Wood-fibrous sorbents for purification of effluent from heavy metals

Abstract

Pollution of the water sources by heavy metals is a great problem on a world scale. Heavy metals are one of the most dangerous polluters of waste and surface waters used for irrigation. At many industrial processes effluent consists of high concentration of toxic heavy metal ions – copper, zinc, lead, cadmium, aluminum, iron, magnesium, chromium, cobalt etc. At present time these polluters have been removed by different methods. Chemical precipitation, extraction by solvents, dialysis or electro-dialysis, electrolytic extraction, evaporation methods, ion-exchange pitches, adsorption on charcoal etc. have been used. In most cases the results of different methods of chemical precipitation do not satisfy the requirements in the accepted international standards. For the moment alkaline precipitation is the cheapest and widespread method for purification of industrial waters. However, by this method the amount of unwanted polluted precipitation is high. Ion-exchange is efficient at purification of solutions from metal ions, but the synthetic pitches used for that are too expensive. Adsorption can be used as one economical and acceptable method for removal even of traces of metal ions from solutions.