Abstract

Egyptian white sand (EWS) was used as an adsorbent for the selective separation of Cr(III) from phosphate solutions which is to be determined colorimetrically using 1,5-diphenylcarbazide. The experimental factors affecting the maximum selective adsorption/desorption of Cr(III) on/from EWS where the amount of adsorbent (g), pH of initial concentration of Cr(III) in solution, contact time, temperature and initial concentration of Cr(III) in solution were investigated. No effect of [PO₄]^3-, Ti(IV) and Fe(III) on Cr(III) sorption were verified. Accuracy and relative standard deviations (RSD) were acceptable for all the analyses. The maximum sorption capacity, Q_e, of adsorbed Cr(III) per gram of sand was 93.5 mg/g, at EWS concentration 20 g/L, pH 0.8, contact time 120 min and temperature 30°C for adsorption of Cr(III) on EWS, and pH 0.4, contact time 6 min and temperature 25°C for desorption of Cr(III) from EWS.

Key words: Ilmenite, phosphoric acid, Chromium(III), Egyptian white sand (EWS), adsorption, desorption.