Removal efficiency for heavy metals ions with granular resin and fibrous adsorbent

Abstract

Pollution of wastewater in the battery industry with heavy metals such as Ni(II), Zn(II) and Pb(II) is an alarming environmental threat posing significant hazard to human, animal and aquatic life. Removal of these metal ions by ion exchange resins has been widely practiced. However, ion exchange technology has some limitations such as high cost of resins and slow kinetics of adsorption. In this study, a new sulfonated fibrous adsorbent (SFA) in a form of sulfonic acid containing poly(glycidyl methacrylate) (PGMA) grafted onto polyethylene (PE) nonwoven fabric was prepared by radiation induced graft copolymerization (RIGC) of glycidyl methacrylate (GMA) and subsequent sulfonation reaction. The obtained adsorbent was characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectrometer combined with attenuated total reflection (FTIRATR) to confirm the incorporation of PGMA and sulfonic acid groups. The performance of the SFA under various treatment conditions pertaining to equilibrium isotherms, kinetics, and breakthrough curves of selective adsorption of Ni(II), Zn(II) and Pb(II) from aqueous solutions were evaluated. The adsorption parameters were optimized using a response surface method (RSM) in both batch and fixed bed column modes through the central composite rotatable design (CCRD). Similar experiments were carried out with commercial granular sulfonated ion exchange resin (Dowex 50W) and used for comparison. The adsorption isotherms of the the tested metal ions on the new adsorbent was found to fit Freundlich model whilst the breakthrough curve followed Thomas model. The optimum parameters for adsorption on SFA in a batch mode were pH of 4.5-7.5 and contact time of 1.0-1.5 minutes for removal of > 90% of Zn(II) and Pb(II). Particularly, a time of less than 3.5 minutes was needed for 95% removal of Ni(II) from solution with 3 mg/L concentration. The column performance of the SFA with respect to combination of solute removal efficiency, resin utilization efficiency and breakthrough time, known as response function (RF), revealed that the highest value of RF was found at a flow rate of >15.2 mL/min and bed height of 5.2 cm. The results of this study suggest that the new fibrous adsorbent has higher adsorption capacity and faster kinetics than commercial granular resin (Dowex 50W). Thus, SFA is considered a potential substituent resin for removal of heavy metal ions from aqueous solutions.