JOURNAL OF COLLOID AND INTERFACE SCIENCE ARTICLE

Adsorption of phosphate (PO3 ) from aqueous solution on ac4 tivated red mud (ARM) was studied as a function of time, pH, temperature, concentration of adsorbent and adsorbate in acetic acid–sodium acetate buffer medium. The adsorption of phosphate follows Langmuir as well as Freundlich adsorption isotherms. The process efficiency was found to be 80 –90% at room temperature.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE ARTICLE 204, 169 –172 (1998)JOURNAL OF COLLOID AND INTERFACE SCIENCEARTICLE NO. CS985594 Adsorption of Phosphate from Aqueous Solution Using Activated Red Mud Jyotsnamayee Pradhan, Jasobanta Das, Surendranath Das, and Ravindra Singh Thakur1 Regional Research Laboratory, Council of Scientific & Industrial Research, Bhubaneswar 751 013, India Received January 7, 1998; accepted April 17, 1998 (2), half-burnt dolomite (3), activated carbon (4, 5), coconut Adsorption of phosphate (PO3 ) from aqueous solution on ac- shell carbon (6), clays (7), bentonite (8), ferrihydrite (9), 4tivated red mud (ARM) was studied as a function of time, pH, goethite (10), -alumina (11), and hematite (12). The studiestemperature, concentration of adsorbent and adsorbate in acetic aimed to understand its fixation in soil and to minimizeacid–sodium acetate buffer medium. The adsorption of phosphate eutrophication of lakes, rivers, and ponds (13, 14). Thefollows Langmuir as well as Freundlich adsorption isotherms. The present paper reports preparation of activated red mud andprocess efficiency was found to be 80 –90% at room temperature. use of the same as an adsorbent for phosphate removal fromThis can be extended to the treatment of industrial effluents aqueous solution. Adsorption of phosphate was investigatedcontaining phosphates like that from phosphatic fertilizer as a function of pH, time, temperature, and concentration ofplants. © 1998 Academic Press adsorbate and adsorbent. Key Words: activated red mud; adsorption; phosphate; effluenttreatment. EXPERIMENTAL INTRODUCTION Preparation of Activated Red Mud The problem of solid waste disposal has now attained com- Activated red mud (ARM) was prepared (15) by refluxingplex dimensions. It is essential either to find suitable ways to red mud in 20% HCl for 2 h. After the reflux solution wassafely dispose of these wastes or to suggest novel uses, con- cooled to room temperature, liquor ammonia was added untilsidering them as byproducts. Otherwise, this will remain as an complete precipitation. The precipitate was allowed to settleaccumulated waste contributing highly to environmental pol- and was then filtered and washed thoroughly with distilledlution (1). Utilization techniques for various industrial wastes water until free from ammonia. The residue was dried at 110°Cvary widely depending upon their physico-chemical character- and used for adsorption studies. The specific surface area of the sample was found to be 249 m2/g. All the chemicals used foristics. Red mud is a waste material formed during the produc-tion of alumina when the bauxite ore is subjected to caustic adsorption experiments were of analytical grade.leaching. It is a brick red colored highly alkaline (pH 10 –12)sludge containing mostly oxides of iron, aluminum, titanium, Adsorption Experimentsand silica. The pH of activated red mud, when suspended in distilled Red mud, due to its high aluminum, iron, and calcium water, increases with time even in the absence of an adsor-content, has been suggested as a cheap adsorbent for removal bate metal ion. So the adsorption of phosphate on activatedof toxic metals (e.g., As, Cr, Pb, Cd) as well as for water or red mud was carried out in acetic acid–sodium acetate bufferwastewater treatment ...