Journal of

Background: One of the most important sources of environmental pollution is dye from industrial wastewater which is harmful for human health and environment. Therefore, the aim of this study was to evaluate removal of Crystal violet (CV) dye from aqueous solutions by citric acid modified barley straw using response surface methodology. Methods: This research was an experimental-laboratory study. The batch experiment was conducted to evaluate the effect of pH, dye concentration, adsorbent dosage, and contact time on dye removal from aqueous solution. Response surface methodology was applied to appraise the effect of these different variables. The dye concentration in the solutions was measured by spectrophotometer at the wavelength of 594 nm. Results: The result of this research showed that dye removal efficiency was increased by increasing of adsorbent dosage, pH, and contact time, whilst decreased by increasing of initial dye concentration. The Maximum and minimum dye removal were obtained 94 and 35 percent, respectively. Analysis of variances test showed that the linear model was the best model to explain the interaction of variables. Conclusion: According to the obtained results, modified barley straw appears to be used as a suitable, low cost, and efficient adsorbent for removal crystal violet dye from aqueous solutions.