Optimization of Zinc Ions Removal by Modified Phoenix Dactylifera L. Seeds Using Response Surface Methodology

The current study investigates the role of Phoenix Dactylifera L. (date palm) seeds as an effective biosorbent for removing Zn+2, a toxic heavy metal pollutant usually found in the waste streams of industries like fertilizer, mining and galvanizing etc. Date palm seeds were washed, dried, crushed in 170-300 um and modified by acidic treatment (0.1 MHNO3). The effect of most important parameters i.e., pH (3.5-6.1), initial zinc ion concentration (5-100mg/l), biosorbent dosage (0.1-1g) and contact time (0.5-60sec) have been studied via design expert software (version 8.0.6) of response surface methodology. The Box-Bhenken Design (BBD) was used in Response Surface Methodology (RSM) for designing the experiments and a number of 29 experiments were run. The model suggested by the design expert software was quadratic as it had maximum R2- value (0.9235) which indicated that the predicted values of quadratic model were best fitted to the experimental values. The significance of the factors was indicated by Analysis of Variance (ANOVA). The results showed that the metal uptake increased by increasing initial zinc concentration and decreasing in biosorbent dosage and pH while the contact time had negligible effect on the response surface. The parameters were numerically optimized and the optimum input parameters obtained were pH = 3.52, initial zinc ion concentration = 59.11ppm, biosorbent dosage = 0.1g and contact time = 60min with a metal uptake of 26.84mg/g. Therefore, (Phoenix Dactylifera L.) seeds substantially removed zinc ions under optimum conditions.

Ainy Hafeez, Syed Mohsin Ali Kazmi, Muhammad Sulaiman, Chaudhry Haider Ali and Nadeem Feroze