Efficient separation of boron from salt lake brine using a novel flotation agent synthesized from NMDG and 1-bromooctadecane

A novel flotation agent named N-octadecyl-N-methyl-D-glucamine (NO-NMDG), was designed and prepared using N-methyl-D-glucamine as a polyhydroxy molecule and 1-bromooctadecane as the provider of a long-chain alkyl group. The results of characterization by NMR, MS and FT-IR showed that the target compound was successfully synthesized. NO-NMDG can effectively separate boron from aqueous solutions because of its complexing ability for boron and its foamability. The flotation experiments results showed that the flotation isotherm was in better accordance with the Langmuir model, indicating that the surface reaction in flotation by NO-NMDG belongs to the single molecular layer trapping. The response surface experimental results indicated that under the optimum conditions, the boron recovery rate can reach to 89.12%. The boron recovery rate in Xiao Chaidan brine could reach to 97.26% by NO-NMDG. The mechanism analysis exhibited that the meglumine group in NO-NMDG can complex with boron, and the long-chain alkyl group can attach to the surface of the bubble and enter into the bubble layer to separate boron from the aqueous solution.