2.6. Endosulfan removal experiments in soil
Endosulfan (40 mg/kg) was prepared in 10 g of sterile sandy
loam. After two hours, 20 mL of acetate buffer and pre-cleaned
Zn(0) (0.1 g, 0.5 g, 1.0 g) were added and the initial pH value of
the reaction system was 4. The initial pH of the solution was
adjusted to the designated value with HCl or NaOH. The reaction
tubes were then sealed and shocked in a constant-temperature
shaker at 25 ± 0.1 C and 180 rpm. Control experiments were also
performed according to the above procedure (without Zn(0)). Each
experiment included three repetitions and the reaction time was
180 min. Samples were extracted with ethyl acetate by vortex and
centrifuged and then analyzed by GC. The extraction method was
with high recovery (above 83.59%) and less interference from
impurities.
Phosphate buffer (pH 7) and carbonate buffer (pH 9) were
chosen to evaluate the effect of pH on the reaction according to the
above procedure.
Shin et al. (2008) stated that surfactant might modify the surface
property of the metal and the reduction on the surface of metal