Kaolinite bioformation at surface conditions: The role of fungi and bacteria.

Experiments aimed at studying the role of microorganisms in the formation of kaolinite from aluminosilicate solutions (Si:Al = 1:1) are reported. The experiments were carried out at room temperature in presence of living microorganisms, Leonardite humic acid, bacterial debris, bacterial exopolysaccharides (EPS), and some organic ligands. The bacterial debris, EPS, Leonardite and organic ligands were chosen to stabilize Al in octahedral coordination for allowing the crystallization of kaolinite.

Ultrasonic waves induce rapid zeolite synthesis in a seawater solution.

The synthesis of zeolites from fly ash was performed through a low-temperature hydrothermal process with seawater. Compared with the results obtained using the same hydrothermal method but in the absence of sonication, the application of an ultrasonic pre-treatment to the conventional hydrothermal process with seawater reduces the crystallization temperature below that observed when hydrothermal synthesis is performed using distilled water.