Green Synthesis of the Metakaolin/slag Based Geopolymer for the Effective Removal of Methylene Blue and Pb (II)

In this paper, metakaolin with varying amounts of slag were used to prepare metakaolin/slag based geopolymer adsorbents for removal of methylene blue (MB) and Lead ions (Pb2+). XRD, SEM, FT-IR and BET methods were used to analyze the phase, structure and morphology of the samples. The effects of slag addition, adsorbent dosage, pH value of Pb2+ solution, initial mass concentration, contact time between sample and solution, experimental temperature on the adsorption properties of the metakaolin/slag based geopolymers were explored. Experiments have shown that the metakaolin/slag based geopolymers are mainly consisted of amorphous phases. The structure of the samples does not change obviously with the increase of the amount of slag addition. The kinetic adsorption process of the metakaolin/slag based geopolymer adsorbents for MB and Pb2+ are fitted to the pseudo-second-order model, and followed by the Langmuir isotherm model. The adsorption process of the geopolymer adsorbents occurs spontaneously with exothermic character. The type of metakaolin/slag based geopolymer has good adsorption capacity for MB and Pb2+, which has potential application in wastewater treatment.