Applied Water Science (Jun 2018)
Geochemistry of El-Salam Canal and the adjacent groundwater in north Sinai, Egypt: an application to a water treatment process using magnetic zeolite nanoparticles
Abstract
Abstract Water shortage is among the critical challenges facing many countries located in the arid zone of the southern the Mediterranean region. In the northern Sinai, El-Salam Canal and shallow groundwater in the Quaternary aquifer are considered the main irrigation sources for reclamation of 62,000 acres situated along the Mediterranean coast. The chemistry of surface water of El-Salam Canal varies greatly from the western to the eastern sides. Additionally, the groundwater chemistry is greatly influenced by dilution due to seepage of El-Salam Canal water. The historical and recent records of water chemistry show great variation of the concentrations of dissolved Al3+, Cu2+ and Zn2+ in both surface and groundwater, based on sampling time and locality. The concentrations of these heavy metals occasionally exceed the international recommended limits for drinking and short-term irrigation standards. The removal of dissolved heavy metals from water is crucial to fill the gap between the water supply and the growing demands using possible techniques of water treatment. Consequently, zeolite nanocomposites are one of the materials that have been used for water treatment. Magnetic zeolite nanocomposites (MZNCs) were prepared by the chemical co-precipitation of Fe2+ and Fe3+ in the presence of zeolite. The prepared magnetic nanocomposites were characterized by TEM, SEM, EDX, XRD, FTIR, TGA and VSM. The results show that MZNCs have a cubic crystal structure and good thermal stability. The MZNCs were used to remove Al(III), Zn(II) and Cu(II) from simulated water and then were easily separated from the medium by external permanent magnet. Batch adsorption experiments were conducted, and the effects of pH, initial ion concentration, adsorbent dose and contact time were studied. The selected pH range (pH = 5–6) and temperature (27 °C) in the batch adsorption experiments were close to the pH range of the surface and groundwater field data. Furthermore, the chosen initial concentrations and adsorbent doses were within the heavy metals concentration ranges in El-Salam Canal and the adjacent groundwater. The MZNCs show great removal capacity of heavy metals where 0.1 g is able to clean contaminated water with high concentrations (0.5–3 g/l) of Cu(II) and Zn(II) within 20 min and within 30 min for Al(III). The adsorption kinetics data of the system were well fitted to pseudo-second-order model, which indicates a faster kinetic sorption by the composites. Adsorption isotherms were studied using Langmuir and Freundlich isotherms. Although both of them fit the data, the Freundlich isotherm had the best fit for the selected metals.
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