Rapid removal of heavy metal ions from aqueous solutions by low cost adsorbents

Abstract

In the present investigation, different agricultural solid wastes<br><br>namely: eggplant hull (EH), almond green hull (AGH), and walnut shell (WS),<br><br>that are introduced as low cost adsorbents, were used for the removal of heavy<br><br>metals (cobalt, strontium and mercury ions) from aqueous solutions. Activation<br><br>process and/or chemical treatments using H2O2 and NH3 were performed<br><br>on these raw materials to increase their adsorption performances. The<br><br>effectiveness of these adsorbents was studied in batch adsorption mode under a<br><br>variety of experimental conditions such as: different chemical treatments,<br><br>various amounts of adsorbents, initial metal-ion concentrations, pH of<br><br>solutions, contact times, and solution temperatures. High metal adsorption<br><br>efficiencies were achieved for all cases only in the first two to three minutes of<br><br>adsorbents’ contact time.<br><br>Maximum adsorption capacity of AGH sorbent for cobalt and EH for<br><br>mercury were found to be 45.5 mg/g and 147.06 mg/g, respectively. The<br><br>adsorption capacity of mercury for WS was also obtained as 151.5 and 100.9<br><br>mg/g for two different treated sorbents.