Abstract:
Long-term consumption of arsenic results in severe and permanent health damages. The aim of the study
was to investigate arsenate (As(V)) sorption capacity of termite mound (TM), containing mainly silicon,
aluminum, iron and titanium oxides, under batch adsorption setup. The pattern of As(V) removal with
varying contact time, solution pH, adsorbent dose, As(V) concentration and competing anions was investigated. Dissolution of the adsorbent was insignificant under the equilibrium conditions. Equilibrium was
achieved within 40 min of agitation time. Kinetic data of As(V) adsorption followed well the pseudo-second
order equation (R2 > 0.99). High As(V) removal efficiency (w 99%) was observed over a pH range w 3ew 10,
which is of great importance in the practical application. The Freundlich and DubinineRadushkevich isotherms well described (R2 > 0.99, c2 w 0.05) the equilibrium As(V) adsorption, giving a coefficient of
adsorption 1.48 mg1 1/n
L1/n
/g and a saturation capacity 13.50 mg/g respectively. The obtained value of
mean sorption energy (EDR ¼ 13.32 kJ/mol) suggested the chemisorption mechanism of As(V) adsorption on
TM. The removal of As(V) was significantly decreased in the presence of phosphate ions. The As(V) loaded
adsorbent was successfully regenerated using NaOH solution with insignificant loss of metals. Therefore,
the results of the study demonstrated that TM could be considered as a promising adsorbent for the
treatment of As(V) in drinking water.
