RAPID REMOVAL OF HEAVY METAL IONS FROM AQUEOUS SOLUTIONS BY LOW COST ADSORBENTS

Heavy metals are frequently present in the aquatic streams by different industrial wastewaters. The presence of these metals in the environment is of importance concern due to their toxicity and health effects on the human and living creatures. In the present investigation, different agricultural solid wastes namely: eggplant hull, almond green hull, and walnut shell were introduced as low cost adsorbents and used for the removal of heavy metals such as cobalt, strontium and mercury ions from aqueous solutions. Activation process and/or chemical treatments using H2O2 and NH3 were performed on these raw materials to increase their adsorption performances. The effectiveness of these adsorbents was studied in batch adsorption mode under a variety of experimental conditions such as: different chemical treatments, various amounts of adsorbents, initial metal-ion concentrations, pH of solutions, contact times, and solution temperatures. To the best of our knowledge, most of these adsorbents have not been previously used for the removal of mentioned ions from water. High metal adsorption efficiencies were achieved for all cases only in the first 2-3 minutes of adsorbents ’ contact times. The optimum doses of almond green hull adsorbent for th