Activated alumina

About: Activated alumina is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 31090 citations.

Performance of a water defluoridation plant in a rural area in South Africa

Abstract: The fluoride concentration of a borehole water supply in a rural area (Madibeng Local Municipality, North West Province, South Africa) varies between 5 and 6 mg/.. This water is therefore not suitable for potable purposes because the high fluoride concentration may cause mottling of tooth enamel in children and fluorosis in adults. Therefore, the fluoride concentration should be reduced to less than 1.5 mg/. to make the water suitable for potable purposes. The activated alumina and reverse osmosis processes are both processes that can be very effectively applied for water defluoridation. The activated alumina process, however, is considered to be a more simple and robust process for water defluoridation, especially in a rural area. Therefore, the activated alumina process was selected for water defluoridation. An activated alumina plant was designed, constructed and commissioned in the rural area. Fluoride in the feed water is removed from 6 to 8 mg/. to less than 1.5 mg/.. No reduction in plant output was experienced over 6 service cycles. Therefore, it appears that fouling of the activated alumina should not be a problem. Plant output varied between 940 and 1 296 m3 to a fluoride breakthrough of approximately 2.0 mg/.. No significant operational problems were experienced during commissioning and the plant is performing satisfactorily. Spent regenerant is disposed of into evaporation ponds. It was demonstrated that a 1st world technology could be effectively applied in a rural area with proper training and supervision of the operators. The capital and operational costs of the 200 m3/d defluoridation plant are estimated at approximately R1.2m. and R0.7/m3 treated water.

Equilibrium and Kinetic Studies of Adsorption of Boron on Activated Alumina

Abstract: Boron is widely distributed in the environment, mainly in the form of boric acid or borate salts, and its contamination of waters is a concern around the world. This study focuses on boron removal by means of adsorption onto activated alumina. Optimum adsorption was achieved in the pH range 8.0 to 8.5. Approximately 60% (by mass) boron removal was achieved using an adsorbent dose of 5 g at an initial boron concentration of 50 mg/L. Adsorption isotherms at 10, 20, and 30 degrees C were investigated. The results fitted with the Langmuir and Freundlich equations showed a monolayer adsorption onto a surface, with a finite number of identical sites. To study the rate-limiting step, the adsorption kinetic data of boron were analyzed using first-order (Lagergren) and second-order kinetic models. The experimental results obtained showed that the adsorption process followed a second-order kinetic model.

Removal of heavy metal ions by filtration on activated alumina-assisted magnetic field

Abstract: Magnetic field (MF), among others, influences more intense decomposition of many compounds, increases adsorption on the surface of the phase separation, as well as accelerates oxidation and reduction reactions. Therefore, they are used in the research as an aid for filtration process, which is one of the most popular stopping and separating processes for different components in different reservoirs. Beds usually function as an adsorbent, thus both filtration and adsorption processes are often. One of the inorganic sorbents that is used to remove metals and anions present in water is Al2O3. As part of this work, we investigated the use of a constant external MF as an elementary additional process to improve the filtration efficiency on activated alumina. The purpose of the study was to compare the effectiveness of the removal of elements (Fe, Mn, Cd, Cr, Cu, Pb, Zn, and Ni) from model aqueous solutions during the process of filtration assisted and not assisted by an MF on activated alumina. In addition, the purpose of the work was also to determine the influence of MF on the removal of these elements, as well as their affinity to physical properties of the adsorbate under the influence of MF. As a result of the experiment, it was proved that the MF support of the filtration on activated alumina for the removal of selected elements is more effective than the filtration without MF. Studies have shown that removal of individual metals occurs according to the following series of affinity toward alumina in magnetized samples: Pb > Mn > Ni > Zn > Cu > Fe > Cd > Cr.