Performance Comparison of Two Types of Ecofriendly Modified Clinoptilolite for Reducing the Wastewater Salinity

This study concerns the first-time removal of salt ions from industrial wastewater by a new prepared MgO clinoptilolite (MgO-Clino) and the comparison of its adsorption performance with that of Ca-alg/Clino beads (Ca-Alg/Clino beads). The MgO clinoptilolite was obtained by impregnating purified clinoptilolite in MgCl 2 and the latter by crosslinking clinoptilolite with sodium alginate (2%) and calcium chloride CaCl 2 .2H 2 O (4%) solutions. Adsorption experiments were carried out in batch systems to determine the amount of salt ions adsorbed as a function of solution pH, adsorbent dose, initial salt concentration and contact time; The optimal condition was achieved at a pH value of 7.0, an adsorbent amount of 3 g, an initial concentration of 6 g/L, and a contact time of 60 min. Under optimum conditions, 63% and 95% salt ions removal efficiencies were obtained using MgO-Clino and Ca-Alg/Clino beads respectively. The adsorption isotherms data follow well the Langmuir model. The monolayer adsorption capacity (Q max ) of MgO-Clino is 32 mg/g and that of Ca-Alg/Clino beads is 53 mg/g. All kinetic experimental data favor pseudo second-order model. MgO-Clino and Ca-Alg/Clino beads remove efficiently salt ions from the analyzed industrial effluent. The application of this innovative and ecofriendly adsorbent type on a real sample in batch mode has made it possible to reduce the salinity below the Tunisian standard for reuse and discharge into the natural environment. Based on these promising results, the design of a large-scale prototype is in progress to preserve the environment and save the industrialist from paying annual penalties.