In search of a recyclable sulphur dioxide sponge-a new look at an old system.

The sulphur dioxide content and thermal stability of the quinol-SO2 clathrate have been studied by thermogravimetric analysis (TG), its derivative (DTG) and differential scanning calorimetry (DSC). These analyses demonstrated the thermal recoverability of the quinol from the clathrate and hence its potential use as a sponge for SO2 present in the environment as a pollutant. Similarly, Bu4N(+)I(-) was found to occlude NO2 and SO2 at 50°C in solution.

Entrapping of organic wastes by coordination clathrates.

The feasibility of the Hofmann clathrates Ni(CN)2(NH3)·G(G=guest molecule) and the octahedral Werner-type complexes Ni(X)2(L)4 (X=NCS, NCO, CH3CO2, C6H5CO2; L=Py, 4-Mepy) as a scavenger for organic substrates in a polluted aqueous or organic medium is dependent on the complex lability, thermal stability and reversibility in solvent trapping which can be conveniently studied by thermogravimetric means. Besides the parent monomeric octahedral complexes, all the thermal decompositional intermediates, namely, monomeric tetrahedral, dimeric octahedral and polymeric octahedral, are also potential scavengers for selected organic substances though they operate via a cycle of bond-making and bond-breaking processes.