Activated alumina

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

Community-Based Defluoridation of Groundwater by Electrocoagulation Followed by Activated Alumina Adsorption

Abstract: Water is essential to human life, yet over billion people across the world have no access to safe drinking water. It is evident in the report of WHO that there is an excess fluoride concentration in groundwater of more than 25 countries including developed and developing countries across the world. Widespread fluorosis cases related to the presence of fluoride in groundwater supplies are major public health problems. Electrocoagulation is an emerging technology for fluoride removal. Activated alumina is a common adsorbent for fluoride removal. In this study, electrocoagulation along with sand filtration was tried as a pretreatment followed by activated alumina adsorption. This technology has been installed in Chhoto Irga village of Purulia district of West Bengal. The results show that electrocoagulation can remove fluoride to a significant extent. Provision of activated alumina bed helps to take care of fluoride removal in case of the electrocoagulation setup malfunctions. Electrocoagulation removes a significant amount of fluoride, and therefore, the challenge to the subsequent alumina bed is reduced helping to prolong the life of alumina bed before exhaustion. In this design, the alumina bed is split into two columns – lead and lag. It helps to utilize more adsorption capacity of alumina and also allows for a time before regeneration of an exhausted alumina column can be actually performed without jeopardizing the safety of the treated water. The aluminum concentration was found to be below permissible limit in the drinking water. The community-based and self-sustained defluoridation unit is functioning till date.

Method for removing arsenate ion

Abstract: PROBLEM TO BE SOLVED: To allow spherical activated alumina having a specified Na2 O content and a specified wear rate to satisfy all of cost, handleability and treating effect as an adsorbent by bringing an adsorbent made of the alumina into contact with water contg. arsenate ions and removing the arsenate ions from the water. SOLUTION: Aluminum hydroxide such as gibbsite is calcined for 0.1sec to several min in a flow of hot air at 500-1,200 deg.C, the calcined body is separated and cooled and the resultant activated alumina powder having rehydratability is pulverized and compacted in a sphere shape to obtain spherical activated alumina having <=0.3wt.% Na2 O content and <=1% wear rate. An adsorbent made of the alumina is brought into contact with water contg. arsenate ions and the arsenate ions are removed from the water. The alumina can satisfy all of cost, handleability and treating effect as an adsorbent.

Improved mesoporous catalysts

Abstract: A method of preparing activated alumina catalysts, which have large pore size and greater resistance to the effects of high temperature. The method includes the steps of; forming an aqueous aluminium hydroxide precipitate from mixing an acidic solution and a basic solution; mixing it with a low molecular weight, water dispersable surfactant; forming a homogeneous composite of aluminium hydroxide and surfactant through keeping the aluminium hydroxide and surfactant in a closed environment at approximately 100 °C; and calcining the aluminium hydroxide alumina precipitate and surfactant mixture at greater than 100 °C to eliminate the surfactant and form the activated alumina (AI2O3).An alumina catalyst having a mesoporous structure, formed from nanometer particles of alumina arranged so as to create interstices.

Effects of pH, Surface Area, and Background Matrices on the Removal of Lead from Aqueous Solutions Using Activated Alumina

Abstract: : The metallic compound lead poses a human health risk and is environmentally toxic. The removal of lead from drinking and waste waters is therefore of great importance. To ensure that the lead concentration is reduced to safe levels, conventional treatment procedures for the removal of lead such as chemical precipitation and ion exchange have been used. These methods often do not yield sufficient removal of lead and can be expensive due to the high costs of required chemicals. Aluminum oxide, Al2O3, has been shown to sorb lead from aqueous solutions by concentrating lead at the particle surfaces. Sorption of lead using aluminum oxide (alumina) is effected by many factors, including pH, available surface area, and background compounds or matrices. Each of these variables significantly impacts both the rate of sorption and the equilibrium amount of lead sorbed on the alumina surface. In this investigation, factors effecting the sorption of lead using alumina were quantified. These factors included the influence of solution pH, alumina surface area (particle size), and presence of background matrices. The specific variables examined were pH solutions that ranged from very acidic ( 8.0), alumina particle sizes of >16 (1190 microns) and <200 (74 microns) mesh sizes, and background matrices containing 1.0 mM acetic acid and 0.1 mM sodium chloride. Equilibrium isotherm studies were conducted over the range of variables using known concentrations of alumina and lead in aqueous solutions. The results of this investigation conclude that solution pH plays the most significant role in lead sorption, but alumina particle size and background matrices also decrease the quantity and rate of lead sorption using activated alumina.