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Ziziphus lotus has been the subject of several researchs because of its nutritional benefits and ecological attributes. The removal of hexavalent chromium Cr(VI) from a solution using powdered Zizphus lotus fruits, for its qualities of being inexpensive as well as environmentally friendly, was investigated. The results obtained showed that at pH = 2, at 30°C, after 600 min of adsorbent/adsorbate contact, with 100 mg/L as initial concentration of Cr(VI) and a biosorbent dosage of 5 g/L, the biosorption of Cr(VI) on Zizphus lotus fruit powder (ZLFP) is at its maximum rate. The sorption process was exothermic (H° = -6.69 kJ/mol), and was characterized by a positive entropy values (S° = 46.76 J/K mol) suggesting a high affinity of the ZLFP for Cr(VI). Given that the Gibbs free energy (G°) is negative and decreases as temperatures increase from 293 to 323 K, the process of biosorption is both feasible and spontaneous. The Temkin model and the Langmuir model both generated excellent fits to the equilibrium data. The maximum monolayer biosorption capacity was 36.11 mg/g. The pseudo second order model was used to fit the kinetic data relating to the adsorption of Cr(VI) on the ZLFP. The FTIR spectral analysis allowed the characterization of the biochemical groups mainly involved in the sorption of Cr(VI) ions on the ZLFP, and which are: N-C, H-O, O-C, H-C, and O=C. The capacity of Ziziphus lotus fruit as an inexpensive, effective, and ecofriendly biosorbent is confirmed through this study. [ABSTRACT FROM AUTHOR]

Ziziphus lotus is a wild plant that has recently become appreciated mainly due to the antioxidant and nutrient-rich properties of its fruits. The powder of the inedible leaves was investigated in this research in batch mode for its capacity to remove cadmium(II) and lead(II) ions as an ecofriendly and cost-effective biosorbent. Leaves powder revealed the highest uptake rate at pH = 8 and pH = 7 for Cd(II) and Pb(II), consecutively. The best metal adsorption rate is obtained with a temperature ranging from 25°C to 30°C, a contact time of 90 min, an initial ionic concentration of 100 mg/L, and a biosorbent dosage ranging from 3.5 to 5 g/L. The experimental kinetic data of the biosorption process for both heavy metal ions were fitted by the pseudo-second-order model. The equilibrium data fitted very well to the Langmuir model and Temkin model. The maximum monolayer biosorption capacities were 70.78 and 80.75 mg/g for Cd(II) and Pb(II), respectively. The main chemical groups which are involved in the trapping of Cd(II) and Pb(II) and which have been revealed by Fourier-transform infrared spectral analysis are: O-C, O=C, H-O, H-C, and N-C. The biosorption was endothermic (ΔH° = 7.33 kJ/mol for Cd(II), and 5.33 kJ/mol for Pb(II)). The reaction was accompanied by a decrease in entropy (ΔS° = -19.87 J/K·mol for Cd(II), and -8.38 J/K·mol for Pb(II)). When the temperature increases from 293 to 333 K, the Gibbs energy (ΔG°) increased, indicating that biosorption was less feasible at higher temperatures. The present research confirms that Z. lotus leaves could be exploited as a low-cost and an effective biosorbent for the elimination of Cd(II) and Pb(II) ions from aqueous solution. [ABSTRACT FROM AUTHOR]

The removal of cadmium (II) and lead (II) ions from aqueous solutions by the Ziziphus lotus fruits powder, as inexpensive and eco-friendly biosorbent, was studied in batch mode. Fruits powder (FP) revealed the highest uptake rate at pH=8 and pH=7 for Cd(II) and Pb(II) consecutively. The best metal adsorption rate is obtained with a temperature ranging from 25 to 30 °C, a contact time of 90 min, an initial ionic concentration of 100 mg/L, and a biosorbent dosage ranging from 3.5 to 5 g/L. The experimental kinetic data of the biosorption process for both heavy metal ions were fitted by the pseudo second order model. The equilibrium data fitted very well to the Langmuir model. The maximum monolayer biosorption capacities were 33.94 mg/g and 69.06 mg/g for Cd(II) and Pb(II) respectively. The main chemical groups which are involved in the trapping of Cd(II) and Pb(II) and which have been revealed by FTIR spectral analysis are: N-C, O=C, H-O, H-C, and O-C. The present research confirms that Z. lotus fruits could be exploited as a low-cost and an effective biosorbent for the elimination of Cd(II) and Pb(II) ions from aqueous solution. [ABSTRACT FROM AUTHOR]