Combining different treatment strategies successively or simultaneously has become recommended to achieve high purification standards for the treated discharged water. The current work focused on combining electrocoagulation, ion-exchange, and ultrasonication treatment approaches for the simultaneous removal of copper, nickel, and zinc ions from water. The removal of the three studied ions was significantly enhanced by increasing the power density (4–10 mA/cm2) and NaCl salt concentration (0.5–1.5 g/L) at a natural solution pH. The simultaneous removal of these metal ions at 4 mA/cm2 and 1 g NaCl/L was highly improved by introducing 1 g/L of mordenite zeolite as an ion-exchanger. A remarkable removal of heavy metals was reported, as the initial concentration of each metal decreased from approximately 50 ppm to 1.19 for nickel, 3.06 for zinc, and less than 1 ppm for copper. In contrast, ultrasonication did not show any improvement in the treatment process. The extended Langmuir isotherm model convincingly described the experimental data; the Temkin and Dubinin-Radushkevich isotherm models have proven that the removal processes were physical and exothermic. Finally, the pseudo-second-order kinetics model appropriately explained the kinetics of the process with correlation coefficients of 0.9337 and 0.9016, respectively.
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