Adsorption of Bisphenol from Industrial Wastewater by Modified Red Mud

Bisphenol A، a toxic environmental pollutant released from industries، can be dangerous even at low concentrations. The aim of this study was to investigate the adsorption of bisphenol by red mud modified with nitric acid. Red mud was modified with nitric acid and washed with distilled water. It was then dried at 103ºC for six hours and seived (mesh size: 100). The optimum equilibrium time was determined in various bisphenol concentrations and doses of adsorbent. The optimum amount of bisphenol، dose of adsorbent، and pH were calculated by keeping the optimum equilibrium time constant. Isotherms and kentic relations were determined by using equiliberium data. Increasing contact time and dose of adsorbent enhanced the adsorption of bisphenol. To be more precise، increasing contact time from 10 to 210 minutes increased the adsorption from 43% to 84%. Increasing adsorbent dosage from 2 to 20 g/l increased adsorption from 40% to 80%. Adsorption was also promoted by decreasing the initial concentration of bisphenol. The best pH for bisphenol removal was 3. The adsorption data was best fitted to the Freundlich isotherm and pseudo-second order kinetic model. Red mud is a waste product from the industrial processing of aluminum. According to our findings، it can be used as an effective، low-cost، and available adsorbent to remove bisphenol from industrial wastewater.