Synthesis of graphene oxide-based poly(p-aminophenol) composite and its application in solid phase extraction of trace amount of Ni(II) from aquatic samples.

The results of investigations about the polymerization of p-aminophenol in neutral-weak alkaline medium (pH = 7-8) in our lab showed that the produced polymer which was insoluble in water and soluble in methanol has high tendency to form selectively a blue complex with Ni(II). Investigations into the chemical structure of polymer showed that polymer has a special structure, similar to polyamine in which the aromatic rings are connected through O-bridges. Based on these data, it was decided to polymerize p-aminophenol in situ on graphene oxide (GO) and use as a new sorbent for selective separation and preconcentration of trace amount of Ni(II) from water samples. By this, the rate of sorption of Ni(II) will also be increased considerably with respect to GO alone. Resulting composite (GO-Pp-AP) was characterized by FT-IR, XRD, FE-SEM, and EDS. The obtained data confirmed the uniform growth of the polymer on the GO and the absence of granular particles. The composite shows high tendency and high rate of sorption of Ni(II) and consequently was utilized for solid phase extraction (SPE) of Ni(II) ions before its determination by flame atomic absorption (FAAS). The effects of important parameters on the recovery of Ni(II) were investigated. The presence of foreign ions has no meaningful effect on the recovery percentage of Ni(II). Under the optimum conditions, limit of detection and relative standard deviation were found to be 0.70 μg L-1 and 1.8% (for n = 6; at 20 μg L-1 of Ni(II)), respectively. Testing the standard reference material and analyzing the spiked real samples exhibit that the procedure can be successfully employed for determination of Ni(II) in natural water and wastewater samples. Graphical abstract ᅟ.