Development of Adsorbents to Remove Trivalent Chromium from Aqueous Solutions Using Radiation Grafting Technique.

In this study, radiation-grafted adsorbents were developed and evaluated for their capacity to remove trivalent chromium (Cr3+) from aqueous solutions. The adsorbents were prepared through electron beam induced grafting of glycidyl methacrylate (GMA) onto polypropylene nonwoven fabric (PP), followed by post-grafting functionalization of the PP-g-PGMA with ethylenediamine (EDA), iminodiacetic acid (IDA), phenylphosphonic acid (PPO), and phenylphosphinic acid (PPI). The Fourier-transform (FTIR) spectroscopy and thermogravimetric analysis (TGA) results suggest that the PP substrate was successfully grafted and functionalized. Among the adsorbents evaluated, the EDA functionalized PP-g-PGMA showed the best performance, removing 90-99.5% of Cr3+ from 50 mL of 10 ppm Cr3+ solution at pH 3.5 using an adsorbent with 0.159 mmol EDA groups after adsorption for 24 h with continuous stirring at room temperature. The bound Cr3+ was stripped off from the spent adsorbent by 0.5 M HCl at 70% efficiency, which was also performed for 24 h of continuous stirring at room temperature. The adsorption of Cr3+ by the EDA-functionalized fabric fit best with the Langmuir adsorption isotherm (R2 = 0.967), possibly indicating a monolayer coverage of the adsorption sites. Moreover, the EDAfunctionalized fabric was found to be highly selective toward Cr3+, even in the presence of high concentrations of cations commonly present in tanning wastewater such as Na, Mg, and Fe. The results suggest the potential of the EDA functionalized PP-g-PGMA adsorbent to be used in the treatment of tanning industry wastewater containing ppm levels of Cr3+. [ABSTRACT FROM AUTHOR]