Preparation and characterization of an organic/inorganic hybrid sorbent (PLE) to enhance selectivity for As(V)

다국어 초록 (Multilingual Abstract)

<P><B>ABSTRACT</B></P> <P>For the selective removal of arsenate (As(V)) a hybrid sorbent was prepared using a non-toxic natural organic material, chitosan, by loading a transition metal, nickel. The immobilization of nickel was achieved by coordination with a deprotonated amino group (NH<SUB>2</SUB>) in the chitosan polymer chain. The amount of nickel was directly correlated to the presence of the amino group and was calculated to be 62mg/g. FTIR spectra showed a peak shift from 1656 to 1637cm<SUP>−1</SUP> after Ni<SUP>2+</SUP> loading, indicating the complexation between the amino group and nickel, and a peak of As(V) was observed at 834cm<SUP>−1</SUP>. An increase of sulfate concentration from 100mg/L to 200mg/L did not significantly affect As(V) sorption, and an increase in the concentration of bicarbonate reduced the As(V) uptake by 33%. The optimal pH of the solution was determined at pH 10, which is in accordance with the fraction of HAsO<SUB>4</SUB> <SUP>2−</SUP> and AsO<SUB>4</SUB> <SUP>−3</SUP>. According to a fixed column test, a break through behavior of As(V) revealed that selectivity for As(V) was over sulfate. Regeneration using 5% NaCl extended the use of sorbent to up to uses without big loss of sorption capacity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A natural biopolymer, chitosan, was used to selectively remove As(V). </LI> <LI> A deprotonated amino group was coordinated with nickel by LAB. </LI> <LI> Immobilized nickel played a key role in the selective removal of As(V) over SO<SUB>4</SUB> <SUP>2−</SUP>. </LI> <LI> The breakthrough sequence is followed: As(V)>SO<SUB>4</SUB> <SUP>2−</SUP> >HCO<SUB>3</SUB> <SUP>−</SUP> >NO<SUB>3</SUB> <SUP>−</SUP> >Cl<SUP>−</SUP>. </LI> <LI> The PLE is reused without a significant loss of As(V) uptake up to 10 times. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>