Impact of NHOH treatment on the ion exchange and pore characteristics of a metakaolin-based geopolymer.

We investigated the viability and influence of NHOH post-synthetic treatment on the pore characteristics of geopolymers. Geopolymers are a class of materials with amorphous aluminosilicate three-dimensional frameworks, regarded as amorphous analogues of zeolites. Similar to zeolites, when geopolymers are used in catalysis or adsorption applications, post-synthetic treatments such as ion exchange with NH salts (, NHCl and NHNO) and desilication (using strong bases such as NaOH) are necessary to introduce active sites and modify their pore structure, respectively.

Entrapment of Acridine Orange in Metakaolin-Based Geopolymer: A Feasibility Study.

Few studies have explored the immobilization of organic macromolecules within the geopolymer matrix, and some have found their chemical instability in the highly alkaline geopolymerization media. The present work reports on the feasibility of encapsulating the potentially toxic acridine orange (AO) dye in a metakaolin based geopolymer while maintaining its structural integrity. The proper structural, chemical, and mechanical stabilities of the final products were ascertained using Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric (TGA/DTG), and mechanical analyses, whereas the dye integrity and its stability inside the geopolymer were investigated by the UV-Vis analysis.

Alkali-Activation of Synthetic Aluminosilicate Glass With Basaltic Composition.

Alkali-activated materials (AAMs) are a potential alternative to Portland cement because they can have high strength, good durability and low environmental impact. This paper reports on the structural and mechanical characteristics of aluminosilicate glass with basalt-like compositions, as a feedstock for AAMs. The alkali-activation kinetics, microstructure, and mechanical performance of the alkali activated glass were investigated.

The Effect of Fibrous Reinforcement on the Polycondensation Degree of Slag-Based Alkali Activated Composites.

Alternative cementitious binders, based on industrial side streams, characterized by a low carbon footprint, are profitably proposed to partially replace Portland cement. Among these alternatives, alkali-activated materials have attracted attention as a promising cementitious binder. In this paper, the chemical stability of the matrix, in fiber-reinforced slag-based alkali-activated composites, was studied, in order to assess any possible effect of the presence of the reinforcement on the chemistry of polycondensation.