Removal of Heavy Metal Ions (Lead and Arsenic) from Aqueous Solution by Modified Nano-Bentonite

In this paper، the removal of heavy metals، arsenic and lead by modified nano-bentonite (coated with chitosan and carboxymethyl chitosan) has been studied. First، efficiency of removal of heavy metals، arsenic and lead، under the conditions fixed by nano-bentonite and modified nano-bentonite were compared. Following، Effective parameters such as pH، dose of the nano-adsorbent، contact time and initial concentration of lead and arsenic were studied. To determine the optimal parameters and to achieve the highest level of removal، experimental design method was used. Based on the results obtained، nano-bentonite chitosan was found to be more effective for the removal of Pb and As. Also results shows that pH has an effective result on lead removal and also pH and adsorbent dosage has an effective result on arsenic removal. also، according to the results obtained under the optimal conditions: pH=6، contact time of 30 min، the initial concentration of 1000 ppb and dose of adsorbent= 1. 2 g/l for lead، pH=4، contact time of 30 min، the initial concentration of 1000 ppb and dose of adsorbent= 1. 8 g/l for arsenic، the highest value of lead and arsenic removal 92. 50% and 94. 63%، respectively by Nano-bentonite chitosan is achieved.