Comparison the removal of reactive red 195 dye using powder and ash of barberry stem as a low cost adsorbent from aqueous solutions: Isotherm and kinetic study

Dyes are used in various sectors, such as the textile, leather, paper, and plastic industries, and a significant part of this dye enters the environment via wastewaters. The present research was a laboratory-scale study with the aim of investigating the effective parameters in the dye-removal process, including pH (3−11), contact time (5-120 min), dye concentration (10-50 mg/l), adsorbent dose (1-4 g/l), and temperature (15-35 °C). The maximum adsorption capacity was observed at pH = 3, contact time = 10 min, initial dye concentration = 50 mg/l, adsorbent dose = 1 g/l, and temperature = 15 °C. With these parameters, the maximum adsorption capacities for barberry stem powder and ash were 27.2 mg/g and 8.8 mg/g, respectively. The results of examining the adsorption isotherms showed that the barberry powder followed from both the Langmuir (0.94) and Freundlich (0.94) isotherms, while barberry stem ash followed from the Freundlich (0.85) isotherm. Kinetic adsorption studies showed that the dye adsorption on both adsorbents followed a pseudo-second-order kinetics. The results showed that the barberry stem powder and ash had desirable capacity in reactive red 195 (RR195) dye from aqueous solutions and textile wastewaters.