This study was focused on Nigella sativa Linn. as an alternative absorbent in order to remove As (III) and arsenate As (V) from synthetic waste water. As such, Nigella sativa L. was collected from Burydah A-Qassim. Batch experiments were conducted to determine the adsorptive efficiency of Nigella sativaL. to remove As (III) and arsenate As (V) from waste water. The preliminary experiments were revealed that alkaline solutions (pH>9) without Nigella sativaL. caused homogeneous oxidation of As (III) to As (V) so the adsorption process was investigated at pH range 2-8. The batch experiments were revealed that adsorption of As ion on Nigella sativaL. was maximal at low pH (at a 3.0) value. The adsorption studies revealed that the ongoing adsorption validates Langmuir adsorption isotherms at temperatures 25, 35 and 45°C. The adsorption isotherm data was also employed to calculate the thermodynamic parameter of Gibb’s free energy which gives a negative value for the adsorption of As ion on Nigella sativaL. The negative values of free energy indicate the feasibility and spontaneous nature of the adsorption process. From these results, it can be concluded that the Nigella sativaL. could be a good adsorbent for the removal of cationic metals coming from waste water.
S.M. El-Said, M.B.S. Alamri, Ali-Bin Saleh El-Barak and O. Alsogair, 2009. Adsorptive Removal of Arsenite as (III) and Arsenate as (V) Heavy Metals from Waste Water using Nigella sativa L.. Asian Journal of Scientific Research, 2: 96-104.