Effect of pH on Total Volume Membrane Charge Density in the Nanofiltration of Aqueous Solutions of Nitrate Salts of Heavy Metals.

Agata Marecka-Migacz,Waldemar Szaferski,Piotr Tomasz Mitkowski,Arkadiusz Nędzarek,Jacek Różański

doi:10.3390/membranes10090235

Agata Marecka-Migacz, Waldemar Szaferski + Show 3 more

Open Access

https://doi.org/10.3390/membranes10090235

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Abstract

The separation efficiencies of aqueous solutions containing nitric salts of Zn, Cu, Fe or Pb at various pH in process of nanofiltration have been investigated experimentally. These results were used to obtain the total volume membrane charge densities, through mathematical modelling based on the Donnan–Steric partitioning Model. The experimentally obtained retention values of individual heavy metal ions varied between 36% (Zn2+ at pH = 2), 57% (Pb2+ at pH = 2), 80% (Fe3+ at pH = 9), and up to 97% (Cu2+ at pH = 9). The mathematical modelling allowed for fitting the total volume membrane charge density (Xd), which yielded values ranging from −451.90 to +900.16 mol/m3 for different non-symmetric ions. This study presents the application of nanofiltration (NF) modelling, including a consideration of each ion present in the NF system—even those originating from solutions used to adjust the pH values of the feed.

Highlights

Nowadays, dynamically thriving chemical plants produce high volumes of wastewaters, and, in many cases, they are a source of polluted water containing heavy metals
The origins of pollution with heavy metals are various; the sources can be related to the corrosion of household plumbing systems, the erosion of natural deposits across liquid industrial wastes in ore enrichment plants, inorganic paint factories, production involving galvanization, etc
Current knowledge indicates that it is better to prevent than combat the effects; recent research has been directed towards methods of preventing the migration of heavy metals from industrial wastewaters to the environment at the source, rather than through their treatment later on

Summary

Introduction

Dynamically thriving chemical plants produce high volumes of wastewaters, and, in many cases, they are a source of polluted water containing heavy metals. The origins of pollution with heavy metals are various; the sources can be related to the corrosion of household plumbing systems, the erosion of natural deposits across liquid industrial wastes in ore enrichment plants, inorganic paint factories, production involving galvanization, etc. The removal of heavy metals from inorganic effluents can be achieved by conventional treatment processes, such as chemical precipitation, flotation, ion exchange and electrochemical deposition.

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