Abstract
Synthetic zeolite and mechanically activated natural clinoptilolite were characterized as water softener materials for efficient removal of Ca/Mg total hardness from aqueous solutions and raw groundwater. The studied materials showed very high adsorption capacity and the adsorption capability of the natural zeolite significantly enhanced with boosting the activation time by 2 h (296 mg/g), 4 h (367 mg/g), 6 h (392 mg/g), and 8 h (450 mg/g) in order. The kinetic scientific studies showed that the adsorption equilibrium might be achieved afterward 60 min for activated natural zeolites and after 90 min for synthetic zeolite. The adsorption process using the synthetic type follow pseudo-second-ordering kinetic (R2 = 0.95) while the mechanically activated clinoptilolite follow Elovich kinetic (R2 > 0.85). The adsorption process utilizing synthetic zeolite-A fitted well with the Langmuir model (R2 > 0.99) and occurred in a monolayer form, while the uptake of Ca/Mg total hardness utilizing mechanical activated natural zeolite fitted well with Freundlich model (R2 ≥ 0.95) and occurs in a multilayer form. Thermodynamic studies from 298 K up to 323 K indicate spontaneous endothermic adsorption of Ca/Mg total hardness using all the zeolitic products. The adsorption by synthetic zeolite as well as activated or the activated natural zeolite has been high pH dependent and the performed tests at pH 6 achieved the best values. Lastly, the mechanically activated synthetic zeolite along with natural zeolite display increased efficiency or effectiveness in the elimination of Ca/Mg total hardness and other water pollutants from groundwater.
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