The Evaluation of Efficiency of Multi-Walled Carbon Nanotubes in Humic Acid Adsorption in Acidic Conditions From Aqueous Solution

The presence of humic acid in water resources is the most health problems of many communities. In recent years, various methods have been focused on for decreasing or removing humic acid that is in water resources and is one of the Trihalomethanes (THMs) precursors. The aim of this study is investigation the use of Multi-Walled Carbon Nanotubes (MWCNTs) as adsorbent at humic acid adsorption process in acidic conditions from aqueous solution. This experimental study was done in batch system to investigate the effects of Variations such as contact time, humic acid concentration and dose of nanotubes in removal of humic acid. In this study, humic acid concentration was determined during various steps of research using UV-vis spectrophotometer at 254 nm. The Results of this study showed that maximum surface adsorption of humic acid onto multi-walled carbon nanotubes was 31.37 mg/gr and maximum adsorption had occurred at acidic pH (pH = 4). This study also had determined that appropriate time for receiving maximum adsorption of humic acid and equalization state is 3 hours. By increasing the adsorbent dose from 0.04 to 0.08 gr per 100 ml, removal efficiency of humic acid solution with 20 mg/l initial concentration increased from 93.5 to 96.8 %. By decreasing humic acidinitial concentration from 30 to 5 mg/l, removal efficiency increased from 91.5 to 96.9 % at pH=4 after 3 hours. This adsorbent could be effective for removal of humic acid due to small size, large surface area, crystal shape and exclusive network arrangement and consequently very high reactivity and noticeable performance of multi-walled carbon nanotubes as adsorbent in removal of organic pollutants from aqueous solution.