Abstract
Background and purpose: Dyes are a group of organic substances with a complex structure, often toxic, carcinogenic, mutagenic, non-biodegradable, and one of the most important pollutants in textile and dyeing industries' waste water, whose discharge in the environment creates severe problems. There are different methods for separating colors from wastewater, and the absorption process is one of the methods that has attracted a lot of attention in recent years, and a lot of research has been done in the field of searching for cheap and effective adsorbents in absorbing all kinds of colors. In this study, the ability of cotton activated carbon to absorb acid orange 7 has been evaluated.
Materials: In this experimental study, the required cotton was procured from Gonabad city and placed in an electric furnace at a temperature of 550 degrees Celsius for 2 hours for carbonization. Then, the effect of adsorbent dose, pH, contact time and dye concentration variables on dye removal efficiency from synthetic aqueous solutions at ambient temperature (27°C) was investigated.

Results: The results of the experiments showed that by increasing the adsorbent dose, decreasing the pH, increasing the contact time and decreasing the initial concentration of the dye, the absorption process improves. According to the findings of this study, the maximum removal efficiency, equivalent to 87%, was obtained in optimal conditions in the amount of 1 gram/liter of absorbent, pH=2, initial dye concentration of 5 mg/liter, and contact time of 80 minutes.

Conclusion: The results showed that the activated carbon obtained from cotton can be used as an efficiecnt, cheap and available adsornebt for the removal of  Acid Orange 7 from aqueous solutions.