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Otrzymywanie specjalnego szkła wodnego potasowo-sodowego modyfikowanego tlenkiem litu. Cz. 2, Aspekty kinetyczne

Malewski W., Ciesielczyk F., Jesionowski T.

Przemysł Chemiczny

2012

T. 91, nr 5

872-874

Zbadano kinetykę procesu rozpuszczania krzemionki amorficznej (Syloid® 244 WR Grace Davison) w mieszaninie wodnych roztworów krzemianów potasu i sodu z dodatkiem wodorotlenku litu dla temp. 55°C i 65°C. Przedstawiono krzywe kinetyczne α = α(t) i r = r(t) dotyczące omawianego procesu. Określono stopnie przemiany dla procesów realizowanych w obu temperaturach oraz szybkość reakcji. Uzyskane wyniki badań odniesiono do teoretycznego równania kinetycznego O’Connora i Greenberga.

Com. amorphous SiO₂ was dissolved in an aq. soln. of K and Na water glasses (with addn. of LiOH) at 55°C and 65°C to study the dissolution kinetics. The dissolution rate increased with the increasing temp. The results were compared with theor. O’Connor-Greenberg equation.

The kinetics of activation and deactivation in the process of water ozonising used for advanced oxidation of the dust waste from moulding sands

Baliński A.

Archives of Foundry Engineering

2009

Vol. 9, iss. 1

25-28

Adding coal dust and organic carriers of the lustrous carbon to bentonite-bonded moulding sands in amounts justified by the technological regime and the use of cores and protective coatings based on organic compounds create serious threats to the environment. During thermal destruction of the individual components of moulding and core sands, some toxic organic compounds are emitted. They form the majority of the Hazardous Air Pollutants (HAPs), and include mainly compounds like benzene, toluene, xylene, naphtalene, hexane, acetaldehyde, acrolein, aniline, cresol and cumene, their polycyclic derivatives, phenol, formaldehyde, and other similar matters. In thus formed dust waste, the amount of which constitutes about 20% of all the waste from foundries using traditional moulding and core sands, there are still full-value materials which can undergo total recycling, providing the HAPs are partially or totally removed from them. The article discusses some problems of the advanced oxidation of selected toxic chemical compounds present in bentonite-bonded moulding sands due to the effect of high temperature. The results of the investigations of the kinetics of the process of maximum water saturation with ozone (acting as an oxidiser) and of the kinetics of the natural process of ozone decomposition to diatomic oxygen were presented. It has been stated that the maximum time of water saturation with ozone using an OZOMATIC OSC-MODULAR 4HC ozone generator and a 1m3 capacity tank with water is 60 minutes. After 30 minute break in the ozonising process, the ozone concentration in water decreases by 40 to 50%. To obtain maximum ozone concentration in water during the next ozonising cycle, it is necessary to have the ozone-generating device running for the next 30 minutes. The stabilisation of ozone concentration in water takes place only after the third ozonising cycle, when it reaches nearly 80% of the maximum value obtained after the first process cycle.