Hamzah Fansuri, I’Is M. Anisatun, Anif Fatmawati, Wahyu Prasetyo Utomo, Warih Supriadi, Ridho Bayuaji, Subaer
This study investigates the immobilization of Cd2+ and Cr3+ by using geopolymer based on PT. IPMOMI fly ash. The best composition of geopolymer paste was determined based on the highest magnitude of its 7 days compressive strength. Geopolymer paste were prepared by varying SiO2/Al2O3 and Na2O/SiO2 molar ratio of the starting materials. X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) were employed to examined these compositions. The molar ratio of SiO2/Al2O3 was found to 6.46 produce the highest compressive strength of the resulting geopolymer namely 25 MPa and increased to 33.17 MPa by adjusting the ratio of Na2O/SiO2 to 0.65. Cd2+ and Cr3+ cations were added into geopolymer paste resin at the level of 1000 – 16000 ppm (mg/kg fly ash) and it was found to improve their compressive strength. The addition of 4000 ppm of Cd2+ increased the compressive strength to 38.6 MPa while the inclusion of 6800 ppm of Cr3+ reached 47.83 MPa. Further addition of cations reduced these values and the lowest compressive strength was observed on the addition of 16000 ppm of Cd2+ and Cr3+ namely 8.65 MPa and 4.39 MPa, respectively. Leaching test was conducted by using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and the distribution of heavy metal cations were examined by using SEM-EDX. The results showed that geopolymer paste were able to immobilize Cr3+ at the studied level as there was no trace of Cr3+ detected after 6.5 hours of leaching. Geopolymer was also found to completely immobilize Cd2+ at the level of 1000 ppm albeit the addition of 16000 ppm results in 6.26% leached out of this cation. © 2016 Trans Tech Publications, Switzerland.
Department of Chemistry, Institut Teknologi Sepuluh Nopember, Surabaya, 60111, Indonesia; Department of Civil Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, 60111, Indonesia; Department of Physics, Universitas Negeri Makassar, Makasar, Indonesia; Konsorsium Riset Geopolimer Indonesia (KORIGI), Lab Beton dan Bahan Bangunan ITS, Surabaya, Indonesia
