Dual-Responsive Pectin/Graphene Oxide (Pc/GO) nano-composite as an efficient adsorbent for Cr (III) ions and photocatalyst for degradation of organic dyes in waste water

In this investigation, biopolymer pectin-graphene oxide (Pc/GO) nano-composite was synthesized and the proficiency of nano-composite was investigated for the adsorptive removal of Cr (III) ions and photocatalytic degradation of organic pollutants, methylene blue (MB) and methyl orange (MO) dyes. The resulting nanocomposite (Pc/GO) was systematically characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The photocatalytic and adsorption properties of the nano-composite samples with varying pectin concentrations were evaluated by UV-vis spectroscopy and atomic absorption spectrometer, respectively. Approximately, 98 % of methylene blue (MB) and 87.5 % of methyl orange (MO) dye was degraded in 25 and 90 min, respectively. The nano-composite was found to be highly selective for Cr (III) ions, on the basis of distribution co-efficient values. The suspension of pectin in graphene was prepared by mixing varying amounts of pectin in fixed amount of graphene oxide viz. 0 mg (S-I), 250 mg (S-II), 500 mg (S-III), 750 mg (S-IV), 1000 mg (S-V) in 30 mL deionised water. The adsorption capacity of the samples S-I, S-II, S-III, S-IV and S-V was found to be 1222, 1600, 2100, 2600 and 3333, respectively. The adsorption mechanism on the nano-composite was evaluated by Langmuir and Freundlich adsorption isotherms.