Use of hydrotalcites for the removal of toxic anions from
aqueous solutions The removal of toxic anions has been achieved
using hydrotalcite via two methods: (1) coprecipitation and (2)
thermal activation. Hydrotalcite formed via the coprecipitation
method, using solutions containing arsenate and vanadate up to
pH 10, are able to remove more than 95% of the toxic anions (0.2
M) from solution. The removal of toxic anions in solutions with
a pH of >10 reduces the removal uptake percentage to 75%. Raman
spectroscopy observed multiple A1 stretching modes of V−O and
As−O at 930 and 810 cm−1, assigned to vanadate and arsenate,
respectively. Analysis of the intensity and position of the A1
stretching modes helped to identify the vanadate and arsenate
specie intercalated into the hydrotalcite structure. It has been
determined that 3:1 hydrotalcite structure predominantly
intercalate anions into the interlayer region, while the 2:1 and
4:1 hydrotalcite structures shows a large portion of anions
being removed from solu