Characterization of Alumina and Removal of Sulphate Ions in Aqueous Stream Using Alumina Prepared by Precipitation Method

Several studies have been done on discovering the potential of alumina as an adsorbent to remove heavy metal such as cadmium and anionic entities such as fluoride and phosphates. The main objective of this research is to produce aluminium oxide (Al2O3) via Precipitation method using only aluminium salt (AlCl3) and ammonium hydroxide (NH4OH) as starting materials. White gel precipitate was formed from this reaction. The precipitate was filtered, calcined, ground and sieved to get alumina particles with desired particles size and adsorbent characteristics. The calcinations temperature was chose to be 750oC and the particles size of the alumina was in a range of 500-1000 micrometer. The alumina produced was characterized to know its organic structure, surface area and surface morphology. The adsorption capacity towards metal ion was determined using DR/4000 Spectrophotometer by applying Method 8051. The synthesized adsorbent has BET surface area of 166 m2/g and average pore diameter of 8.6 nm. Percent metal uptakes of sulphate ion were increased with increasing concentration of initial sulphate concentrations. The adsorption was optimized at the initial concentration of 50 ppm for synthesized alumina and 40 ppm for commercialized alumina. Adsorption of sulphate ion onto surface of alumina has occurred proportionally with increasing contact time while equilibrium point was attained after 45 minutes for synthesized alumina and 55 minutes for commercialized alumina. The data of adsorption studies on synthesized alumina was found to be fitted the Langmuir and Freundlich isotherm with linear regression constant of 0.99 and 0.98 respectively while commercialized alumina can be represented by Langmuir model.Kinetic study shows that the adsorption using synthesized and commercialized alumina follows pseudo second order kinetics with correlation coefficient of 0.96 and 0.98 respectively which relies on the assumption that chemisorptions may be the rate limiting step