Graphene nanosheets, two-dimensional carbon nanomaterials, have
received significant attention due to the unique electronic, mechanical
properties, large surface areas 18 (theoretical value of 2600 m2/g) 20, excellent electronic conductivity, high chemical stability
and low manufacturing cost 21. Graphene displays high ?-conjugation and hydrophilic properties
however the functionalization of graphene is a requirement to improve the
chemical affinity for specific guest molecules and facilitate the dispersion in
aqueous media 22. Graphene oxide (GO)  has gained considerable attention as a
significant biosorbent (which is similar to carbon nanotube) due to presence of
plenty oxygen atom on the backbone in the form of epoxy, carboxyl and hydroxyl
groups protruding from its layers that can bind to dyes through electrostatic
interaction in addition to the high surface area 19. However, the surface of GO sheets are highly negatively charged
when dispersed in water due to the ionization of carboxylic acid and hydroxyl
groups on the GO sheets. This negative charge limits their application on the
adsorption of negatively charged dyes. Graphene oxide, glutaraldehyde,
crosslinked chitosan and CS/GO showed enhanced adsorption capacity for Au(??)
and Pd(?), 23. A
three-dimensional Chitosan/vacuum-stripped (VSG) grapheme/polypyrrole interface
was fabricated for dopamine detection. The sensor exhibits good selectivity,
high sensitivity, low detection limit and good sensing performance in human
serum samples 23, 24. A hierarchical
porous CS/VSG/PPY scaffold was prepared via a two-step strategy involving
freeze-casting and electrochemical polymerization techniques. To the best of
our knowledge, there is no reported study on the synthesis of PPC/GO
nanocomposite by a chemical method, the performance of the nanocomposite still
not reported as an adsorbent. With the purpose of developing low cost, with
high-quality composite pushing us in the present work to synthesize PPC/GO
nanocomposite via in-situ polymerization of PY in CS/GO dispersion.
Characterization of the composite has been carried out using Fourier
transformed infrared spectra (FTIR), scanning electron microscope (SEM),
transmission electron microscope (TEM) and X-ray diffraction pattern techniques
(XRD). The adsorption of ponceau 4R (as a model) into the nanocomposite was
studied. The kinetics and isotherm of the adsorption have been discussed. The
difference between CS/GO, GO and the PPC/GO nanocomposite toward the adsorption
of ponceau 4R was considered. Various parameters such as initial concentration
of dye, amount of adsorbent, contact time, temperature, pH, adsorption
isotherms, and kinetics were studied, Also desorption process was tested to
study the reusability of sorbents.