Studies on the Mechanism of Cu(II) Ion Sorption on Purolite S 940 and Purolite S 950

Abstract

The aim of the presented research was to investigate the mechanism of sorption of Cu(II) ions on the commercially available Purolite S 940 and Purolite S 950 chelating ion exchangers with the aminophosphonic functional groups. In order to understand better the sorption mechanism, the beads were cut with an ultramicrotome before and after the Cu(II) ion sorption process. The cut beads were examined by scanning electron microscopy (SEM) with an EDX detector. The performed linear profiles of the elemental composition allowed us to examine the depth with which the sorbed metal penetrates into. For further investigations concerning the mechanism of the sorption process, the Fourier transform infrared spectroscopy (FTIR) analysis using the attenuated total reflectance (ATR) technique and the X-ray photoelectron spectroscopy (XPS) methods have been used. The comparison of FTIR and XPS spectra before and after the sorption of Cu(II) ions showed that free electron pairs from nitrogen and oxygen in the aminophosphonic functional groups participate in the process of copper ion sorption. In addition, the microscopic studies suggested that the process of ion exchange between Na(I) ions and sorbed Cu(II) ions takes place on the Purolite S 940 and Purolite S 950. This study concerning the in-depth understanding the of Cu(II) sorption mechanism, using modern analytical tools and research methods could be very useful for its further modifications leading to the improvement of the process efficiency.

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“…The applicability of the PSO model with both the L and the NL regressions was also proved by the fitting plots, which are given in Figure 4d. As was found in the literature, the copper ion adsorption without surfactants followed the PSO model, e.g., the Cu(II) adsorption on the H 3 PO 4 -activated rubber wood sawdust (S BET = 1673.86 m 2 /g) (0.5 g; 100 mL; pH 6; C 0 = 20 mg/L); the PSO model; %R = 80-90% (30 min); the equilibrium time = 240 min; the rate-limiting step: film diffusion (low concentrations) and particle diffusion (high concentration) [52]; the Cu(II) adsorption on Purolite S940 (S BET = 15.8 m 2 /g) and Purolite S950 (S BET = 15.7 m 2 /g) chelating ion exchangers (0.20 g, C 0 = 20 mL of 0.001 M CuCl 2 , agitation speed 180 rpm, T = 298 K, time 2 h); the PSO model; the equilibrium time = 40 min (0.001 mol/L, all ion exchangers); 5 min (0.005 mol/L, Purolite A950) [53]; the Cu(II) adsorption on Purolite S930 (1 g/L C 0 = 100, 300 mg/L, pH = 5, T = 293, 303 K, time 1 min-24 h); the PSO model; %R = 40% (4 h) [54]; the Cu(II) adsorption on Lewatit MonoPlus TP220 (0.5 g; 50 mL; C 0 = 100 mg/L, agitation speed 180 rpm, amplitude 8, T = ambient, time 1 min-4 h); the PSO model; %R = 91-100% (depending on HCl, HNO 3 concentration); the equilibrium time > 120 min (HCl), >60 min (HCl-HNO 3 systems) [30], etc. The literature reports a few examples of Cu(II) adsorption in the presence of non-ionic surfactants [55,56], but the kinetics of the adsorption process in the systems containing heavy metal ions and surfactant is not described in detail.…”

“…Based on the kinetic studies: q = 8.17 mg/g, S940 q = 9.72 mg/g, S950 [53] Cu(II) Purolite S930, ST-DVB FG: iminodiacetic acid 1 g/L; pH 3; 100, 300 mg/L; T = 293, 303 K; t = 1 min-24 h Langmuir, q max = 133.33 mg/g [54] Langmuir, q max = 110 mg/g This paper q max -the maximum sorption capacity, AC-activated carbon, S BET -the Brunauer-Emmett-Teller (BET) surface area, *-with ZnCl 2 activation at 973 K in N 2 atmosphere, FG-the functional groups, ALM-10-the non-ionic surfactant including alkylomonoethers, OS-20-the non-ionic surfactant oxyethylated alcohols.…”