title: Effect of Ni2+ ion doping on the physical characteristics and chromate adsorption behavior of goethite.
abstract: Pure and 0.25% Ni(2+) ion doped goethite samples, prepared by the coprecipitation method, were characterized for pH of Point of Zero Charge (pH(pzc)), Surface area, XRD, TG-DTA, FTIR and TEM. Effect of Ni(2+) ions doping on the adsorption of chromate on goethite was investigated at pH-3, -5 and -7 in the temperature range 303-323K. It was found that adsorption of chromate increases with decreasing pH and increasing temperature on both pure and Ni(2+)-doped goethite. Adsorption of chromate was found to increase from 61.4% to 82.92% with Ni(2+) ion doping in goethite matrix at the lowest pH (pH-3) and highest temperature (323K), using 1.02 mmol L(-1) chromate solution. Langmuir isotherm was found applicable to the experimental data. The values of Delta H (isosteric heat of adsorption) calculated for both the samples of goethite were positive, showing endothermic nature of the adsorption process.
authors.affiliation: National Center of Excellence for Physical Chemistry, Peshawar University, Peshawar 25120, Pakistan. smustafa49@yahoo.com
authors.forename: Syed
authors.initials: S
authors.lastname: Mustafa
authors.forename: Sadullah
authors.initials: S
authors.lastname: Khan
authors.forename: Muhammad
authors.initials: M
authors.lastname: Iqbal Zaman
mesh_terms: D000327:Adsorption; D002840:Chromates / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007501:Iron / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry*; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D008903:Minerals; D009532:Nickel / Q000737:chemistry*; D055585:Physical Phenomena; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013818:Thermogravimetry
chemical_list: D002840:Chromates; D007477:Ions; D058085:Iron Compounds; D008903:Minerals; C094886:goethite; D009532:Nickel; D007501:Iron