PREPARATION OF BASIC YTTRIUM CARBONATE FOR PHOSPHATE REMOVAL

Removal of phosphate ions from aqueous solutions has been studied with basic yttrium carbonate (BYC) of different compositions prepared by h omogeneous precipitation with yttrium chloride and urea. Higher carbon ate content was obtained with higher concentration of urea. Removal of phosphate was significant at pH less than 12 and dependent on the com position of BYC. The possible mechanism for removal is ion exchange wi th carbonate or hydroxide groups between pH 7 and 12 and through compl ex formation of phosphate with yttrium ions and ion exchange between p H 2 and 6. The phosphate adsorption capacity of BYC prepared with a hi gher concentration of urea was higher than that of BYC prepared with a lower urea concentration. The removal of phosphate followed a Langmui r model. The BYC of higher carbonate content gave higher percentage re moval in the pH range of 6 to 11. The high phosphate adsorption capaci ty of the compound can be attributed to its carbonate group content an d surface area. The phosphate adsorption was not affected by F-, SO42- , NO3-, Br-, and I- in the basic pH range.