of storage at 60 °C in 0.1% NaCl. It was found that the leakage of phthalate compounds decreased at higher NaCl concentrations (NaCl 0.5%–30%). Higher NaCl concentrations led to a decrease in the migration of antimony and phthalate compounds into the solution. This might be due to the fact that antimony and phthalate compounds form complexes with NaCl. However, the leakage of these compounds was lower than the standard guidelines of the United States Environmental Protection Agency for drinking water.

Modification of bagasse fly ash (BFA) and the adsorption mechanism of antimony (Sb) by modified BFA were studied. It was found that BFA grafted with acrylic acid (BFAG) and BFA treated with hydrochloric acid (BFA/HCl) led to a decrease in the pH of the zero point of charge (pH) of the adsorbents. The pH of BFA, BFAG, BFA/HCl and activated carbon (AC) were 8.3, 6.4, 6.2 and 8.2, respectively. The maximum adsorption capacities (Q) of Sb by BFA, BFAG, BFA/HCl and AC were 0.14, 0.34, 0.38 and 0.29 mg Sb/g adsorbent, respectively. Modified BFA had Q higher than AC although the BET surface area of AC was the highest. This was due to the system pH of BFAG and BFA/HCl was 5.20-6.00 and the pH of BFAG and BFA/HCl accounted for 6.4 and 6.2, respectively. Therefore, the adsorbent surface had a positive charge, resulting in increasing adsorption of Sb.