Experimental study on nanofiltration separation of high concentrated saline glyphosate solution

To investigate the feasibility of nanofiltration technology to separate glyphosate solution containing high concentration of monovalent salt, a commercial Desal-DK nanofiltration membrane was used to carry out separation experiments and simulation calculations of glyphosate solution containing high concentration of NaCl. Firstly, effects of feed compositions and transmembrane pressures on the flux and the solute retention for single solutions were investigated by the NF filtration experiments. Membrane parameters were obtained by fitting the experimental results to the SK (Spiegler-Kedem) equations. The results showed that the Desal-DK NF membrane had a low rejection to NaCl and a high rejection to glyphosate for the single solutions. For the high-concentrated binary component solutions, volumetric fluxes of the mixed solution is significantly reduced compared to the single solutions, while the NF membrane presented higher retention rate (more than 90%) to glyphosate and a lower rejection (less than 10%) to NaCl. Finally the selective separation of NaCl and glyphosate by NF diafiltration was simulated for the binary solution containing 1 g/L glyphosate and 100 g/L NaCl. After pre-concentration and diafiltration, a highly concentrated solution of glyphosate (7.43 g/L) and a relatively pure solution of NaCl (89.02 g/L) were obtained. This work demonstrated that DK NF membrane is a practical way for the separation of glyphosate and NaCl in the industry. © All Right Reserved.