AAS determination of Co(II), Mn(II), Cr(III) and Zn(II) after their solid phase extraction

The contamination of water by heavy metals through the discharge of industrial wastewater is a worldwide environmental problem. Removal of heavy metal ions from wastewater in an effective manner has become an important issue today. In this study, natural bentonite, dolomite, sepiolite and synthetic zeolite clay minerals were used as an adsorbent for the removal of Co(II), Mn(II), Cr(III) and Zn(II) ions from aqueous solution and their determination by flame atomic absorption spectrophotometer is described. A batch and column method were used in all adsorption and recovery experiments. The optimum conditions were determined in the batch method as the amount of adsorbent was from 0,05 g to 0,4 g, pH range between 1 and 8, contact time between 5 and 60 min, and concentration range was between 5 and 100 mg/L. The optimum conditions were found to be a concentration of 10 mg/L, contact time of 30 min and 0,2 g of adsorbent for a quantitative adsorption of the metals. In column method, modified dolomite and sepiolite were used as a solid phase extractant has been developed for the preconcentration of Co(II) and Mn(II) ions. Effects of the analytical conditions over the preconcentration of the metal ions, such as pH, flow rate, eluent type, sample volume and foreign ions have been investigated. The analytes were adsorbed quantitavely even at a flow rate of 1 mL/min at pH 4. Adsorbed metals were eluted using 15 mL of 1 M HCl and HNO3 in acetone. Sorption data have been interpreted in terms of Langmuir and Freundlich equations. In conclusion, as low cost adsorbents can preferable for removal of heavy metals from wastewater. The other main advantages of the method include simplicity, time saving, no requirements of sophisticated instruments, and cost effectiveness.