Effect of NaCl on antimony and phthalate compounds leached from PET bottles

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.</jats:p

Preparation of bioadsorbents for effective adsorption of a reactive dye in aqueous solution

The surface of barley straw, an agricultural waste, was modified chemically using a cationic surfactant hexadecylpyridinium chloride monohydrate (CPC) and used as an adsorbent for removal of Reactive Blue 4 (RB4) from aqueous solution. The raw and surfactant-modified barley straws (SMBS) were characterized by Fourier transform infrared and elemental analysis. The stability of CPC adsorbed on straw surface was evaluated by exposing to water and organic solvents. The adsorption was performed on removing RB4 from wastewater in a batch adsorption system. The effects of contact time, initial concentration of dye and pH of solution on RB4 uptake were investigated and discussed. It was found that the removal percentage of RB4 increased with the increase in contact time. Adsorption was favorable at acidic condition and the maximum removal of 100% was obtained at pH 3. Dye-loaded SMBS was stable and percentage of desorption was less than 7% in water. The kinetic studies revealed that the kinetic data fitted well to the pseudo-second-order model. The isotherm study also indicated that RB4 adsorption on SMBS matched well with the Langmuir model other than the Freundlich model. The maximum adsorption capacity determined from the Langmuir isotherm was 29.2 mg g−1 at 25 °C