Development of a HTPB-PMHS stability-enhanced extraction gel membrane for nickel ion recovery

A stability-enhanced extraction gel membrane (EGM) with a thin functional layer of carrier for metal ion recovery was prepared and improved by cross-linking technology. Hydroxyl-terminated polybutadiene (HTPB) was used as the coupling agent to form a cross-linked network skeleton. Polymethylhydrosiloxane (PMHS) and HTPB were hydrosilylated to form a compact cross-linked structure. In addition, the D2EHPA (carrier) was fixed on polymer cross-linked structure. The prepared stability-enhanced EGM was characterized by SEM, EDS, ATR-IR, XPS . The influence of preparation parameters was studied and compared systematically. The optimum preparation conditions obtained from the data indicate that the total polymer concentration is 8 wt%, the mass ratio of HTPB/PMHS is 1:2, and the mass ratio of TEOS/VTES is 1:1. After 72 h of stability experiments, the mass transfer flux decreased from 2065.46 mg m −2  h −1 –1718.82 mg m −2  h −1 , the overall flux attenuation rate is only 16.8 %, which is 50.8 % lower than that of EGM without surface enhancing layer. In comparison, the flux attenuation rate of the traditional supported liquid membrane (SLM) even reached 100 % after 66 h. Therefore, the stability-enhanced EGM prepared in this study presents obviously higher operating stability compared with the EGMs operated at same conditions. The results suggest a potential approach for metal ions removal from water with high efficiency and stability.