Chitosan (CHT), is a non-toxic and natural
polymer consists reactive functional groups such as hydroxyl and primary amino groups
for complexation that readily interacted with transition metals in natural
biological media. Due to special structure of CHT, this matter displays several
properties including doping probability, gel-forming potential, cost-effectiveness,
unique mechanical stability and special permeability. So, CHT can be widely
used for adsorption of various organic compounds and heavy metals.
In the recent years, refinement the
molecules of CHT by some materials such as carbon nanotubes, metal
nanoparticles and redox reagents to causes the improvement of electric
adsorption possibility of CHT.
In the recent articles, improvement of
the sensitivity and conductivity of CHT are created by immobilization of CHT on
metal oxide nanoparticles. Furthermore, these nanoparticles are able help to increases
the quality of a adsorbent for example high catalytic yield and large reactive
surface of the adsorbent surface. Among of extremely applicable properties of
nanoparticles, the Fe3O4 nanoparticles are interest due
to minor toxicity and its biocompatibility. Thus, combination of CHT and Fe3O4
nanoparticles presents special nanocomposites that create the properties of
ideal nanoparticles such as fast biodegradation, unique electrical properties
and significant surface-to-volume ratio.
Existence of contamination related to transition
metals is critical because their increasing concentration in the ecosystem and
hence appeared food chain1. The determination and elimination of
poisonous transition metal ions from sewage are imperative from an
environmental viewpoint. The main source of Cd(II) such as alloy and mining
factories, batteries, paint and pigments industries and electroplating
contaminate the environment due to disregard to industrial wastewaters.
In recent years, much attention has been
directed to the use of different low-cost and active adsorbents for the
elimination of injurious and poisonous materials, new hybrid organic or
inorganic structures have been lately
proposed as heavy metals adsorbents2.
Cupper is one of the most important transition
metals with a considerable risk potential to mans’ society that makes cancer,
pain in bone and damage of kidney. Initial methods for elimination of metals
from the sewage of factories consists bio sorption, redox process, coprecipitation,
ion exchange and membrane and distillation techniques. However the techniques
of adsorption submit several benefits such as low cost-method, at least of
produced mud, maximum yield of elimination of metal ions, the regeneration and recovery ability
In comparison with different traditional
treatment methods, such as membrane separation coprecipitation, redox
techniques, ion exchange, photocatalytic processes and filtration, adsorption
is one of the simplest and concern processes with several benefits accompanied
with no surplus mud for high efficiency to remove metal ions. Besides, the adsorption is quite
popular in terms of convenience, availability, profitability and design. The
common sorbents in metal adsorption, including carbon, resins organic molecules
and micro-algae have random adsorption sites that decrease the adsorption efficiency
of metal removal3.
Considering to these subjects, sensitive
analytical methods for the determination the most of heavy metals in industrial
sewages are required. Its determination usually needs pre-concentration techniques
due to minor amount of analyte and require to elimination the interferences
from complex solution. For this, the direct determination by the most common
analytical methods is a hard task. More valuable and sophisticated techniques,
i.e. ICP-OES, suffer from strong interferences that can be overcome only using
more costly high resolution4.
In the current study, Fe3O4 nanoparticles were immobilized on CHT (Fe3O4-CHT)
and examined as novel complex chelation materials. This view was based on this
subject that the available functional groups of CHT interacted with transition
metals and thereby formed the chelating agents. In addition, CHT is due to lack
of some surface groups such as amines has minimum environmental effects.
Because the main parameters of pH, metal ion concentration, mass of adsorbent
and time had the highest effect on removal’s process, so these parameters were
selected and studied by experimental design5.
Investigation of removal methods by classical techniques
accomplished by maintaining some parameters at an unlimited fixed level doesn’t
consider the multiple effects of all main factors. This technique is usually
time consuming and need numerous unreliable experiments to assign optimum
conditions. For these purpose, some mathematical and statistical method such as
Response Surface Methodology (RSM) are used for compensate of all effecting
variables and therefore are eliminated the restrictions of a classical method6.
RSM is a combination of mathematical and statistical
techniques suitable for optimization of affecting parameters and can be applied
to estimate the relative significance of all main variables despite the mutual
interactions. The special and major target of RSM is to determine the optimum zone
and the best practical conditions which lead the best removal. The
accomplishment of this statistical operational methods (RSM) in adsorption
process development can succeeded in improved output efficiencies, decreased
process variability, closer accommodation of the output response to nominal and
target requirements and minimum of time and overall costs.