Application of nanofiltration for acidic waters containing rare earth elements: Influence of transition elements, acidity and membrane stability

Abstract

14Acid mine drainage (AMD) is considered the main environmental problem in mining operation due to its acidity, 15 metal content (Fe, Al, Zn, Cu) and onerous associated treatment cost. However, the presence of relatively high 16 levels of added value elements (rare earth elements (REE)) could make its valorisation economically affordable. 17Membrane nanofiltration (NF) has been postulated as a potential recovery technology because it allows the 18 recovery of a sulphuric acid rich stream and a metal rich stream in one step. In this study, the performance of a 19 semi-aromatic polyamide NF membrane (NF270) in filtering model solutions containing common metals (Ca, Al, 20 Zn) in sulphuric solutions (pH 1.5-3.0) was evaluated. In a second stage, the performance was assessed with the 21 same model solutions but also containing REE. NF270 showed high rejections for metallic ions in solution, 22allowing acid permeation. Ion rejection data were used to determine membrane permeances to ions using the 23 solution-diffusion model considering reactive transport. The stability of the membrane was also studied by 24 comparing performances of a virgin membrane with an aged membrane exposed to 1 M sulphuric acid for 4 25 weeks. Physicochemical changes of membrane properties after ageing were also analysed by ATR-FTIR, AFM and 26 XPS. 27 28

Nanofiltration Membrane Characterization and Application: Extracting Lithium in Lepidolite Leaching Solution

“…The FT-IR spectroscopy of four NF membranes is almost identical, as shown in Figure 2 , which means that the raw materials for preparing these membranes are almost the same. The most striking peaks in Figure 2 a were shown and assigned in Table 2 [ 25 , 26 , 27 , 28 ]. Four NF membranes have the characteristic peaks of polyamide: Amide I band (1650 cm −1 ), Amide III band (1410 cm −1 ), Amide IV band (690, 714 cm −1 ), O=S=O symmetric stretching peak (1152 cm −1 ), and C=C phenyl group peaks (1585, 1485, 1105 cm −1 ).…”

Sustainable Hydrometallurgical Recovery of Valuable Elements from Spent Nickel–Metal Hydride HEV Batteries

“…In the present study, the separation of REE from the leach liquors by precipitation and an integrated recovery of acid by nanofiltration have been investigated and assessed. Nanofiltration can be applied to recycle used waste pickling acid [35], to separate REE from acid mine drainage and to deal with environmentally problematic wastes [36], to recover nickel [37] and to separate Nd from waste water [38].…”

Study on the Concentration of Acrylic Acid and Acetic Acid by Reverse Osmosis

“…The FT–IR spectra detected in the range of 800–3500 cm −1 were shown in Figure 7 , which contained both the bands of the active layer (PA) and the support layer (polysulfone, PSU) [ 43 ]. Two additional peaks were observed at 3300 cm −1 (NH + and OH − groups) [ 44 ] and 1723 cm −1 (C=O of carboxylic acid) [ 45 ] for the samples C5-2.5 and C6-2.5 after exposure for six months, which may be attributed to the following two factors. Firstly, the oxygen was more electronegative than carbon.…”

“…The atomic percent of C1s (284.8 eV), O1s (531.3 eV), N1s (399.8 eV) and the atomic ratio of C/O, O/N were shown in Table 4 . The atomic percent of carbon and oxygen was increased which of nitrogen was decreased attributed to the absorption of acrylic acid and acetic acid and the hydrolysis of the amide bond [ 44 ]. The atomic ratio of C/O was reduced and that of O/N was increased.…”

“…The corresponding C1s spectra and N1s spectra of the membranes before and after exposure were presented in Supplementary Figures S4 and S5 . There were four peaks of C1s in the results of all samples, which were observed at 284.3 eV (C–C, C–H), 285.1 eV (C–O, C–N), 287.7 eV (C=O, O=C–N), and 290.4 eV (π-π bonds) [ 44 , 48 ]. For nitrogen, the peak at 399.8 eV represented C–N and O=C–N [ 49 ].…”