Relationship between morphology analysis and durability of geopolymer paste

Geopolymer may improve corrosion protection by slowing the corrosion of steel in concrete or paste. When the alkalinity of the paste is reduced, the passivating layer is destroyed. If the paste is more pores, it can be easily absorbed by NaCl solution or moisture. The improved properties of the geopolymer paste increase its durability by preventing corrosive elements from harming the steel contained within the geopolymer paste. Two types of paste were used in this research which geopolymer paste and Ordinary Portland Cement (OPC) paste. A Scanning Electron Microscope (SEM) was used to determine the surface morphology of geopolymer paste and OPC paste. Based on the result of this investigation, the morphology characterisation is related to the concrete’s endurance. The formation of an aluminosilicate gel during the geopolymerisation process is critical for stability, increasing the geopolymer matrix’s density. As a result, this can increase the durability of geopolymer paste compared to OPC paste which geopolymer also can improve corrosion protection of steel in paste.

Photocatalytic Degradation of Methylene Blue from Aqueous Medium onto Perlite-Based Geopolymer

In this work, geopolymer synthesized with perlite and an alkaline activator medium was evaluated as a new adsorbent and photocatalyst for degradation of methylene blue (MB) dye from an aqueous medium. The functional group, the structure, and the morphology of the raw and the synthesized materials were characterized using FT-IR, XRD, and SEM analysis. The degradation of MB in the contaminated solution was examined using the spectrophotometric technique. Several analysis methods revealed the formation of the aluminosilicate gel after the geopolymerization reaction. The kinetics data with UV and without UV irradiations were well fitted with the pseudo-second-order equation. The results indicated that the degradation efficiency of cationic dye by perlite-based geopolymer without and with UV was up to 88.94% and 97.87% in 4 hours, respectively. The degradation efficiencies of methylene blue are in the following order: perlite-based geopolymer under UV irradiations is greater than perlite-based geopolymer without UV irradiations that is larger than UV irradiations. The overall experimental results suggested that the new elaborated material with synergetic adsorption and photocatalytic activities has a great potential for the treatment of water contaminated by hazardous substances.

Influence of Crystallization Time for Synthesis of Zeolite A and Zeolite X from Natural Kaolin

Zeolite A and zeolite X was successfully synthesized from natural kaolin from Lampang province using calcination and two-step method of hydrothermal under the optimum conditions. Firstly, metakaolin was achieved by calcining the kaolin at 700 °C for 2 h. Secondly, hydrothermal experiments can be separated into two steps, the high temperature and short time of hydrothermal, metakaolin was mixed with NaOH to form hydrous sodium aluminosilicate, which was dissolved in dilute HCl. After the filtration, adjusted with deionized water to pH = 7 to form an amorphous aluminosilicate gel. Low temperature and longtime of hydrothermal, aluminosilicate gel was mixed with NaOH to form zeolite A and zeolite X. The optimum conditions for synthesis zeolite A is the high temperature and short time of hydrothermal with NaOH 8 M at 200 °C for 3 h and low temperature and longtime of hydrothermal with NaOH 1 M at 90 °C for 72 h. The optimum conditions for synthesis zeolite X is the high temperature and short time of hydrothermal with NaOH 8 M at 200 °C for 3 h and low temperature and longtime hydrothermal was NaOH 1 M at 90 °C for 120 h. The characterization of zeolite A and zeolite X were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (FT-IR). Keywords: Zeolite A, zeolite X, Kaolin, Hydrothermal, Kaolin

Additive-free synthesis of house-of-card faujasite zeolite by utilizing aluminosilicate gel memory

The gel “memory” effect of aluminosilicate sols was used to tune the mesopore size of hierarchical house-of-card faujasite in the absence of additives, following earlier findings by Khaleel et al. demonstrating the use of pre- and post-nucleation trajectories for the synthesis of high FAU content faujasite nanocrystals.