Removal of cadmium from aqueous solution using nano Prosopis cineraria leaf ash (NPCLA)

Background: Heavy metal pollution has become one of the most severe environmental problems, therefore, the present study was conducted to investigate removal of cadmium (Cd) from aqueous solution. Methods: In the present study, nano Prosopis cineraria leaf ash (NPCLA) was used as an adsorbent for removing Cd from aqueous solution. Contact time, initial pH of the solutions, sorbent dosages, and initial Cd (II) concentration were considered as parameters affecting Cd removal efficiency. The experiments were designed by Design of Expert (DOE) software. Results: It was revealed that an NPCLA dosage of 2.45 gL-1, pH of 6.3, and initial Cd (II) concentration of 20.7 mgL-1 in contact time of 60 min was the optimum condition for removal of Cd (II) in the domain of experiments and at this optimum condition, the prediction value of removal efficiency was found 99.9%. Based on the results of kinetics experiments, the sorption system and experiment data of Cd (II) adsorption on the NPCLA followed the pseudo-second-order kinetic model. Freundlich, Langmuir, Brunauer-Emmett-Teller (BET), and Temkin isotherm models were investigated. The equilibrium adsorption data were fitted well with linearly transformed Langmuir isotherm with a correlation coefficient of R2 = 0.9877, and the maximum sorption capacity of NPCLA was obtained to be 25.25 mgg-1. Conclusion: In laboratory conditions, NPCLA can remove Cd from aqueous solution with a high efficiency. Therefore, due to this plant's availability and cheapness, NPCLA can be considered a suitable option for producing adsorbents on industrial scales.