Environmental Engineering Reference
In-Depth Information
OH
N
N
N
OH
figure 7.21
4-(2-Pyridylazo)-resorcinol.
N
N
N
OH
figure 7.22
1-(2-Pyridylazo)-2-naphthol.
water. Also, 1-(2-pyridylazo)-2-naphthol (PANa, Fig. 7.22)-modified MNPs were used for the separation and preconcentration
of Mn
2+
ions from aqueous samples [52]. The detection limit of the proposed method was 0.11 µg⋅l
−1
. A selective solid-phase
extractor (stable in 6 mol/l hCl, common organic solvents, and buffer solutions at ph 2.0-8.0) was prepared based on the mod-
ification of silica gel with 2-((3-silylpropylimino)methyl)-2-hydroxy-1-naphthol (SPIMhN) [53]. This nanosorbent was applied
for the enrichment of trace amounts of Fe
3+
, Pb
2+
, Cu
2+
, Ni
2+
, Co
2+
, and Zn
2+
subsequent to their determination by flame atomic
absorption spectrometry. Sorbent based on gold NPs loaded in activated carbon (AuNP-AC) was modified by bis(4-
methoxysalicylaldehyde)-1,2-phenylenediamine (BMSAPD) [54]. This sorbent (AuNP-AC-BMSAPD) was applied for the
enrichment and preconcentration of trace amounts of Co
2+
, Cu
2+
, Ni
2+
, Fe
2+
, Pb
2+
, and Zn
2+
ions in real samples (recoveries in
the range of 95-99.6% and a relative standard deviations (rSD) <4.0%). Following the optimum conditions, a preconcentration
factor of 200 was obtained for all the metal ions under study with detection limits of 1.4-2.6 ng/ml.
7.6
s-CoNtaiNiNg ligaNds
S-containing ligands are commonly used as sensors; thus, the chelate sensor method for detecting mercury, based on the high
affinity of thiol-containing ligands for the mercuric ion, has been known for a long time [55]. The S-containing ligands, used
for environmental applications, are mainly represented by dithiocarbamates (DTCs). Thus, a dispersive solid-phase
microextraction (DSPMe) with MWCNTs as solid sorbent and ammonium pyrrolidinedithiocarbamate (APDC) as chelating
agent was developed for the determination of selenium in the presence of heavy metal ions and alkali metals [56]. The
Se(IV)-APDC complex was adsorbed on MWCNTs dispersed in aqueous samples, which were then filtered, and MWCNTs
with selenium chelate were collected in a filter. Under optimized conditions, Se can be determined with very good recovery
(97 ± 3%), precision (rSD = 3.2%), and detection limits (from 0.06 to 0.2 ng/ml). The high efficiency of nanometer-sized
γ-alumina coated with sodium dodecyl sulfate-pyrrolidine dithiocarbamate (SDS-4-BPDC) for sorbent solid-phase
extraction was also reported [57]. Sorbent with modified nanometer-sized alumina was used to preconcentrate and separate
cobalt in food and environmental water samples. The proposed method was applied to determine cobalt at trace levels in real
samples such as rice, tobacco, orange, green pepper, black tea, honey, potato, spinach, mangosteen, tomato, strawberry,
carrot, apple, kiwi, mushroom, cucumber, lettuce, milk, wheat sprout, tap water, river water, and sea water with satisfactory
