Zinc removal from wastewater by a complexation-microfiltration process

Abstract

Due to its wide industrial applications, zinc has become an important contaminant in aquatic environments since it is a toxic heavy metal and some of its compounds, such as zinc arsenate and zinc cyanide, may be extremely hazardous. Therefore, there is a growing need to develop simple methods capable of separating and recovering trace zinc from environmental waters. Nowadays, ultra- and microfiltration methods for trace metals removal from waters by the addition of a water-soluble polymer into the aqueous solutions have become a significant area of research. The choice of water-soluble macroligands remains important for the development of this technology. Sodium carboxymethyl cellulose (Na-CMC) was selected as the complexing agent. The microfiltration experiments were performed in a stirred dead-end cell. Versapor membranes were used to separate the formed polymer-metal complex. The concentration of heavy metal ions after microfiltration in aqueous solution was determined using atomic absorption spectroscopy (AAS). The effects of the amount of complexing agent, pH value, type of anion, ionic strength and operating pressure on the flux (J) and rejection coefficient (R) were investigated. Experimental results indicate a considerable influence of the pH, ionic strength and type of anion on the rejection coefficient, while the effect of the amount of the complexing agent was relatively insignificant. The Na-CMC used in the research proved very effective, which is supported by the high rejection coefficients obtained (99 %). Copyright © 2012 (CC) SCS.