title: Utilization of activated CO2-neutralized red mud for removal of arsenate from aqueous solutions.
abstract: A laboratory study was conducted to investigate the ability of activated CO(2)-neutralized red mud (ANRM) for the removal of arsenate from the aqueous solutions. The batch adsorption experiments were conducted with respect to adsorbent dose, equilibrium pH, contact time, initial arsenate concentration, kinetics, Langmuir isotherms. The mechanisms involved in adsorption of arsenate ions on ANRM were characterized by using XRD, FT-IR, UV-vis, SEM/EDX, and chemical methods. The percentage removal was found to increase gradually with decrease of pH and maximum removal was achieved at pH approximately 4. Adsorption kinetic studies revealed that the adsorption process followed pseudo-second-order kinetics and equilibrates within 24 h. FT-IR spectra of ANRM before and after adsorption reveals the binding of arsenate to the adsorbent. The adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient)>0.99. Arsenate adsorbed ANRM can be regenerated using NaOH solution at pH 12.0.
authors.affiliation: Department of Chemistry, National Institute of Technology, Rourkela 769008, Orissa, India. rcsahu.chem@gmail.com
authors.forename: Ramesh Chandra
authors.initials: RC
authors.lastname: Sahu
authors.forename: Rajkishore
authors.initials: R
authors.lastname: Patel
authors.forename: Bankim Chandra
authors.initials: BC
authors.lastname: Ray
mesh_terms: D000327:Adsorption; D000465:Algorithms; D000537:Aluminum Oxide / Q000737:chemistry*; D001149:Arsenates / Q000302:isolation & purification*; D002245:Carbon Dioxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D009584:Nitrogen / Q000032:analysis; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D014961:X-Ray Diffraction
chemical_list: D001149:Arsenates; D007220:Industrial Waste; D012996:Solutions; D014874:Water Pollutants, Chemical; D002245:Carbon Dioxide; D000537:Aluminum Oxide; D009584:Nitrogen; C025657:arsenic acid