Boron removal from aqueous solutions via polymer enhanced ultrafiltration using novel Imino-bis-propane diol functional polymers

Zerze, Hasan
In this work, newly synthesized poly (vinyl amino-N, N’-bis-propane diol) (GPVA) and copolymer, poly (vinyl amino-N, N’-bis-propane diol-co-DADMAC) (GPVA-co-DADMAC) were efficiently exploited for boron removal via polymer enhanced ultrafiltration (PEUF). Boron concentration could be reduced from 10ppm down to 0.4ppm using GPVA whereas it could be reduced from 10ppm down to 0.8ppm with copolymer GPVA-co-DADMAC at pH 9 and loading (boron-to-polymer mass ratio) 0.001 via continuous polymer enhanced ultrafiltration (PEUF). Experiments revealed that GPVA shows the highest PEUF boron retentions (96% at pH 9.0) reported so far, without precipitation in a wide concentration range. Detailed investigations such as effect of pH, loading and polymer concentration showed that, the boron binding is highly pH dependent and increases with polymer concentration at constant loading for all the synthesized polymers. Furthermore, permeate flux was found as nearly independent of polymer concentration within the range of parameters studied (polymer concentration≤10g/L; pressure drop: 200kPa). High pH and concentration dependency of boron binding makes it possible to have polymer regeneration and boron recovery. In addition, gyration radius of GPVA in solution increases with increasing pH and polymer concentration in the presence of boron as inferred from Dynamic and Static Light Scattering measurements. Furthermore, a two-step equilibrium model was correlated with the experimental boron retention data, to explain the compexation behavior of polymer. Regarding with high efficiency and hydrolytic stability of the synthesized polymers, their use in combination with PEUF would be of interest for large scale and long term use in boron removal.