removal of arsenic from aqueous solutions using welding iron waste

background: contamination of water with arsenic has attracted the researchers’ attention as a global problem in recent years and has been observed in some parts of iran. the purpose of this study is to assess the efficiency of welding iron waste in removing arsenic from aqueous solutions.   methods: in this study, the effects of different parameters, such as ph (3-9), initial concentration of arsenic (100-3000 μg/l), contact time (5-90min) and adsorbent dose (2.5-20 g/l), were studied. the final concentrations of arsenic were analyzed by atomic absorption.   results: the results indicated that at ph=3 and fixed dose of 1 g, arsenic removal efficiency of iron waste was 89.73%. by increasing the ph to 7, the removal efficiency increased to 96.44%. also, an increase in the amount of iron waste from 2.5 to 10g/l, the removal rate increased from about 42.37% to 96.70%. for contact times of 5 and 30 minutes, the removal rate was 9% and 96.62%, respectively. then, with increasing the contact time to 90 minutes, the removal rate increased to 99.24%. correlation coefficient of freundlich and langmuir isotherms for as(iii) was 0.7593 and 0.9979, respectively .   conclusion: the results of the study showed that welding iron waste has a high potential as an effective, fast and cheap method for removal of arsenate and arsenite from aqueous solutions.