Polyethyleneimine Coated Polyacrylonitrile Cellulose Membrane for Colorimetric Copper(II) Determination

Abstract

Polyethyleneimine (PEI)-polyacrylonitrile (PAN)-cellulose membrane (PEI-PAN cellulose membrane) was developed by immobilizing PEI onto PAN coated cellulose support via electrostatic force to be used for determination of Cu(II) by colorimetric method. The membrane was prepared in two-step process, in which 4% PAN solution was prepared and coated onto the membrane via filtration method, followed by the immersion of the dried PAN-cellulose membrane in the 2% PEI solution. The morphologies of the PEI-PAN membranes were investigated with field emission scanning electron microscope. The results confirmed the presence of a coated layer on the surface. Infrared spectra of before and after coated samples were obtained by Fourier transform infrared (FTIR) spectroscope. The results showed that there were NH2 functional group of PAN and PEI with their characteristic transmittance peaks. Determination at the parts per million level of Cu(II) (0.5–2.0 mg L–1) was achieved by filtration of a sample solution and simultaneous colorimetric analysis using a UV-Vis spectrophotometer (at 650 nm). Cu(II) ion formed the light blue cupramine complex with PEI immobilized on the membrane by filtration of a 50 mL sample solution buffered with 0.01 M dihydrogen phosphate (pH 7). Energy dispersive X-Ray fluorescence spectrum of the Cu(II) detected membrane confirmed the capability of Cu(II) extraction of the PEI-PAN cellulose membrane from the water samples. The detection limit of the Cu(II) determination by this method was found to be 0.27 mg L–1. The accuracy and precision of the method were estimated by Cu(II) determination at 0.5 and 2 mg L–1 of Cu(II) solutions and the results were accurate with above 89% recovery percentage and below 5.5% relative standard deviation. Interference ions were studied and found that Fe(III) and Zn(II) slightly interfered with the Cu(II) determination. The present method was tested for the detection of treated textile wastewater and tap water spiked with 2 mg L–1 of Cu(II). The test results were acceptable and good to determine wastewater prior to discharge into the environment that could be applied for on-site monitoring of Cu(II) in treated wastewater by filtration detection method.