الفهرس 
Characteristics of heavy metals and its environmental impactOnly 14 pages are availabe for public view
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Abstract
The main conclusions of this work are summarized in this chapter:
Iron oxide (α-Fe2O3) nanoparticles were synthesized successfully by solid state chemical reaction method. The nanoparticles were embedded in the PVA polymer matrix (PVA/α-Fe2O3) for adsorption of heavy metal (lead ion). Then, these nanoparticles mixed with the conductive polymer (PAni) by solid state chemical reaction for synthesis (PAni/ α-Fe2O3) nanocomposites. Ionizing radiation has been utilized in many aspects of modifying polymeric materials. The present study-divided into three groups:-
group (A):
Hematite nanoparticles (α-Fe2O3) were synthesized successfully by solid state chemical reaction technique. The obtained results indicated that:
α-Fe2O3 has advantage of low band gap, chemical stability, low cost and nontoxicity.
With increasing the annealing temperature, the crystallite size increase, surface pressure decreases as well as lattice strain decreases.
The sample annealed at 800°C has better and high XRD peak intensity of the nanostructures of XRD spectrum which means the formation of the phase of iron oxide (α-Fe2O3).
The increase in the coactivity with annealing temperature indicated the single domain nature in the samples as well as the material (α-Fe2O3) is in superparamagnetic with grain size around 50 nm.
The value of direct band gap of iron oxide nanoparticles (α-Fe2O3) decreased from ∼3.3 eV to ∼2.22 eV for the α-Fe2O3 nanoparticle with increasing temperatures due to increase in the grain size.
The reduction of 4-nitrophenol to aminophenol with the rate constant about 0.0013 min-1 which means that α-Fe2O3 nanoparticles is considered a good catalytic agent, the factors affecting on the catalytic efficiency are reaction time, concentration of iron oxide and concentration of NaBH4.
group (B):
from the obtained results of the second part in the present study it can be seen that:
Simple method was used to fabricate PVA/ α-Fe2O3 using different concentration of hematite (0.05, 0.1, 0.3) mg.
The synthesis samples were exposed to γ-irradiation dose at 30 kGy to form cross-linked network.
PVA/α-Fe2O3 nanocomposites are characterized by (XRD and FTIR) and investigated the effect of gamma irradiation on the structural analysis.
Further investigation for the removal of lead Pb by PVA/ α-Fe2O3 nanocomposite were also observed in this study.
Factors such as PH and adsorbent dosage significantly affected the removal of lead (Pb) by PVA/ α-Fe2O3 nanocomposite.
Results also demonstrated that lead (Pb+2) removal was very sensitive to solution pH between 2.0 and 5.5 with the highest removal capacity at solution pH 4, decreasing sharply with increasing pH.
Maximum adsorption capacities of 96.06% was achieved for Pb2+ concentration of 20 mg/L in aqueous solution, contact time of 2.5 h and nano adsorbent concentration of 20 mg/L (0.3mg α-Fe2O3/PVA nanocomposites per 20mL solution) .
This investigation was necessary to improve knowledge of potential applications of PVA- hematite nanocomposite as adsorbent for lead removal in water treatment.
group (C):
PAni/ α-Fe2O3hybrid nanocomposites synthesis by solid state synthesis route to modify their properties. The obtained results indicate that:
The characterizations of synthesized hybrid nanocomposites were carried out using XRD, FTIR, techniques.
XRD analysis of PAni/ α-Fe2O3 hybrid nanocomposite indicates, presence of PAni has no influence on the crystalline performance of α-Fe2O3.
FTIR analysis demonstrates a strong chemical interaction between different loading of α-Fe2O3 nanoparticles and PAni matrix with shift of characteristic bands toward higher wave numbers.
Results of dc electrical conductivity shows a decrease in conductivity with increasing content of α-Fe2O3 in PAni matrix.
A decreased conductivity with respect to high particle loading is due to the semiconducting behavior of α-Fe2O3 indicating a strong dependence on the weight percent α-Fe2O3 in PAni matrix.
Dc electrical conductivity of PAni/ α-Fe2O3 hybrid nanocomposites shows an increase in conductivity with gamma irradiation dose (50kGy) may be due to the formation of polarons created at the defects site, which moves towards the polymer backbone. This implies that radiation induced degradation becomes effective and hence increase the motion of free radicals, there by increases the conductivity.