Cu2+ tunable temperature-responsive Pickering foams stabilized by poly (N-isopropylacrylamide-co-vinyl imidazole) microgel: Significance for Cu2+ recovery via flotation

Froth flotation has been a key chemical process extensively used in the recovery of heavy metal ions (e.g. Cu2+) from contaminated water, while often criticized by secondary pollution added collectors, and less selectivity to specific since ion removal particles is independent post-step particle flotation. To facilitate industrial operation, “smart” with foams responsively stabilized after selective adsorption target competitive are highly desired. In current study, Cu2+ responsive microgels were presented as proof-of-concept. Firstly, Cu2+-responsive thermo-sensitive poly (N-Isopropylacrylamide-co-Vinyl imidazole) (PNV) microgel hydrodynamic radius (Rh) ? 334 nm fuzziness 37.2 was synthesized. Cu2+-imidazole complexation demonstrated enhance swelling softer more homogenous microstructure, having Rh increased 30–50 for 0.005 M 0.25 significant volume phase transition temperature (VPTT) shift 40 °C 50 Cu2+, ?60 0.05 ? 60 Cu2+. Secondly, ultra-stability below VPTT rapid collapse above readily produced based on PNV microgels. enabled modulation responsiveness foams, able maintain good foam stability high temperatures life time > 6 h at 45 where rapidly collapsed other cations 2 min, ?10 min 15 Na+, Mg2+, Zn2+, respectively), showing significance via Furthermore, an interfacial study air–water interface revealed better surface activity -complexed dependence. An abrupt reduction rheology around G’s(25 °C)/G’s(70 °C) ratio 300.1 observed believed be main reason destabilization PNV2, which avoidable entanglements between Cu2+-complexed microgels, giving 1.68. Ultimately, PNV2 well mixed solutions Zn2+ terms sorption, stabillity. This Pickering tunable microgel, laying foundations develop microgel-based smart green technology recovery.