Conventional and microwave hydrothermal synthesis of zeolite ZSM-5 from the cupola slag

ZSM-5 type zeolites have been prepared from cupola slag waste using both conventional hydrothermal and microwave syntheses at 130–200 °C. The ZSM-5 was synthesized by conventional heating by taking advantage of the high silica content of cupola slags. Microwave heating increased the rate of ZSM-5 formation by 4 times at 150 °C compared with conventional heating. The Si/Al ratio of the ZSM-5 produced by the conventional heating and the microwave crystallization were similar 28 and 29, respectively. The conventional-heating produced ZSM-5 particles 3 μm in diameter, while, microwave-heating produced smaller ZSM-5 particles only 0.3 μm in size.     

Conventional hydrothermal synthesis of Na-A zeolite from cupola slag and aluminum sludge

Na-A type zeolites were prepared from two industrial wastes: the solid by-product of cupola slag and aluminum sludge from an aluminum plating plant. Two preparation methods using the same starting material compositions were carried out. In the first method, alkaline fusion was introduced, followed by the hydrothermal treatment to obtain sodium aluminosilicate which was then crystallized in NaOH solution under the condition of 90 ± 3 °C for 1–9 h with different H₂O/SiO₂ ratios. The result shows that higher H₂O/SiO₂ ratio increases the rate of crystallization. The largest amount of crystallinity for Na-A was found at 3 h. In the second method, alkaline hydrothermal treatment without fusion was carried out in the same condition as the first method. No Na-A zeolite was obtained by this method. The changes of the dissolved amounts of Si⁴⁺ and Al³⁺ in 3 M NaOH were investigated during the hydrothermal reaction.     

Experimental optimization of activated carbon synthesis by the simplex search method

To compete with the low price of petrol, thermochemical conversion of biomass should be viewed as both an energy and chemical source. Catalytic pyrolysis can produce activated carbon as a chemical and energy as a by-product, if inexpensive catalysts are available. In this paper, two parameters, namely NaCl (used as catalyst) and temperature, were found to affect the quality of the activated carbon produced from coconut shell and sawdust. Without mathematical modelling of the process, the Simplex search method led to the following maximum iodine numbers: for coconut shell, 685·8 mg/g at 794°C and 3·15 g NaCl/g coconut shell; for sawdust, 581·1 mg/g at 751°C and 5·52 g NaCl/g sawdust.