Dual 3-D networked Pickering emulsion hydrogels encapsulating copper extractants for the recovery of Cu2+ from water

Abstract

Conventional emulsion hydrogel adsorbents for recovering metal ions from water were commonly limited by their extractant leakage and relatively low encapsulation efficiency. In this work, dual 3-D networked Pickering emulsion hydrogels (PEHGs) encapsulating copper ion extractant N902 were prepared by polymerizing an oil-in-water Pickering emulsion. The PEHGs were characterized by SEM, TGA and compressing tests. Static and fixed-bed experiments of the PEHGs for the adsorption of Cu2+ were carried out. The results showed that the encapsulation efficiency of extractants reached 99% and the leakage of extractants was negligible owing to the 3-D hydrogel networks and the 3-D silica nanoparticle networks in PEHGs. The critical crashing pressure of PEHGs (oil fraction was 40% v/v) was 30.08 kPa with a deformation ratio of 0.7. The saturated extraction capacity of the extractants in PEHGs was higher than that of bare extractants. The adsorption capacity of Cu2+ on fixed-bed (10.12 mg g−1) was consistent with the predicted value of Langmuir isotherm model. After 65 cycles, the amount of Cu2+ adsorbed onto PEHGs maintained 97.5% of the initial one without extractant leakage and mass loss. Due to the well protection of extractants, this adsorbent encapsulating extractants presented a promising potential application for water treatment.