Optimization of water desalination using carbon-based adsorbents

The objective of this work is to study the removal of Ca, Mg, Na and K from water using carbon-based materials obtained from sewage sludges pyrolysis. For this reason, carbon-based materials were prepared at two different pyrolysis temperatures: 450 (SL-450) and 650°C (SL-650). Also, a third material was prepared washing SL-650 with HNO3:H20 1:1 (vol). These carbon-based material were mixed with solutions with different concentrations of NaCl, KCl, CaCl2 and MgCl2. Results showed that percentages of metal removal followed next sequence Mg2+ > Ca2+ > Na+ ∼ K+ and that the percentage of removal increased with the pH of the initial solution. Similar percentages of ions removal were obtained by SL-450 and SL-650 increasing the percentage of metal removal when the SL-650 washed with acid was used. Metals lixiviation from carbon-based materials decreases with the increment of the pyrolysis temperature. Nevertheless, the properties of raw material and consequently, of carbon-based materials can have a great influence in the adsorption properties of the final carbonaceous material, and so, in the removal of metals from water.