Ultrafiltration membrane for effective removal of chromium ions from potable water

Abstract

The objective of the present work was to investigate the efficacy of indigenously developed polyacrylonitrile (PAN) based ultrafiltration (UF) membrane for chromium ions removal from potable water. The hydrolyzed PAN membranes effectively rejected chromium anions in the feed ranging from 250 ppb to 400 ppm and a rejection of ≥90% was achieved for pH ≥ 7 at low chromate concentration (≤25 ppm) in feed. The rejection mechanism of chromium ions was strongly dependent on Donnan exclusion principle, while size exclusion principle for UF did not play a major role on ions rejection. Feed pH played a vital role in changing porosity of membrane, which influenced the retention behavior of chromate ions. Cross-flow velocity, pressure did not play significant role for ions rejection at low feed concentration. However, at higher feed concentration (≥400 ppm), concentration polarization became important and it reduced the chromate rejection to 32% at low cross flow and high pressure. Donnan steric-partitioning pore and dielectric exclusion model (DSPM-DE) was applied to evaluate the chromate ions transport through PAN UF membrane as a function of flux by using optimized model parameters and the simulated data matched well with experimental results.

Ingestible Osmotic Pill for In Vivo Sampling of Gut Microbiomes

“…We believe this is because the pH protonates and deprotonates the functional groups of the membrane itself and of the molecules in solution. This effect will change the effective charge on the membrane and alter the size of the pores, which will impact the membrane's nanofiltration properties and affect the flux of water . The zeta potential (ζ) of a cellulose acetate membrane is negative for pH 3 or higher and becomes more negative as the pH increases .…”

Effect of temperature on ion transport in nanofiltration membranes: Diffusion, convection and electromigration

“…Furthermore, the image charges are screened by electric double layers in electrolyte solutions [21]. The DSPM-DE model in the form introduced by Bowen and Welfoot [21] has been used successfully by several authors, including in recent years for a variety of feed compositions [16] [18] [19]. In reference [21], Bowen and Welfoot successfully implemented the DSPM-DE model for the same membrane considered in the current work (Desal5DK) accounting for only the Born mechanism of dielectric exclusion for sodium-chloride and magnesium-chloride.…”

“…This model has been used widely into recent times to model and explain nanofiltration performance using a variety of feed solutions with success [14] [15] [16] [17] [18] [19]. DSPM-DE is a comprehensive model for nanofiltration.…”

Reduction of Hexavalent Chromium Using Sorbaria sorbifolia Aqueous Leaf Extract

“…Many remediation strategies have been advanced to deal with Cr(VI) pollution, including adsorption [6], ion exchange [7], chemical precipitation [8], membrane filtration [9] and reduction [10][11][12][13][14][15][16][17], among others. The reduction of Cr(VI) is among the most widely used strategies in view of the redox activity of chromium.…”