Effect of particles on copper ion removal using ion exchange membrane without external power input

Key words: 
• Donnan dialysis /
• ion exchange membrane /
• particle /
• copper ions

Abstract: Four particle materials, silicon acid, silicon dioxide, alumina, and salicylic acid were selected and all were dosed at 50 mg/L separately. The concentrations for Cu2+ and its compensating ion, K+, were at 0.0787 mmol/L(5 mg/L)and 0.787 mmol/L, respectively, the water temperature was controlled at 25±1℃, the mixing intensity was set up at 600 r/min, and the hydraulic retention time was 12 h. After 96 h operation under those conditions, the removal efficiency of Cu2+ was 84% when there was no disturbing particle; and the removal efficiency of Cu2+ slightly decreased to 81% when the negatively charged particles (silicon acid) or neutral particles (silicon dioxide and alumina) were present; further, it was found that the removal efficiency of Cu2+ decreased to 79% when positively charged particles (salicylic) were dosed. These results indicate that particles with positive charge imposed more effects on the Cu2+ removal than those with negative or non charge, for the positively charged particles could come to the membrane surface or even enter the membrane and combine with the ionic exchanging groups easier than the other particles, resulting in the Cu2+ removal decreasing more.