Porous alkali‐activated material from hypergolic coal gangue by microwave foaming for methylene blue removal
Xinyu Li, Lei Liu, Chengying Bai, Kun Yang, Ting Zheng, Shuang Lü, Hongqiang Li, Yingjie Qiao, Paolo Colombo
Abstract
Abstract Overall, 100% hypergolic coal gangue (HCG)‐based geopolymer foams were produced by a novel saponification‐microwave foaming combined route. Microwave foaming with and without expired vegetable oil was first used to produce CG‐based geopolymer foams. Macropores were mainly generated by microwave foaming, and mesopores were mainly obtained by the addition of expired soybean oil that underwent a saponification reaction. The effects of the oil content on the density, porosity, pore morphology, compression strength, and methylene blue adsorption properties were studied. High total porosity (85.9–89.0 vol%) and acceptable compression strength (0.46–1.1 MPa) HCG‐based geopolymer foams were produced. Foams with 12.59 wt% oil exhibited the best adsorption properties, with an adsorption capacity up to 9.4 mg/g and high removal efficiency of about 95.3%. These solid‐waste‐based porous components are promising monolithic adsorbents for wastewater treatment.