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Zeolite A is a crystalline aluminosilicate which has been used as a builder component in laundry detergents for many years. An LCI for the production of Zeolite A ("cradle-to-factory-gate") was carried out on behalf of the European Zeolite producers. Data from five European production sites were collected to generate an average I.CI for Zeolite A. The plants covered more than 77% of the total European production in 199.3 an therefore represent an avcrage situation. The original LCI tables show detailed figurcs =about raw material, intermediates and auxiliary material consnmption. The overall energy flow for the production of I t of anhydrous Zeolite is 22400 MJ with a minimal spread of • 5% over the individual companies. Furthermore 25 air emission parameters and 35 water emission parameters are listed and categorised with respect m their origins e.g. process dependent, transportation, thermal energy and electricity production. Each company is able to compare their individual data with the average LCI to identify any opportunities to improve production processes. In addition, this LCI of Zeolite A provides the basis for any further LCA studies of a product containing Zeolite A, including comparisons and assessments.

The photoreduction of hydrogen peroxide in water under hydrogen of up to 100 atm pressure has been investigated. The reaction involves a chain mechanism with the quantum efficiency for the disappearance of hydrogen peroxide being strongly dependent upon the concentration of hydrogen peroxide. A maximum quantum efficiency of about 35 mol/einstein occurs at a hydrogen peroxide concentration of about 5 X 10-4 M. At higher hydrogen peroxide concentrations the reaction (HO• + H202 -*• H20 + H02•), which leads to chain termination by subsequent H02* reactions, is competitive with the chain-propagating reaction (HO• + H2 -* H20 + H•) so that the quantum efficiency decreases with increasing [H202], At lower hydrogen peroxide concentrations the chain-propagating step ( -+ H202 -*• H20 + HO•) cannot compete with chain termination by ( • + 02 -*• H02•) so the yield again decreases. Scavenging of hydrogen atoms at lower hydrogen peroxide concentrations is not well understood. The participation of H02• radical is inferred from the observation of a strong pH effect which shows an inflection point at a pH near the pKa of H02• (4.88). A complex mechanism for the reaction is proposed and analyzed by numerical integration of the resulting rate expressions. This part of the work is an example of the usefulness of recently developed numerical integration techniques in the analysis of complex nonlinear reaction mechanisms.

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