Synthesis and characterization of geopolymer foams from mineral wastes: application as adsorbent for Cu(II) and Pb(II) ions from aqueous solutions

Urban and industrial effluents are responsible for pollutant of which organic, mineral or physical nature. This gives these effluents aggressive and harmful character for the ecosystem and water resources. This work focuses on developing a porous geopolymeric materials as a low-cost, non-toxicity, and easy synthesis adsorbent for removing toxic metals from water. Brick waste and phosphogypsum were used as aluminosilicate raw materials for the synthesis of geopolymers. The silica fume was used as a blowing agent. The prepared geopolymers were characterized by Fourier-transform infrared spectroscopy and X-ray diffraction analysis technics, and were used to investigate the adsorption of Cu(II) and Pb(II) ions in the batch mode. Results show that the studied materials are rich mainly of quartz, cristobalite, and mullite. Adsorption experiments indicate that the equilibrium of Cu(II) and Pb(II) ions uptake can be reached at approximately 120 min (pH 5.0). The maximum removal efficiency of Cu(II) and Pb(II) observed was 55.55 and 83.33 mg center dot g(-1), respectively for geo-M2Na10 (waste brick + phosphogypsum + silica fume + NaOH) sample. The studied geopolymers exhibit a high adsorption capacity for Cu(II) and Pb(II) at initial concentration ranging from 50 to 400 mg center dot L-1. It was also found that the kinetic data are perfectly flow the pseudo-second-order model. The isotherm data of Cu(II) and Pb(II) adsorption onto the prepared adsorbents obeyed to the Langmuir model.