Regeneration of spent activated carbon obtained from home filtration system and applying it for heavy metals adsorption

Recently, important progress has been achieved in adsorption of heavy metals from wastewater. However, recycling of the spent adsorbents did not get much attention. Thus, the main goal of this contribution is to address the feasibility of recovering spent activated carbon collected from exhausted home filtration systems. Spent activated carbon was regenerated by acidic-basic treatment. The regenerated activated carbon was tested for adsorption of copper under different conditions including: Temperature, initial concentration, mass of adsorbent, solution pH, and time. Results indicated that Cu2+ uptake dramatically increased by increasing initial concentration, pH (up to 5.5), and decreasing temperature from 333 K to 293 K. Thermodynamic analysis indicated a spontaneous (Delta G < 0) and exothermic (Delta H degrees < 0) process. Both Freundlich and Langmuir isotherms fitted Cu2+ adsorption on regenerated activated carbon indicating that both physical and chemical adsorption contribute in the separation process. Kinetic analysis revealed that pseudo first-order model is better in fitting results than pseudo second-order model with R-2 value of 0.982 compared to 0.974 for the pseudo second-order model. Furthermore, intraparticle model showed that adsorption of copper occurs in three steps including boundary layer diffusion, porous diffusion, and adsorption on the surface. After ten successive adsorption-desorption sequences, the adsorption efficiency was 87% of the first cycle.