Efficiency Evaluation of Natural (Crude) and Citric Acid Modified Rice Straw for Removal of Pb from Aqueous Solutions

Background and Up to now various methods has been considered for removing heavy metals such as pb from aqueous solution including using agricultural wastes as low cost adsorbent. The purpose of this study was efficiency evaluation of natural (crude) and citric acid modified rice straw for removal of pb from aqueous solutions. This study was performed at laboratory scale and batch system. We studied the influence of process variables such as pH, contact time, pb concentration and adsorbent dosage. Data from equilibrium study were modeled using isotherm and kinetic models. The concentration of pb was measured by atomic adsorption. Data was then analyzed using ANOVA test. Experimental results showed that the optimum pH and equilibrium time for pb by natural and modified rice straw was 6 and 120 minute, respectively. Removal of pb increased in both adsorbent dosages by increase in pb concentration up to 10 mg/l and increasing the dosage of adsorbents. Adsorption isotherm fitted Temkin model but adsorption kinetic followed pseudo second order. The efficiency of natural rice straw and modified rice straw in removal of pb was 85 and 99%, respectively. According to the results, rice straw especially the modified one could be used as a suitable, low cost and efficient adsorbent for removal of pb from aqueous solutions.