By polymerizing acrylonitrile in the presence of ammonium persulfate as an initiator and Pterocladia capillacea-activated carbon (P-AC) as a filler, a composite material polyacrylonitrile/Pterocladia capillacea-activated carbon (PAN/P- AC) was developed. By reacting hydroxylamine with the composite's nitrile groups, the prepared composite was functionalized by amidoximation. FTIR spectrometry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analysis were all applied to thoroughly characterize the fabricated adsorbent. For the treatment of Cr(VI) ions from synthetic solutions, the adsorption properties of amidoximated polyacrylonitrile/Pterocladia capillacea-activated carbon (PAO/P-AC) were investigated. The pH effect, uptake kinetics, adsorption isotherms, and thermodynamics studies were used to characterize adsorption properties. As a kinetic model analysis, the data confirmed that the pseudo-second-order rate equation matched well the adsorption process. With coefficients of determination (R2) of 0.9998, the Tempkin isotherm model had the lowest error, suggesting that it is the best fitted model to describe this adsorption mechanism. Thermodynamic parameters demonstrated that Cr(VI) adsorption was endothermic.

    Abstract
    1 Introduction
    2 Materials and methods
        2.1 Chemicals
        2.2 Composite fabrication of polyacrylonitrilePterocladia capillacea-activated carbon [PANP-AC]
        2.3 Characterization
        2.4 Point of zero charge (pHPZC)
        2.5 Adsorption experiments
        2.6 Error analysis
    3 Results and discussion
        3.1 Characterization
        3.2 Sorption study
        3.3 Impact of Cr(VI) ions initial concentration and isotherm study
        3.4 Thermodynamic study
        3.5 Regeneration studies
        3.6 Mechanism of Cr (VI) adsorption on PAOP-AC
        3.7 Review of the current study's findings in light of other studies
    4 Conclusions
    Acknowledgements 
    References

• Amany G. M. Shoaib(Environment Division, National Institute of Oceanography and Fisheries, Department of Chemistry, Faculty of Science, Alexandria University)
• Ahmed El Nemr(Environment Division, National Institute of Oceanography and Fisheries)
• Amany El Sikaily(Environment Division, National Institute of Oceanography and Fisheries)
• Mamdouh S. Masoud(Department of Chemistry, Faculty of Science, Alexandria University)
• Mohamed S. Ramadan(Department of Chemistry, Faculty of Science, Alexandria University)