Optimization of Cadmium Removal from Water by Hydroxyapatite Using Experimental Design Methodology

ABSTRACT

The presence of cadmium in water is a serious threat to the environment. The removal of cadmium using hydroxyapatite as an adsorbent was studied in an aqueous system. Hydroxyapatite was prepared to process the adsorption of cadmium from aqueous solution. Experimental design methodology and response surface methodology (RSM) with a quadratic model associated with central composite design was used to optimize the pH, initial heavy metal concentration, final volume, and adsorbent dosage for the removal of cadmium. Analysis of variance identified significant factors on each parameter. RSM indicated that a pH of 8.5, a sample volume of 166 mL, an adsorbent of dosage 0.57 g, and a contact time of 82 min were optimal for the adsorption of Cd(II). Under these conditions, the removal of Cd(II) was 895 mg g^−1.

KEYWORDS:

• Adsorption
• cadmium
• central composite design
• hydroxyapatite
• response surface methodology