Anal. Methods Environ. Chem. J. 4 (3) (2021) 5-20
Research Article, Issue 3
Analytical Methods in Environmental Chemistry Journal
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Adsorption and determination of Lead in water and human
urine samples based on Zn
polycaprolactone nanocomposite by suspension micro solid
phase extraction coupled to UV–Vis spectroscopy
Negar Motakef Kazemi
and Masomeh Odar
Department of Medical Nanotechnology, Faculty of Advanced Sciences and Technology, Tehran Medical Sciences,
Islamic Azad University, Tehran, Iran.
Department of Nanochemistry, Faculty of Pharmaceutical Chemistry, Tehran Medical Sciences,
Islamic Azad University, Tehran, Iran
Today, the safety of water resource is the most important challenges
which was reported by health and environment organizations.
Water pollution can be created by hazardous contaminants of
environmental pollutions. Lead as a heavy metal has carcinogenic
effects in humans. Metal organic framework (MOF) is a highly
porous material with different application. The Zn
is a good candidate of MOF based on zinc metal (Zn-MOF) with
potential adsorption/extraction. In this work, Zn
MOF as polycaprolactone (PCL) nanocomposite were applied for
lead adsorption/extraction from 50 mL of aqueous solution by ultra-
assisted dispersive suspension-micro-solid phase extraction procedure
(USA-S- µ-SPE) at pH=8. The samples were characterized by the
FTIR, the XRD analysis, the FE-SEM and the BET surface area.
The effect of parameters was investigated on lead absorption before
determined by UV–Vis spectroscopy. The linear range, the detection
limit (LOD) and enrichment factor of adsorbent were obtained 0.05-1
mg L
and 48.7, respectively (r = 0.9992, RSD%=3.65).
The absorption capacity of Zn
(DABCO) MOF for 50 mg L
of standard lead solution were obtained 133.8 mg g
for 0.25 g of
adsorbent. The results indicate that this nanocomposite can have a
good potential to develop different adsorbents.
Metal organic framework,
Suspension-micro-solid phase
extraction procedure
Received 25 May 2021
Revised form 23 Jul 2021
Accepted 9 Aug 2021
Available online 28 Sep 2021
*Corresponding Author: Negar Motakef Kazemi
1. Introduction
Heavy metals are considered one of the major
pollutants with harmful effects on the environment
and living organisms [1]. Lead is one of heavy metals
with many industry applications. Lead element is a
very strong poison and major environmental health
problem. This non-biodegradable pollutant can be
caused detrimental effects on human health [2]. The
     
lead as a hazardous material that needed to protect
the health of workers, children and women of
childbearing age. Threshold limit value (TLV) is the
weighted average concentration of the risk factor
in the atmosphere [1-3]. According to the results
of workers in battery storage plants, TLV (working
day of eight hours) was obtained about 0.1 mg m
and normal lead concentration in urine of workers
    
. The US Environmental
Anal. Methods Environ. Chem. J. 4 (3) (2021) 5-20
a reference value in bottle and drinking water [3]. The
lead effects on human health and causes the different
diseases in humans such as, CNS defect, the nerve
system damage, the renal/liver/bone dysfunction. The
organic lead compound such as Triethyl and methyl
lead with the Pb(II) as inorganic lead
are toxic for
the humans [3]. Lead emitted to environment with
-Pb and Pb(II) forms and can be
dispersed by oil/gasoline additives [4]. The organic
lead is used in for industries, which can simply enter
to human body by the skin and respiratory system.
The organic lead with good hydrophobicity in organic
solvent and foods has toxic effect in humans [5]. So,
determination lead in water and human liquid samples
(urine) is very important. Various methods have been
developed to removal of each toxic heavy metal from
water [6,7] such as the chemical precipitation [8],
the ion exchange [9], the reverse osmosis [10], and
the adsorbent process [11]. Recently, lead adsorbent
from aqueous solution is a real challenge due to use
widespread all over the world [12]. The adsorption
       
for lead removal from wastewater [13]. The various
adsorbents included, the graphene/graphene oxide
[14]      [15], the
carbon nanotubes (CNTs) [16], the magnetic doped
with carbon quantum dots(MDCQDs) [17], and the
silica nanostructure [18] were widely used for lead
extraction in water samples. Metal organic frameworks
(MOFs) are a new class of porous coordination
polymers with a variety of applications [19, 20]. They
are formed of organic ligands as linkers and metal
ions or clusters as metal centers [21, 22]. Recently,
the MOFs have attracted a great attention because
of unique properties [23, 24]. Zn
MOF is metal organic framework based on
zinc metal (Zn-MOF) by connection of Zn
units and 1,4-benzenedicarboxylate (BDC) and
1,4-diazabicyclo [2.2.2] octane (DABCO) ligands
via self-assembly such as solution [25], solvothermal
[26] and other methods. The common adsorbent
compounds have expanded based on MOFs [27].
(DABCO) MOF was loaded with various
materials such as mercury [28], the gentamicin [29],
the Pd(II) [30], the methane [31], the azobenzene [32]
and etc.
Easy separation of sorbent from the water is
metals during treatment. Therefore, the adsorbents
were developed based on magnetic [33-36] and
polymer [33, 37] materials. Polycaprolactone is one
of the most common polymers for the removal of
heavy metals from aqueous solutions as hazardous,
carcinogenic, and toxic pollutants. According to
for lead adsorption [38]. Also in another report,
cyclodextrin-polycaprolactone titanium dioxide
nanocomposites were used as a adsorbent for the
removal of lead in aqueous waste samples [39]. The
different techniques included, the graphite furnace
coupled with atomic absorption spectrometry(GF-
AAS) [40], the anodic stripping voltammetry (ASV)
[41]     
(F-AAS) [42], the inductively coupled plasma
atomic emission spectrometry (ICP- AES) [43] and
the UV-Vis were used for lead determination in water
samples. In present study, Zn
MOF/PCL nanocomposites were prepared by a
simple method and lead absorption was investigated
by MOF and its nanocomposites from aqueous
solution at optimized pH.
2. Experimental
2.1. Reagents and Materials
All reagents with high purity and analytical
grade were purchased from Merck (Darmstadt,
Germany). Ultra-pure water was used for the
preparation of all reagent’s solutions. Zinc acetate
ehydrate (Zn(Oac)
O, CAS N:5970-45-6,
Sigma, Germany), 1,4 benzenedicarboxylic acid
(CAS N: 652-36-8, Sigma), 1,4-diazabicyclo [2.
2.2] octane (CAS N: 280-57-9, Sigma), N,N-
dimethylformamide anhydrous (DMF, CAS N: 68-
12-2) were used for synthesis of MOF. The lead
502-44-3, Sigma, 1400 g mol-1, molecular weight)
were applied for preparation of lead and polymer
solution respectively.