Characterization and Performance Analysis of an Adsorptive Polyacrylonitrile based Hydrogel for Heavy Metals Removal

Adsorption is a key technology for heavy metals removal from industrial effluents. The use of adsorbent polymers is considered to be an attractive solution for wastewater treatment due to their high selectivity for certain heavy metals. Through the current study, an adsorptive polyacrylonitrile based hydrogel blend was used to examine heavy metals removal in simulated effluents incorporating chromium and nickel. Moreover, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) in conjunction to an Energy Dispersive X-Ray Spectroscopy (EDX) were used for characterization of the polymeric blend structure. Finally, for surface evaluation, the specific surface area and the pore size distribution Brunauer-Emmett-Teller (BET) analysis techniques were used together with electrical conductivity measurements. The obtained results from FTIR showed the appearance of the original bands of raw materials (polyacrylonitrile (PAN), polyvinyl alcohol and polyaniline (PAni) and the change of the peaks position confirmed the hydrolysis and combination of starting materials into the polymeric blend. Surface morphology studies showed that this gel has porous surface with an average pore size and surface area of 0.73 nm and 17.3 m2 /g, respectively. Moreover, Electrical conductivity measurements indicated the presence of PAni in the polymeric blend assisted in the increase in conductivity of PAN. Finally, the different parameters of the polymeric hydrogel blend were investigated through swelling water ratio (SWR) and conventional adsorption processes at different operating conditions such as; initial salt concentration, pH and contact time. The maximum chromium adsorption results were (12.44 mg/g for 10 mg/L initial salt concentration), (10.46 mg/g for 5.5 pH) and (4.91 mg/g for 1 hr. contact time). Whereas, the maximum nickel adsorption was (7.67 mg/g for 20 mg/L initial salt concentration), (7.57 mg/g for 7 pH) and (6 mg/g for 2 hrs. contact time).