Water reuse: Brackish water desalination using Prosopis juliflora

Abstract

Prosopis juliflora is a plant species that have the potential to yield significant environmental and economic benefits. It is used widely as a source of biofuel, food, feed and as an adsorbent in water treatment. In this study, a potential usage of P. juliflora leaves and seeds for removal of sodium ion from synthetic brackish water was investigated. Batch experiments were conducted at different values of pH, initial concentration, and temperature. The results showed that the optimum pH of Na+ removal was pH 2 for the seeds and pH 4 for the leaves. In addition, the high adsorption capacity of 280 mg/g for seeds and 146 mg/g for leaves were obtained at 25 �C and 35 �C, respectively. The Langmuir maximum adsorption capacities were 1000 mg/g for seeds and 222 mg/g for leaves. Negative values of Gibbs free energy, enthalpy, and entropy were obtained for both adsorbents; suggesting that the adsorption process was spontaneous, favored exothermic pathway, and with less randomness between the solid and liquid interface. Fourier transform infrared showed a difference in the shape and intensity of the peaks for both adsorbents before and after the adsorption process; indicating successful interaction of Na+ with NH, OH, CH, and CO groups in P. juliflora seeds and leaves after the adsorption process. This study proved that P. juliflora leaves and seeds could be potentially used as low-cost adsorbents for adsorption of sodium ions from aqueous solution.