Introduction: The dyestuff manufacturing and textile industries consume a high volume of water and produce a great amount of wastewater containing various toxic substances. This study was conducted to evaluate the possibility of using activated carbon prepared from milk vetch wood for removing methylene blue dye from synthetic wastewater.

Materials & methods: This research was carried out in laboratory scale with using of 100 ml volume of batch photoreactor and in chemistry laboratory of Ilam university of medical sciences (summer 2013). Activated carbon was prepared using chemical-thermal method. The effect of pH, contact time, dye concentration and adsorbent dosage on the adsorption of methylene blue dye as model organic dye was studied and kinetic and isotherm of the adsorption process was investigated. The dye concentrations were measured via spectrophotometer (665 nm wavelength). 

Findings: The results showed that activated carbon prepared from milk vetch has high potential to remove dye molecules. The MB absorption capacity rates were 38.66, 40 and 48.5 mg/g respectively at pH of 3, 7 and 11 for the initial dye concentration of 50 mg/L and 0.1 g/0.1L absorbent mass  at 30 minute. Also dye absorption rates were 40, 69.66, and 78.04 mg/g on absorbent respectively for 50, 100, and 150 mg/l dye concentration, at pH of 7, 1 g/0.1L absorbent mass, and 30 minutes time. Adsorption data followed Langmuir isotherm model (R²=0.99). 

Discussion & conclusion:  Based on the obtained results, activated carbon prepared from milk vetch can be considered as an efficient adsorbent for removing dye from aqueous phase.