Removal Of Iron Ions Research Articles

Electroosmotic flow behaviour of metal contaminated expansive soil

It is important to study the flow behaviour through soil during electrokinetic extraction of contaminants to understand their removal mechanism. The flow through the expansive soil containing montmorillonite is monitored during laboratory electrokinetic extraction of heavy metal contaminants. The permeability of soil, which increases due to the presence of contaminants, is further enhanced during electrokinetic extraction of contaminants due to osmotic permeability. The variations in flow rates through the soil while the extracting fluid is changed to dilute acetic acid (used to control the increase of pH) and EDTA solution (used to desorb the metal ions from soil) are studied. The trends of removal of contaminants vis-a-vis the changes in the flow through the soil during different phases of electrokinetic extraction are established. Chromium ions are removed by flushing of water through the soil and increased osmotic flow is beneficial. Removal of iron ions is enhanced by induced osmotic flow and desorption of ions by electrokinetic processes.

Adsorption of Iron and Manganese Ions Using Low-Cost Materials as Adsorbents

The removal of toxic metal ions (iron and manganese) from aqueous solution by adsorption was studied. The batch process was used either to remove each metal ion singly or both metals as a multi-component system. The adsorbents used were low-cost materials, viz. palm fruit bunch and maize cob. The adsorption isotherms demonstrated that the adsorbents behaved in a favourable manner towards metal ion adsorption. The adsorption capacities for iron ions on palm fruit bunch and maize cob were in the 57–80% range and for the manganese ion in the 50–79% range for initial concentrations between 1 ppm and 10 ppm. With mixtures of both metal ions, removal of iron ions from the mixture was in the 54–79% range and for the manganese ion in the 54–76% range. The extended Langmuir model gave poor agreement with the data for the adsorption of mixtures of the two metal ions while the P-factor model yielded good agreement.

Shipboard analysis of picomolar levels of manganese in seawater by chelating resin concentration and chemiluminescence detection.

A new shipboard analytical method for determining picomolar levels of manganese in seawater has been developed. The method is based on a combination of chelating resin column extraction and improved chemiluminescence (CL) detection in a closed flow system. In this method, manganese in sample solution is selectively collected on newly-developed iminodiacetate-immobilized chelating resin, and then eluted with acidic solution containing hydrogen peroxide. The resulting eluent is mixed with luminol solution and aqueous ammonia after removal of iron ions by a chelating resin column, and then the mixture is introduced into the CL cell. The manganese concentration is obtained from the CL intensity. The detection limit (3SD) of manganese is 5 pmol L(-1) from 9 mL of seawater sample. The method was applied to seawater samples collected at the Okinawa Trough.

Application of modified polysulfone membranes to the treatment of water solutions containing humic substances and metal ions

The results of ultrafiltration removal of humic substances and metal ion admixtures from aqueous solutions have been presented. The membranes applied were made of sulfonated polysulfone. Transport and separation properties of the membranes in relation to model solutions have been investigated. In the experiments two types of modified polysulfone membranes (of a different amount of sulfonated groups) were applied. Removal of iron and manganese ions as well as co-removal of these ions in the case of solutions containing both metal ions and humic substances were tested. It was found that ultrafiltration membranes made of sulfonated polysulfone can be useful in a highly effective (up to 98%) removal of humic substances from water. It was noticed that the increase of sulfone group content in polymeric matrix limited the occurrence of membrane fouling, which contributed to the increase of effectiveness of the process. Applied membranes allowed an effective removal of iron ions (up to 95%) from solutions also containing humic substances by retention of their metal-organic complexes or co-precipitating metal hydroxides. Manganese ions, which form complexes with humic substances in a very limited amount, were removed in a limited extent (up to 45%).