Investigation of Effective Parameters in Adsorption of Reactive Yellow 145 from Aqueous Solution by Using Activated Carbon Prepared from Rice Straw

Recently, the influx of dyes into water resources has disrupted the natural order of ecologists due to their toxicity to biodiversity. In this study, activated carbon prepared from rice straw was synthesized with potassium hydroxide solution in ratios of 1: 3 and 1: 2 at temperatures of 800 °C and 900 °C, and it was used to absorb reactive yellow 145 dye prepared in a laboratory that has similar properties to the real effluent of Tehran textile industry. Then, the effect of important variables on the adsorption process such as pH (2-8), contact time (15-120 minutes), adsorbent dose (30-60 mg), dye concentration (50-200 mg/L), and temperature (15-45 °C) Checked out. The results showed that the adsorption rate was inversely related to the pH of the solution and the initial dye concentration and was directly related to the adsorbent dose, temperature, and activator saturation ratio. Among the isothermal models, the Redlich-Peterson model (R2 = 0.995) with the equilibrium adsorption capacity of 324.6 mg/g had a better agreement with the experimental adsorption results and the kinetic studies showed that the adsorption process follows the pseudo-second-order model (R2= 0.995). Thermodynamic studies also showed that the adsorption process is spontaneous and the negative slope of the Van-Hoff curve indicates that the reaction is endothermic. Due to the equilibrium time of 60 minutes in the adsorption mechanism, the synthesized adsorbent has a high rate of adsorption of reactive yellow 145 dye. The synthesized adsorbent with properties such as high specific surface area, environmentally friendly, availability of precursors, and suitable performance in dye adsorption can be used effectively in dye effluent treatment systems.