Synthesis of geopolymer-supported zeolites via robust one-step method and their adsorption potential

Abstract

The present study proposes a robust one-step hydrothermal treatment method for synthesis of high strength geopolymer-supported zeolites utilizing industrial by-products (fly ash and blast furnace slag), which can be potentially used as bulk-type solid adsorbents. The results revealed that the geopolymer-supported zeolites, possessing distinct strengths, zeolite phases (Na-P1, Na-chabazite, and analcime) and pore features depending on the mix design and synthesis conditions, can be easily synthesized employing the proposed one-step method. The geopolymer-supported zeolites exhibited the characteristics of mesoporous materials which are typically desired for commercial adsorbents. The maximum adsorption capacity for Pb2+ was found to be about 37.9 mg/g which is relatively higher than the other bulk-type adsorbents reported for Pb2+ to date. Since industrial by-products are used for synthesis of these materials, it will help in reducing the environmental hazards associated with the permanent disposal of such by-products, with an added advantage that these bulk-type solid adsorbents can be easily retrieved after use unlike granular adsorbents.