•A novel sandwich membrane system was proposed.•Simultaneous separation of Cu, Ni and Co in ammoniacal media was achieved.•Over 99.5% of Co, 98.0% of Ni, and 98.9% of Cu distribute in three different rooms.•Only one kind of extractant of M5640 was used in the separation process.In this paper, a new strategy based on a supported liquid membrane (SLM) system for the simultaneous and selective separation of copper, cobalt, and nickel in ammonia/ammonium chloride solutions, using a two-membrane-three-compartment cell (sandwich SLM) was proposed. This model used two polyvinylidene difluoride (PVDF) membranes both loaded with 20 vol.% Acorga M5640 in kerosene. The effects of H2SO4 concentrations in two stripping phases on the transport of copper, nickel, and cobalt were evaluated. Experimental results indicated that copper and nickel were transported through the first membrane into the central compartment which contained 5.0 g/L H2SO4, while cobalt remained in the first feed compartment. Then copper continued to penetrate through the second membrane into the third compartment which contained 50.0 g/L H2SO4, while nickel remained in the second compartment. More than 99.5% of cobalt, 98.0% of nickel, and 98.9% of copper were separated into the three different compartments from a mixed feed solution containing 100 mg/L each of these three species with a transport time of 36 h. A maximum copper flux of 1.59 × 10−6 mol/m2·s was obtained. The results establish that copper, nickel, and cobalt in ammonia solution can be efficiently separated by this novel type of sandwich SLM.

Separation of Ni2+ from ammonia/ammonium chloride solution using a flat-sheet supported liquid membrane (SLM) impregnated with Acorga M5640 in kerosene was investigated. The fundamental experimental variables influencing Ni2+ transport, such as ammonia concentration, carrier concentration, H2SO4 concentration in the stripping solution, stirring speed, and initial Ni2+ concentration were studied. Almost all of Ni2+ was transported from the feed to the stripping phase after 18 h of operation with a permeability coefficient of 9.28 × 10−6 m s−1 under optimum conditions: stirring speed of 1000 rpm in both phases, 20 vol.% Acorga M5640 as the carrier, 1.70 mmol L−1 Ni2+ in the feed phase and 0.10 mol L−1 H2SO4 in the stripping phase. The flux value of Ni2+ was 15.82 × 10−6 mol m−2 s−1. Additionally, the influences of temperature and ultrasound on flux were examined, and results indicated that higher temperature and ultrasonic assistance improved transport of Ni2+ through the SLM. Selective separation of nickel from cobalt in an ammonia/ammonium chloride solution was also achieved through SLM. The stability of the SLM was examined on a continuous run mode and satisfactory stability of the nickel permeation was observed for 84 h (7 runs).

•A novel strategy for selective separation of Cu from Ni in ammoniacal media by SLM.•M5640 and TRPO exhibit antagonistic effects in SLM on transport of Cu and Ni.•Efficient separation of Cu and Ni based on different antagonistic effect on metals.•Over 98.4% of Cu and less than 6.1% of Ni were transported in 12 h.•Satisfactory stability of Cu transport is achieved for 7 days of operation.This paper addresses the simultaneous separation of copper and nickel from ammoniacal/ammonium chloride solutions using supported liquid membrane containing synergistic mixture of Acorga M5640 and trialkyphosphine oxide (TRPO) as carriers. A number of influencing parameters on the Cu(II) transport and separation of Cu(II) from Ni(II) were studied. The results indicate that the mixture of both carriers (TRPO + Acorga M5640) induces antagonistic effects in the SLM system on the transport of Cu(II) and especially the Ni(II). The difference in strength of the antagonistic effect allows the selective separation of copper over nickel from ammoniacal solutions. The metal ions, Cu(II) and Ni(II), were efficiently separated with a factor 16.0 when the following conditions are employed: stirring speed of 1000 rpm in both phases, carrier concentration of (10 vol.% TRPO + 20 vol.% Acorga M5640) in a kerosene based diluent, metal concentrations of 100 mg/L for each of the copper and nickel dissolved in 2.0 mol/L total ammoniacal feed solution, and 50 g/L H2SO4 as a stripping solution. Under the optimal conditions, up to 98.4% of the Cu(II) is transported from the feed phase to the stripping phase within a period of 12 h with a permeation coefficient of 1.21 × 10−5 m/s. At the same time, less than 6.1% of nickel is transported, suggesting a substantial selectivity in the transport phenomena of both metals. The membrane stability of the SLM system was also evaluated and shown to be satisfactory for at least fourteen runs (7 days of continuous operation).Download high-res image (177KB)Download full-size image

A facile generic environmental strategy is employed to prepare hierarchical yolk–shell hybrid NiO@C materials viz. metal–organic frameworks. The intrinsic yolk–shell nature as well as the multi-element characteristics of active components of the unique nanostructures contributes greatly to the outstanding electrochemical performance.

A facile generic environmental strategy is employed to prepare hierarchical yolk–shell hybrid NiO@C materials viz. metal–organic frameworks. The intrinsic yolk–shell nature as well as the multi-element characteristics of active components of the unique nanostructures contributes greatly to the outstanding electrochemical performance.