Model assessment of a nanofiltration membrane for the removal metal ions from simulated wastewater

O Agboola,S.E Sanni,E.R Sadiku,A Kolesnikov,R Mbaya,J.P Maree

doi:10.1088/1742-6596/1378/3/032048

Abstract

This paper accords the likelihood of applying Donnan and Steric Partitioning Pore Model (DSPM) together with extended Nernst-Planck model to elucidate the capacity of charge and Donnan exclusion mechanisms in removing ions from simulated wastewater in Nano-Pro-3012 membrane filtration process. The extended Nernst-Planck model reports the transportation of cations across Nano-Pro-3012 with respect to electrical potential gradient, movement of solutes and pressure difference through the membrane. The working principle of these two equations is dependent on the adsorption of the charged surface, diffusion and convective transport. This principle was established with a software called Comsol multi-physic 4.3b to explain the capacity of charge and Donnan exclusion mechanism of Nano-Pro-3012. The extended Nernst-Planck model and the Darcy law model were applied to evaluate the physical interrelationship amidst NanoPro-3012 and ionic solutions with the aim of having a good understanding of the transport and rejection working operation of the ions. The principle of these equations was first used to envisage the capability of Nano-Pro-3012. The data obtained were validated with the laboratory data. There was an establishment that movement of solutes across the membrane bring about diffusion transport. The total flux in solution increases due to the working operation of the diffusion which in turns reduces the electrical potential, as a result, reduces the flux in the membrane. Ions smaller than pore sizes are rejected and the theoretical data is in conformity with the experimental data.

Highlights

The obtainability of clean water has come to be a serious global challenge confronting the mankind as a result of water contamination by human activities [1]
Extended Nernst-Planck model illustrates the diffusion, convection, and electro-migration triggered by electrical potential and concentration gradients [22]
Concentration gradient through the membrane result in diffusion transport. This upsurges the entire flux in solution and decreases the electrical potential; in so doing reduces the flux in the membrane

Summary

Introduction

The obtainability of clean water has come to be a serious global challenge confronting the mankind as a result of water contamination by human activities [1]. Nernst-Planck model for the movement of ions, the Navier-Stokes model for volumetric flow and the Poisson-Boltzmann model for radially circulation of the electric potential together with ion concentration are considered fundamental equations that governs the mechanism of the space charge theory [11]. Extended Nernst-Planck model illustrates the diffusion, convection, and electro-migration triggered by electrical potential and concentration gradients [22]. Following the work of [27], the separation principle of ion linking membrane and solution at the circumferences of the membranes (feed part and infiltrate part) was described by the steric-Donnan equilibrium. The ion concentrations in the feed and infiltrate do not independently satisfy the condition of electro-neutrality from the membrane charge; Nernst Planck model in the absence of electro-neutrality must be applied [27]. The instrument was equipped with a water crossflow nebuliser and a Scott double-pass spray chamber

The motion of ion through the membrane

Conclusion