PREPARATION OF ADSORBENT FROM PHOSPHATE ROCK WASTE TO BE USED FOR THE REMOVAL OF HEAVY METAL IONS FROM WASTEWATER

In this study a cost-effective adsorbent was prepared from phosphate rock waste. An abundant phosphate rock waste was generated, as by-product, from phosphate concentration processes. Phosphate rock waste was activated by chemical activators (including different concentration of HNO3 and NaOH or with both). The developed adsorbent was characterized using different techniques (XRD, XRF and SEM). Batch experiments were conducted to test the heavy metal ions (Cd+2, Cu+2, Ni+2, Pb+2 and Zn+2) removal efficiency by the developed adsorbent. The adsorption process was evaluated as a function of various operating parameters such as contact time, solution pH, temperature, initial metal ion concentration, and adsorbent dosage. The results concluded that activation phosphate rock waste was effective with 2M HNO3, and the developed adsorbent is suitable for effective removal of Cd+2, Cu+2, Ni+2, Pb+2 and Zn+2 from aqueous solution. Initial uptake of these metal ions increases with time and reaches equilibrium at 60 min, while the optimum adsorbent dosage and solution temperature were 0.5 g 100 mL-1 and 25°C, respectively. The adsorption process was pH-dependent with high adsorption capacity at pH 7. The experimental isotherms data were analyzed using the Langmuir, and Freundlich models. The data obtained from adsorption isotherms of metal ions at different time fitted well to linear form of Langmuir model.