Bin Jiang,Lele Wang,Jiaxin Na,Xiaoqing Zhang,Yongqiang Yuan,Chunhong Liu,Zhibiao Feng
Aqueous two-phase flotation (ATPF) consisting of 1000 g/mol polyethylene glycol (PEG 1000)/trisodium citrate was developed for the separation of α -Lactalbumin ( α -La) from whey. The flotation efficiency ( E ) and purification factor ( PF ) of α -La were evaluated using the reversed-phase high-performance liquid chromatography (RP-HPLC). The effects of pH, concentration of trisodium citrate, flow velocity, flotation time and whey loading on the E and PF of α -La were investigated. An efficient separation of α -La from whey was achieved using ATPF with pH of 8.20, 5 mL of 0.50 g/mL PEG 1000 solution, 35 mL of 0.40 g/mL trisodium citrate solution and whey (20%, v/v), 30 mL/min of flow velocity and 42 min of flotation time. Under the optimal conditions, E and PF of α -La could reach 87.54% and 5.33, respectively. In addition, the kinetic process of the separation of α -La by ATPF of PEG 1000/trisodium citrate was investigated. The results showed that there were two stages in the separation process. Both stages obeyed the first-order kinetic equation, and the first stage was faster than the second one.
Wenjuan Wang,Wenting Li,Jiaqi Shi,Saeed Ahmed Memon,Yun Wei
Rare earth elements are non-renewable resources. During their processing, a lot of wastewater are produced, which poses a danger to human beings and the environment. Herein, the enrichment method of solvent sublation for La (III), Ce (III), Gd (III) and Er (III) was designed and established. Enrichment parameters pH, flotation time, extractant concentration and air flow rate were optimized. The result showed that the highest recovery of La (III) reached up to 92.33 % under the optimized conditions of pH 8, 10 min of flotation time, 0.15 mol L -1 of the extractant 2-ethylhexyl phosphate acid-2-ethylhexyl ester and 30 mL min −1 of air flow rate. The light rare earth element Ce (III) and heavy rare earth elements Gd (III) and Er (III) were also examined and obtained with maximum recovery. The stability of the extractant complexation with rare earth ions and the mechanism of competitive extraction were studied by density functional theory calculations. The extraction ability was following sequence of La (III) < Ce (III) < Gd (III) < Er (III). The enrichment of rare earth elements from real water samples was investigated and obtained result was consistent with the experiment result of synthetic solutions. The established high speed countercurrent chromatography method was used to successfully separate La (III), Ce (III), Gd (III) and Er (III) from the solution of rare earth ions enriched by solvent sublation.
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